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UMI
THE EFFECTS OF SHORT-TERM LOCALIZED CELANGES ON THE DECLINE OF TUBERCULOSIS MORTALITY IN GIBRALTAR, 1860-1967
by
Henry H.C. Choong
.A Thrsis subrnitred in conforrnity with the requirements for the Degree of Doctor of Philosophy Ciraduate Depanment of Anthropoloizy Cniversirv of Toronto
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The Effects of Short-Terni Localizeû Changes On the Decline of Tuberculosis .Mortality in Gibraltar. 1860-196'1. Ph.D.. 1999. Henry H.C.Choong Depanment of Anthropology. University of Toronto.
ABSTRACT
This thesis examines the decline of tuberculosis monality in Gibraltar from 1860 to 1967, and the historical processes that influenced the decline. using time-series analysis and i i fe-table methods. The time-series analysis showed that the decline of tuberculosis monalit v in Gibraltar occurred due to localised. short-tenn changes. Box-Jenkins
( XRIMA) analysis shows that the decline of tuberculosis monality in Gibraltar from 1860 to 1967 was predicated on shon-term local conditions operatine to influence yearly monality rates. and that rhe decline was not due to the natural cvcle of !he disease. Cross- correlation tùncrions indicate that the decline of tuberculosis monality in Gibraltar was slosely related to the overall monality decline before 1900. but deviated after 1900. The high correlation between overall monalitv and tuberculosis monality before 1900 is due ro the predominance of water-borne disease during that penod. whic h reduced resiaance ro tuberculosis Life-table techniques showed that the impact of tuberculosis on life cxpectancy changed correspondingly before and after 1900. Explanations for the decline of tuberculosis rnonalit y O T Gibraltar were souoht in its epidemiological, sanitary, housing and socio-medical hisron. Examination of the historical circumstances of the decline of tuberculosis mortality in Gibraltar showed that before 1900. the decline of ruberculosis monality could be attributed to successive improvements in sanitation and water supply. although there were no direct effons at reducing tuberculosis monality.
.\fier 1900. the predominanr factor influencing the decline in tuberculosis monaiity was a reduction of crowding
.. . III ACKNOWLEDGEMENTS
1 would like to thank Dr. L.A. Sawchuk my thesis supervisor. for his invaluable advice and suppon in this research, both in the field and throu_phout the preparation of the thesis. I would also like to thank my thesis cornmittee: Dn.D.R. Besn. M. Latta F.J.
Melbve. Depanment of Anthropology. University of Toronto. and Dr. D.A. Hemng,
Depanment of Anthropology. McMaster University. My thanks also to the people of
Gibraltar. including Dr C. Finlayson. Gibraltar Museum. and Mr. T.J. Finlayson,
Gibraltar Government .Archivist. For technical assistance, 1 would like to thank K.
Sevmour. M. Erskine. and J Johnson.
For inspiration and advice in research. 1 would like to thank Dr. P.H.von Bitter.
Department of Palaeobiology. Roval Ontario Museum.
To the Company Drs R. Lew and C. Millward. P.T. Berkobin. A.S. Catey.
Mv deepest gratitude goes to my familv for their love and support. and to Nghiêm
Xi Trans. for being there. and for showing me life in between. TABLE OF CONTENTS
CHAPTER 1: ISTRODUCTION
1. I hature and Scope of the Problem 1.2 Aetiolog of Tuberculosis I 3 lnterpretation of Tuberculosis Monaiity Trends 1 4 The Debate on the Cause of the Decline of Tuberci sis 1 5 The Decline of Tuberculosis in Gibraltar in the Context of the Debate 12 1 b The Specific Goals ofthis Study 1 7 Theorerical and Conceptual Framework
CHAF'TER 2: GIBRALTAR: SETTING AND THE POPULATION
2 1 Geographv and Geology 2 3 Climate Z Z The -I'o\t n
2 J The Population of Gibraltar. 1704- 1967 1 900s I soos i 9QU5
CHAPTER 3: JIATERLALS
3 I Sources aiid I'vper of Data Csed -3 2 The Census 3 2 1 Consistent?. of Census Data 3 3 Civil Re~istrationof Deaths 3 4 Esrimating the Zumbers of Deaths from Tuberculosis from the Registers Some Considerations 3 4 1 Tuberculosis in Historical Records 3 4 2 Incompieteness of Xotification CHAPTER 4: ANALYTICAL METHODS
4.1 Choosing the Penod of Study 4.2 Calculation of Generai Mortality Rates and Tuberculosis Mondit): Rates 4.3 Time-Series Analvsis- Studying the Yearly Generai MonaIitv and Tuberculosis Monality Rates 4.3I The Concept of a Deteministic Trend 4 3.2 Box-Jenkins Method Parameters in the Model Model Selection: Autocorrelation and Partial .Irutocorrelations Esrimation of Parameters and Fitting the Model 4 5 3 Measuring the Impact of Histoncal Events on Monality 4 4 Life-Table .Analvsis- Measuring Tuberculosis Monality Differentials by Age and Sex 4 4 I Are-Speciiïc and A-e-and-Cause Specific Monalitv Rates 4 4 2 Ordina? Life-Table and Probabilitv of Dving -i 4 3 Cause-Drlered Life-Table .\nalysis
CHAPTER 5: RESI'LTS
5 I Graphical and 'rime-Series Analysis i 1 I General Jlortality in Gibraltar- Trend and Overall Pattern i I 2 Tuberculosis Mortality in Gibraltar: Trend and Overall Pattern 5 I 3 Pulmonan. and Non-Pulmonary Tuberculosis Monality Patterns 5 1 4 Cornparison Between Tuberculosis. Overall Mortalitv Rates and Other Respiratory D iseases 5.1 5 Difference Between LMale and Fernale Overall Tuberculosis Monalit!. Rates 5 2 Bos-Jenkins .Analysis 5.2.1 Modeling the General Monality Pattern 5.7.2Modeling the Overall Tuberculosis Monality Pattern 5.2.3Modeling the Pulmonaq Tuberculosis Monality Pattern 5.3 internipted ARIMA 5 4 The Analvsis of Age-.And-Sex Specific Monality Rates Using Life-Table Techniques 5 4 1 Life-Expectancy and Monality Differentials by Age and Sex 5 4 2 Age-Specific Probabilities of Dying fiom Ai! Causes 5 4.3 Male Age-Specific Probabilities of Dying From Tuberculosis Pre- i 900 5 4 4 Male Age-Specific Probabilities of Dying From Tuberculosis. Pest- 1900 5 4 5 Female Age-Specific Probabilities of Dying from Tuberculosis~ Pre- 1900 5 5 5 Fernale Age-Specific Probabilities of Dying from Tuberculosis. POSI- 1900 5 6 Impact of Tuberculosis on Life Expectancy: Cause Deleted Life- Table Analvsis 5 6 1 Cornparison Between male and Female Differentials
CHAPTER 6: THE DECLINE OF TUBERCULOSIS MORT.4L1TI' IN GIBRALTAR: AN INTERPRETATION
O 1 Pre- 1900 The Period of High Background Monality in Gibraltar 6 1 2 Housing. Crowding. and the Spread of Disease 6 1 3 Development of Gibraltar's Health and Sanitary Lnfiastructure 6 1 4 Inadequate Water Supply and the Sewage S~stem 6 1 5 Type and Quality of Food during the Period of High Background Monality 6 16 Tuberculosis in the Period of Hiah Background Mortditv
vii 6.1.7 Factors Influencing the Decline of Tuberculosis during the Period of High Background Mondity 6 2 Poa-1900. The Movement to Low Background Monality 6.7.1 Overcrowding and Living Conditions 6.2.2 Type and Qualitv of Food during the Period of Low Background Monality 6.2.3 Tuberculosis in Gibraltar afier 1900 6.2.4Factors Influencing the Decline of Tuberculosis during the Period of Low Background Mondity 6 2 5 Tuberculosis Notification & Detection 6 2.6 Post-Notification: Medical Oficers and Furtiier Measures against Tuberculosis 6 2 7 TB Schemes. Sanatoria and Isolation of Infected Persons 6 1 8 The Tuberculosis Scheme and the Sanitary Cornmissioners' Home O 2 9 Effectiveness of the Tuberculosis Scheme 6 2 10 Education lncreasing Awareness of Preventive Measures b 2 1 1 The Continumg Problems of Overcrowding 6 1 t 2 Housing Reforms and the Decline of Tuberculosis in the 1900s 6 2 13 Evaluatino the Impact of Post- 1900 Changes on Tuberculosis blonality Decline in Gibraltar 6 2 1-1 The Final Stage of the Decline in the Study Period: Poa-World War II Xleasures against Tuberculosis
CHAPTER 7 COSCLCTSIONS
REFERENCES LIST OF TABLES
Table 1 Cause Deleted Li fe-Table Anal ysis. Tuberculosis Removed. Gibraltar
Table 3 Cornparison of the Tuberculosis Monalitv Rates fkom Gibraltar and Selected Countries and Cities. 1881-85
Table 3 Cornparison of the Tuberculosis Monaiity Rates fiom Gibraltar and Selected Countries and Ciries, 190 1 -03
Tabk 4 Mean 3umber of Persons in Different Types of Apartments. Based on Censuses 137
Table 5 Percentage of Familv Occupancy by Nurnber of Rooms. Based On Ccnsuses 142
Table 6 Cornparison of relative Years of Life Gained from Removal of Respiraton Disease to Tuberculosis. Pre-and-Post 1900 144 LIST OF FIGURES
Frontispiece Educational Poster aoainst the Dangers of Consumption In Nineteenth Century Gibraltar
Fiyre 1 Graph of the decline of phthisis mortality in England and Wales 1838-94
Fisure 2 Map of Spain. Morocco, and Gibraltar
Figure 3a Male population of Gibraltar in 1868, 1878, and 1891. 5-year cohons 3 1
Fisure 3b Female population of Gibraltar in 1868, 1878. and 189 1, 5-year cohorts 32
Fisure Ja Illustration of abrupt. permanent impact pattern 48
Fisure -Ib Illustraiion of abmpt. ternporav impact pattern 38
Fisure Jc 1llustration of graduai. permanent impact pattern 48
Figure 5 Outline of the time-series analvsis 50
Figure 6 General rnonality rates. Gibraltar 1860- 1967 57
Fisure 6a Exponent iallv smoothed general mortality rates. Gibraltar 1 860- 1 967 57
Figure 7a Overall tuberculosis monality rates, Gibraltar 1860- 1967 60
Fi-re 7b Euponentiallv smoothed overall tuberculosis monality rates, Gibraltar 1860- 1967 60 Figure 8 Overall pulmonary and non-pulmonary tuberculosis mortalixy rates, Gibraltar 1 860- 1 967 63
Figue 9 Cornparison of tuberculosis and general rnonality rates 63
Figure 1Oa Cross-correlation tùnction of residuals, overall tuberculosis monaiity rates and seneral monaiity rates. Gibraltar 1 860- 1967 65
Figure lob Cross-correlation iünction of residuals, overall tuberculosis rnortality rates and general mortality rates, Gibraltar pre- 1900 66
Figure 1 Oc Cross-correlation function of residuals, overall tuberculosis monalit y rates and general monality rates, Gibraltar
POS- 1900
Figure 1 1 a Comparison of tuberculosis and respiratory disease. Gibraltar 1 860- 1967
Figure I 1 b Bronchitis and pneumonia mortality patterns. Gibraltar 1 860- 1 939
Figure I? Male and female tuberculosis monality rates. Gibraltar 1860-1967
Figure 13a Sex difference in tuberculosis monality rates, Gibraltar 1860- 1967
Figure 1 3b Sex difference in pulmonary tuberculosis monality rates. Gibraltar 1 860- 1967 71 Figure 13c Sex difference in non-pulmonary tuberculosis mortality rates. Gibraltar 1860- 1967
Figure 14a Autocorrelation fùnction of general mortality rates
Figure 14b Partial autocorrelation function of general monality rates
Figure 14c Autocorrelation function of differenced general mort dity rates
Figure 14d Panial autocorrelation function of differenced general monality rates
Fisure 14e .4utocorrelation function of log-transformed and differenced general monaliry rates
Fige 14f Panial autocorrelation fûnction of log-transfonned and differenced general monalitv rates
Fisure 1 5a utoc oc or relation tùnction of ARtMA (O. 1.1 ) residuals of -nenerai monality rates Figure 15b Panial autocorrelation fiinction of ARMA (O, 1.1) residuals ofgeneral monality rates
Figure 1 5c Histogram of the .WMA(0.1.1 I residuals of general mortality rates
Fisure 1 5d Normal probabiiity plot of the ARMA (O. 1.1) residuals of general monality rates
Figure 16a .Autocorrelation function of tuberculosis monalitv rates
xii Figure 16b Panial autocorrelation function of tuberculosis monality rates 80
Figure 16c Autocorrelation Function of differenced tuberculosis monalitv rates 8 1
Figure 16d Panial autocorrelation function of differenced tuberculosis morrality rates. 8 1
Figure 1 7a Autocorrelation function of ARIMA ( 1.1 .O) residuals of tuberculosis mortalitv rates 82
Figur- 1 7b Panial autocorrelation function of ARMA ( 1.1 .O) residuals of tuberculosis rnonality rates 82
Fisure I7c Hiaogam of ARMA ( 1.1 .O) residuals of tuberculosis mortal ity rates 83
Figure 1 7d Xomai probabi lit? plot of the ARIMA ( 1.1 .O) residuals of tuberculosis monality rates 83
Figure 18a PuIrnona? tuberculosis monality rates in males. Gibralrar 1560- 1967
Fisure 1 Sb Pulmonan tuberculosis monalitv rates in males. with outliers removed 88
Figure 19 Pulrnonary tuberculosis mortalitv rates in fernales. Gibraltar i 860- 1967
Figure ZOa Probability of dvins kmal1 causes, males Figure 20b Probability of dying fiom al1 causes. females 98
Figure 2 1a Male probabilities of dying fiom tuberculosis 1 O0
Figure 2 1 b Female probabilities of dying from tuberculosis t O0
xiv LIST OF APPENDICES
Figure la Autocorrelation fùnction of male tuberculosis Mortality rates
Figure Ib Partial autocorrelation hnction of male tuberculosis monality rates
Figure 1c Autocorrelation fiinction of differenced male tuberculosis monality rates
Figure Id Partial autocorreiation fùnction of differenced male tuberculosis monality rates 154
Fisure le Autocorrelation function of log-transformed and differenced male tuberculosis monality rates 155
Fisure If Panial autocorrelation function of log-transformed and differenced rnale tuberculosis monality rates
Fisure 2a Autocomelation Function of ARIMA (O. 1' 1) residuals of male tubercuiosis monality rates
Figure Zb Pmial auiocorrelation function of ARMA (O, 1.1) residuals of male tuberculosis monality rates 156
Figure Ic Histoeram- of ARMA (O. 1.1 ) residuais of male tuberculosis monality rates
Figure 2d Normal probability plot of ARMA (O, 1.1) residuals of rnale tuberculosis monality rates Figure 3a Autocorrelation fùnction of differenced female tuberculosis mortality rates
Figure 3 b Partial autocorrelation fiinction of differenced female tuberculosis mortality rates 158
Figure 4a Autocorrelation function of ARIMA (0,1,1) residuals of female tuberculosis mortality rates 159
Figure 4b Pmial autocorrelat ion function of ARMA (0,1,1) residuals of fernale tuberculosis monality rates 159
Figure 4c Histogram of ARMA (O. 1,l) residuals of female tuberculosis monaiity rates
Figure 4d Normal probabilitv plot of ARMA (O. 1.1) residuals of female tuberculosis monaiity rates 160
Fiyre ja Autocorrelation fbnction of differenced male pulmonap tubercuiosis monalitv rates
Figure 5 b Partial autocorrelation function of differenced male pulmonary t uberculosis mortality rates 16 1
Figure 6a Autocorrelation hnction of AMMA (O, 1.1 ) residuals of differenced male pulmonary tuberculosis mortality rates 162
Figure 6b Partial autocorrelation function of ARIMA (O, 1.1 ) residuals of differenced male pulmonq tubercuiosis monaiity rates 162 Figure 6c Histogram of ARIMA (O, 1,l) residuals of male pulmonary tu berculosis monality rates 163
Figure 6d Normal probability plot of ARIMA (O, 1.1 ) residuals of male pulmonary tuberculosis mortality rates 163
Figure 7a Autocorrelation function of differenced female pulrnonary tuberculosis monality rates
Figure 7b Partial autoconelation function of differenced female pulmonary tuberculosis monality rates
Figure 8a Autocorrelation function of ARIMA (O, 1,1) residuals of female pulmonary tuberculosis mortality rates 165
Figure 8b Panial autocorrelation function of ARIMA (0.1.1) residuals of female pulmonaq tuberculosis monality rates 165
Figure 8c Histooram of ARiMA (O. 1.1 ) residuals of female pulmonary tuberculosis monality rates 166
Figure 8d Normal probabilitv plot of ARIMA (0.1.1) residuals of fernale pulmonary tuberculosis monality rates 166
xvii CHAPTER 1
1.1 Nature and Scope of the Problem
The objective of this research is to explore the decline of tuberculosis mortality in
Gibraltar tiom 1 860 to 1967. and to consider the specifc histoncal processes that precipitated the deciine. Dunng the nineteenrh century. tuberculosis was the scourge of al! levels of society in Europe. striking its victims in their prime of life. A greater killer than intestinal diseases. "consumption" or "phthisis." as tuberculosis was known dunng the Victorian period. accounted for one-third of al1 deaths at that time hmeither respiratory or intestinal diseases ( Wohl 1 983.13 1 ) In nineteenth-century Gibraltar. tuberculosis accounted for as much as 20 percent of al1 deaths The Gibraltar Chronicle (Baker. 18 19) listed as the
Colonv's leading cause of deaths as "Consumption" responsible for 20 out of the 5 1 deaths rhat year .A centun. later. the Annual Report of Health in 19 17 referred to tuberculosis as
--thegeat blot on the Sanitap Hisroc of Gibraltar.. . " (Dansey-Browning 19 1 7)
As in other European counrries. tuberculosis in Gibraltar declined dunng the nineteenth centun- However. tuberculosis continued to be an important cause of mortality as Gibraltar entered the tuentieth century even as it continued to decline Bv the 1930s, the downward tendent?. of tuberculosis monaiity rates encouraged a sense of complacency in the medical comrnuni ty (Long 1 9-10.Comstock 1 9862) Lt was anticipated that tuberculosis
~rouldeventually disappear of its own accord (Cockbum 1963224). Advances in the field of chemotherapy and the discovery of areptomycin after World War lï seemed to provide the means to achieve rhis realitv Kockbum 1963224). Sadly, this optimîsn was unfounded. A steady decline of tuberculosis was documented in most developed nations throughout the
twentieth centu?. but the trend is reversing since the mid-1980s. and cases of tuberculosis
have increased since ( Bames 1995: 1 ). The questions conceming the factors that affect
infection and tuberculosis monality rates. therefore. are still relevant.
Tuberculosis is a "social" disease. demanding that the "impact of social and economic
factors on the individual bt: considered as much as the mechanisms by which the tubercle
bacilli cause damage to the human body" (Dubos and Dubos 1987: xxxvii). "Like infant
rnonaiity tuberculosis is both a proxy for conditions of life and a substantive factor in
i\eavin*~the fabnc of Me" t Rosenberg 1993 1. The factors thar promote the spread of
tuberculosis are found in the elernents of everyday life. including personal and domestic hyene. diet. overcro\~ding.and occupational exposure to infection ( Hardv 1 993.213).
Thus. a high incidence of tuberculosis could be taken as an indicator of highly unfavourable
.jeemingly iiituitivr connecnon betucen such factors and tuberculosis. ~hecorrelation between these factors and resuitmg monalir! rates is not always straightfonvard Famer (1997) demonstrated that large-sîrilct forces such as poveny and economic inequality can strongly intluence the bioloycal nutcorne (persisrence and resurgence in the poor of many indusirialised nations) .Analysis of tuberculosis monalitv at the local Ievel is still needed. as the interaction betwen the cornples aetiolosy of the disease and social and economic factors \\hich produce tne obsenrd rnortality patterns remains unciear (Bryder 1988:l 17). "Problems caused by the ~anabilityand aetiolo- of tuberculosis are less easy to demonarate in a specitic local conrest. ytma! have S~~OUSimplications of the local tuberculosis ecologi' (Hardy 1993) Disease mua be considered more than a purely biologicsl event of one dimension: its context is much more complicated. ".. .incorporating biolooical. cultural. and ofien economic elements in particular. time-specific configurations*' (Rosenberg 1993). In historical demographv. the problem is complicated by the fact that one is ofien limited to the study of monalitv. which although significant. reveals only part aory of involving a complex interaction berween infection. morbidity. and death. The link benueen tuberculosis morbidity and monality is far from clear (Smith 1988:237) Funher undemanding of the decline in monality patterns are needed. Madrigal ( 1992:21 1) underscores the need for . anthropolooical communitv-specific study of monality patterns to cornplexnent large dem~graphicresearch projects" 1.2 Aetiology of Tuberculosis Tuberculosis can affect anv organ of the bodv. but the most fiequent and serious manifestation is infection of the iunss. Tuberculosis is spread through airbome droplets to susceptible individuals by sputum throu_eh coughine or spitting by infected individuals. The disease can be acute and -alloping. chronic or intermittent. Infection can las a lifetime, and those who do not die from the disease carry ir with them and infect other individuals. panicularly those in constant and immediate proxirnity The general path of infection stans early in iife. leading to an ohen umoticed "primary infection" (Lancaster 1 990:82). This may be iollowed by a long. latenr period before infection is apparent. until defences are weakened and the disease becomes active It is convenient to classi& the disease into two fom. pdmonary and non-puimonary ( MacNaltu 1933:13 ) Pulmonary tubercutosis was the greatest killer. responsible for approximately 80-85 per cent of deaths from tuberculosis in the twentieth century (Bryder 1 9883). The non-pulmonw type of the disease may be manifested as many foms: acute miliary tuberculosis. where infection becomes widely disserninated throughout the body. or otien as second- infections like scrofula lupus, tuberculosis of the bones and joints. or tubercular meningitis (Lancaster 199032). The terni "scrofula" refers ro inflammation and degeneration of the Iymph nodes at the sides of the neck and ulceration of the skin surface. ïobes mesemema (wasting) is wastiq and degeneration of the abdominal lymph nodes. panicularlv in infants and in children under five. Lupus vtdguris (infection of the skm) describes brownish nodules in the inner layer of the skin with surface ulceration. especially in the face. Tubercular meningitis (brain fever) sornetimes develops directly. or as a complication of other fornis of tuberculosis. Tuberculosis is dificult to diasnose without radiological and laboratory procedures. Cntii the development of tuberculin skin tests in the early twentieth century ("von Pirquet" 1 907. and %lantous" 1908 1. and mass-radiogaphy in the 1940s. diagnosis was solely based on physical symptoms Diagnosis was not an easy task. because individual svmptoms of tuberculosis are non-specitic lt is dificuit to distinguish between coughs. sputum. and breath-sounds produced by different pulmona~diseases (Rosenkrantz 1987: xix). Until the 1 880s. manifestations of infection by what is now known to be M~cohacrerrtîmrzrbercuiosis \r-ere considered bu laymen and medical pracritioners as separate but related conditions, with distincr aetiolosies ( Smith 1988 3 ) lt seemed to be more of a generaiised condition. rather than a specific disease allowing for accurate diagnosis (Smith 19883) It was not until 1882 that Robert Koch discovered the tubercle bacillus. and demonstrated that tuberculosis in ail organs was the cause of a single disease (Daniel 1997181). The tubercle bacillus was discovered to have tive sources of orign- human bovine. avian murine. and piscine (Bryder 1988:3). Ody the human and bovine sources have been found to cause disease in humans. The bovine form of tuberculosis is most commonly spread by consuming infected milk although infection mav also occur fiom consumption of infected meat. Generai spptoms of tuberculosis are varied. especidy in the early cases. and some cases are asymptomatic. Smith ( 1988:2) lias some generai symptoms: lassitude, imgular appetite, flatulence and loss of weight, irritability, raised and unstable pulse rates, night sweats. facial pallor contrasted with flushed cheeks and wan eyes. emaciation, female arnenhorrhoea and male impotence. running nose, and muent colds. harsh coughuig and frequent spitting of fou1 mucoid sputum. cougbg up blood (haemoptysis), hoarseness or loss of controi of the pitch of the voice. hissing or wheezing in the chest. and fever. Al1 these synptoms could appear sin& or more comrnonly in unpredictable combinations and irregular sequences (Smith l988:Z). 1.3 Interpretation of Tuberculosis Mortality Trends .An implicir assumprion in man? snidies of tubercuiosis monality is that the downward trend found in most European countries was a stable phenomenon. established in previous centuries (Puranen 199 1 100 ). This is because the only statistics on tuberculosis death that are normally available relate to when the death rate frorn tuberculosis was aiready falling. This downward trend has been interpreted as representing in large part the natural cycle of the disease. operarino independentlv of any hurnan efforts (Cornstock 1986:2). Some worken regard tuberculosis as a lon-sranding epidemic where natural selection weeds out those less fit to withstand the effects of tuberculosis infection (Lancaster l990:89). it may be possible \rave advances. the numbcr of bacilliferous individuals will decrease. Up to a point. sontinuous urbanisation will compensate for fewer sources of infection by an increase in the number of contacts. bur rventually open cases would become sufficientlv rare as to make actual isolation possible By ihen. the generai immunity of the population should be so high that increased contact ma! have iittle or no consequence. The social aspect of the disease \wuid then cease to haïe an!. etfect on tuberculosis mortality deciine. SlcKeown ( 1976) postulated a single continuous and unintemipted deciine. Ferebee ( 1967) developed an epidemiological mode1 based on estirnates of new infections, whiiiQ predicts a downward trend. These models are significant in the study of tuberculosis monalitv pattems because of the a prrori assumption of an inevitable downward trend. Cornstock ( 1986) noted that this downward trend was dependent on maintainine both control efforts and the environment ofthe pas. Dubos and Dubos (1987) also rem-hsed tubernilosis rnonalitv patterns showed an apparently spontaneous ebb and flow. However. unlike Grigg, t hey contend that social environmental factors (such as urbanisation). directly or over genetic channels. may have had a significant role in shaping the tuberculosis phenomenon over the paa 150 years. Furthemore. the monality rates have Men so rapidly that explanarions must be sousht in the immediate social and environmental factors. However. the author has not found an- analvsis of the aaual mechanistic behavior of a series of tuberculosk rnonality rates through time A better understanding of the process of the decline in tuberculosis monality rates irself is needed. in addition to a consideration of the factors drivin- thar process. 1.4 The Debate on the Causes of the Decline of Tuberculosis The causes of the drcline of tuberculosis monality remain a subjecr of much discussion Most of the esplanations for the decline of tuberculosis are sought within the social and environmental spheres of housing. nutrition. and sanitation. Even so. scholars have disagreed on the rolcs t hat factors such as housinç and nutrition have played in determining the decline of tuberculosis rnonalitv "The continuing challenge of histoncal tuberculosis research is to achie\.e a riner evaluation of the balance of factors driving the decline of the disease" (Hardy 1993 2 13 Mile it has been shown that the decline of tuberculosis mortality during the late nineteenth and early twentieth centuries was parallel to the overall monality decline (Smith 1988.Tavlor et al 1998). the reasons behind that decline are ail1 unclear. The central feature behind the controversy is the research of Thomas McKeown. Accordin3 to McKeown ( 1976). tuberculosis was the central feature of the monality decline in Europe. In Great Britain after 1850. there is an apparent decline of mortality from al1 foms of tuberculosis (Smith 1988:1 ). McKeown considered the decline of tuberculosis to be a major indicator of the senerai decline of mortality brought about by rising srandards of living, especiallv improved nutrition. and to have begun pnor to the effects of the nineteenth century sanitary reform movement (McKeown and Record 1962). By the process of elimination of the various possible causes for the decline of tuberculosis monality. McKeown sumised that a risine standard of living. the most notable feature of which was improved nurntion. had played the central role in drivine the decline. McKeown argued that the improvernents of the sanirary reform movement. improved water supply. effective waste disposal. safer food handli- and drier housing have had linle direct bearine on the incidence of tuberculosis. This point has been challenged by other workers (e.g.. Wilson 1990; Schofield and Reher 1 99 1. Szereter 1988: Taylor et al. 1998). who argued that direct social in!en.ention was as irnponant as the indirect benefits of improvements in living standards. Pan of the dificulty in ascenaining the causes of the decline lies in establishing the correlation between the factors thought to be responsible for the decline and the decline itself Sklieown's central problem was the ascribing of relative numerical weights to individual component causes of the monalit?; decline. Even factors such as crowding, a seerningly intuitive indicator of nsk of tuberculosis mortality. are at times dificult to correlate with an increase in rates. For example. in New York City, housing became increasin@y crowded between 1880 and 1900 whiie tuberculosis mortality rates fell sharply (Wilson l990:387). Furthemore. MccKeown's assertion that the deciine of tuberculosis monalitv was responsible for the overd decline of monality in nineteenth century Engiand itseifhas been challenged. His evidence does not demonarate unequivocailv that a decline in airbome diseases. inch- ruberculosis. was the leadin3 epidemiological feature of the penod, or that this decline could be attnbuted onlv to a generd improvernent in diet (Szereter 1988). One argument against McKeown's thesis stems from Arthur Newsholme's view that the most si-dkant source of infection in pulmonary tuberculosis was the consumptive hurnan patient (Wilson 1 990:3 79). Arthur Newshoime ( 19O6b) believed rhat the deciine in tuberculosis monality couid be explained by the increasing segregation of consumptive patient, in hospitais and sanatona. Wilson ( IWO) summarised Newsholrne-s argument and described the decline of phthisis rnonality in Ensland and Wdes from 1838 to 1961 in four distinci and successive phases. intempted by the two World Wars. When ploned logarithrnically. the data for England and Wales approximated four straight lines of increasing sterpness up to 1960 when tuberculosis monality was reduced to a very low level (Figure 1 ). Wilson descnbed Phase 1 as extending throuoh the decades of 1840-70. durin3 which phthisis patients were being segregated in Poor Law infirmaries. Durine this time. linle attention was paid io the iniective nature of the disease. and there was no syaematic attempt to dispose of sputum in a sanitary marner Phase 2 began around 1870. and coincided with L\ large increase in the number of beds available that resulted from extensive hospitai construction during the 1860s There was a corresponding drop in the number of persons receiving outdoor relief (assistancein the forrn of milk or meat allowances). Phase 5 showed an increased and steady rate of decline that continued until the outbreak of World War I in 19 14 Wilson also attnbuted the increased rate of decline to an increased awareness of the infectiveness of phthisis after Koch's discoveiy of the tubercle bacillus in 1882. This deciine was offset bv a rise in phthisis mortality during World War 1, brought on by crowding of troops in barracks and of workers in tàctories. Phase 3 bqan afker 1920 and showed an even more rapid rate of decline than in 1914 This was attributed to the three-fold increase in the total number of (private) hospital beds available to patients between 1911 and 1970. and to the even greater seven-fold increase in beds for tuberculosis patients in public hospitals. The increase in state-tiinded facilities enabled a high proponion of active tubercular patients to be sryegated throughout a greater pan of their illness. The segegation of patients had become more prompt and systemaric by the 1920s; sputum examinations were more readily available; the use ~f the "iron lung" had beyn. and additional sanatona were opened. Phase 4 occurred arier 1947. wirh the availabiiitv oistrepiomvcin and other anti-tuberculosis agents produch a \en. steep esponential decline of tuberculosis monality Wilson also showed that the Iiistop. of the decline or'tuberculosis in Massachusetts and New York was consistent with \wsholmr's euplanatim for rhe decline of tuberculosis in England and Wales. in \ewshoime's vie\\. rubrrculusis did not decline because of an inherent tendency of the disease to decline ncir because ot' the intluence of the social and econornic factors, that deiermined the standard ot' limg To hewsholme. the most important factor in the decline or'tuberculosis is a rrduction in the opponunities for patients with puIrnona- tuberculosis to jpread their infection Lancaster t 1990 29) points out that it is difficult to pinpoint the begjnning of a declinz ot'death rares in a Ion- sequence of rates. However. Newsholme's argument makes sense at an intuiti~e and epidemiological level. althoush his division of the decline into "phases" nrcessitates a somewhat arbitra? determination of the beginning and end of each phase 1.S The Decline of Tuberculosis in Gibraltar in the Context of the Debate Gibraltar presents a unique setting to examine the historical panerns of tuberculosis mondity \\ïth its tishtly controlled rights of residence. the smdy population of Gibraltar may clearlv be deiineated. At the same time. the social environment of Gibraltar seemed to perpetuate a prime condition associated with high levels of monality fiom tuberculosis: its limited space resulted in the endemic crowding that pervaded its entire development as a citv. Significantlv, the decline of tuberculosis monality in Gibraltar may be exarnined in the absence direct measures against tuberculosis throuehout rnost of the study period. and the absence of an? systemic isolation of patients in sanatoria. Despite the Medical Officer's wareness of the seriousness of tuberculosis in Gibraltar. there were no direct official rneasures against tuberculosis t hou-out most of the study period. There was no synematic isolation of patients tri Poor Law Infirmanes and Sanatoria. as in En-land. vet the disease declined from the nineteenth to the twentieth centuries. It would seem that Newsholrne's tt~planationof the declinr of tuberculosis could not be applicable to Gibraltar Could the decline of tuberculosis in Gibraltar be indicative of an inherent tendency for the disease to decline" Tuberculosis was airead! declining in the Jewish communitv in Gibraltar pnor to any efective measures against it ( Hemng 1 987.35) Most of the sanitq and rnedical refoms in Gibraltar prior to 1900 came about because of attempts by Gibraltar's Medical Officers to -4ccording to McKeow's thesis of a sinsle continuous and unintemipted monality decline, the partem of tuberculosis monality decline shouid remain the same for both pre-and-post 1900 periods. Was this tme of Gibraltar? In a studv of the occurrence of respiratory tuberculosis arnong the Jewish and non- Jewish cornmunities in Gibraltar in the late Nneteenth and early twentieth centu-. Sawchuk and Herrinr ( 1984) showed that socio-economic. demofgaphic. and cultural factors could buffer against. or conversely serve to increase. susceptibility to the disease. Sawchuk and Hem- dso demonstrared age and sex differentials in monalitv from respiratoy tuberculosis. with post-reproductive males being at panicular risk. Herring ( 1987) compared the social characteristics of two cohons of tubercular and non-tubercular conjusal families and their relarionship to the wider demographic processes. The overail decline in tuberculosis monality in Gibraltar. however. has never bren studied as a continuous sequence 1.6 The Specific Goals of this Study The present stud~complements previous community-specific and cohon-based studirs by rxamining the patterns of tuberculosis monality of the population of Gibraltar as a ho In addition to the drclinr of tuberculosis monality and its causes. thk studv will also çonsider the mecharustic aspects of the process of change in tuberculosis mortality rates using time-series analysis Both the correlation between vearly ruberculosis monalitv rates as weil as the correlation betwen tuberculosis rnonality and extemal variables will be considered. The scope of this stud!. encompasses a continuous temporal sequence of monality rates from shonly atier the incepiion of the registration of deaths in 1859. to when monality from tuberculosis fell to under one per thousand in the late 1960s. The aim of this nudv is not to enter the debare on the validity of McKeown's emphasis on nutrition as a ma!or tàctor in the decline of tuberculosis. or to argue the benefits of direct social intervention asaina the indirect benefits of improvernents in living standards. These topics have been arnply addressed in the literature ( see previous section). Most explanations of the secular decline of tuberculosis monality " . pits nutrition against public health, living standards a,eainst socid organization. and levels of income againn scientific advance" (Schofield aid Reher 199 1 :7). Schofield and Reher believe that one of the reasons for the polarisation of explanations is an incomplete knowledge of the processes involved. and fùnhemore. that the contrasting positions need not be so exclusive as their proponents seem to suggea. At what point does improved housing and saruration through specific reforms cease to become a result of "direct social intervention" and instead become measures of .'improved living srandards?" A more effective approach to studyine monalitv decline is to examine the specific factors involved in ihe prevention of specific diseasrs. and senerd factors having indirect repercussions on the health of the population. alt hough it mav not have been designed specificslly for that purpose (Chesnais 1991.80) .\lclieouri. in his later work (McKeown 3988.53 ). acknowledged that it 1s dificult to arrive at a precise estimare of the pan played bv nutrition in determining the tiequency and outconie or' infection lt is likely that the influence of diferent causes of tuberculosis monality decline operated at varyin~levels. depending on the timing, of the sents In this thesis the followinp hyotheses will be discussed: 1 the decline of tuberculosis monality in Gibraltar was predicated on local conditions ope rat in^ to influence monality rates. and not on the natural cycle of the disease. operat ing independently of anv human effons; 2 the increasins measures of preventive public health measures at the local level, such as sanitation. housing, and reduction of crowding, as well as direct effons at reducing the spread of tuberculosis played an important role in the decline of tuberculosis monality in Gibraitar. To examine the validity of these hypotheses. the three main cornponents to the research srrateçy are: 1. To reconstmct and descnbe the patterns of tuberculosis monalitv rates in Gibraltar from 1860 to 1967: 2 To modei the mechanistic process underlyine the decline of tuberculosis in Gibraltar usins time-series analysis: 3 To examine the historical contes that influenced or produced those patterns. in order to achieve a better understandine of the causes of decline of tuberculosis mortality in Gibraltar 1.7 Theoretical and Conceptual Framework Sawchuk and Herring ( 1984) commented on the paucitv of historicai information on ihc occurrence of respiraton. tuberculosis in Gibraltar "The available data consists almost rnr~relyof censuses and vital rvents maintained...by the civil authonties of Gibraltar" I Herring 1 987 1) Herring also \irote t hat no persona1 joumals. letters. or accounts were kund describing rirst person esperiences. conceptions of tuberculosis. or social consequences dituberculosis Subsrqurnt fieldnork in Gibraltar bv the author confirmed the lack of direct cr hnographic accounr s Consequently. as in Hemng's study. the prima- source of mortality information in the present wrk is derked from deaths recorded in these re~isters. There is. Iioicmer. a rich source of historical information in the records maintained bv the Medical Officers who were appointed bv the Colonial Government to oversee maners of health and sanitation Their accounts. in the form of Coionial Blue Books and Annual Health Repons. consist of detaiied descriptions of the health and sanit- conditions during their adminisrration. These repons included impressions on the prevahg social conditions and conceptions of tuberculosis by both the administration and the people themselves. and measures taken to arneliorate the situation. as well as statinical summaries. This studv will integrate the accounts of the Medical Officers with the vital registration information to reconstruct the decline of tuberculosis monality in Gibraltar in its historical contes. The advantage of a historical longitudinal study of tuberculosis is that the data may be collected without wairing for the outcome of the disease. as in a long-rem prospective study icornstock 1 986.5) In this thesis. the methodological approach is drawn fiorn the biocultural discipline of medical anthropolog. which is concemed with both the biological and sociocultural aspects of human behavior. paniculariy with how the two interact throughout human history to intluence health and disease (Foster and Anderson 19782). Human behavior piays an irnponant role in changins the ecolo_eical context of the pathosens. .Ant hropoiogists. as professional obseners and interpreters of human behavior in its social and cultural context. play a signihcanr role in ctfons to curb infectious disease problems. or to understand such jucially produced biological phenornena ( Inhom and Brown 1997). Enrichinr explanations of health behavior through descriptions of the cultural ideas and beliefs surrounding those behaviors is an important contribution of anthropolo_qvto infectious disease research. Social scientists have redised that the larser forces of political economy can influence the morbidirv and mondit- tiom infeftious diseases. including tuberculosis. in the individual (Farmer 1997: Packard 1989) The anthropoiogical approach in this thesis is central in the examination of the relationship between mortality and the social reproduction of the conditions that lead to the persistence of tuberculosis and maintenance of hi& tuberculosis monality. In Gibraltar, al1 the factors that served to create or intluence these conditions are rooted in its history and status as a colonial fonress and citv. Gibraltar's epidemiological hiaory is inexrricably linked to its colonial status. Iiom the geo-political location of Gibraltar to its chronic overcrowding and the policies that govemed its population and the construction of itstiuifiaaructure.Fmer ( 1997) suggested several wavs in which anthropologists might make meanin-gfbl contributions to the study of tuberculosis epiderniology: a) by disce- the precise mechanisms by which social forces promote or retard the transmission or recrudescence of tuberculosis; b) by identifvine the buriers which prevent those affiicted with tubercuiosis fiom having access to care. c) bv employing a multidisciplinary approach; and d) by exposing the precise mechanisms by which enrrenched medical inequities are butrressed. The thesis is firdy located within anthropolog in its consideration of the pattern of tuberculosis mortality in Gibraltar in the conte= of its historical political econorny as a colonial citv. and how the colonial forces shaped the experience of tuberculosis of the population. .Along with life-table techniques. the main quantitative method ernploved is rime-series analysis. a usefùl method to identie and describe patterns in time and fiequene-domain data i C hatfield 1996). Time-series analysis has been used extensiveiy in anthropology and histoncal demography to describe and detect any patterns that rnay exia in monality data and to identi- the relationships between them (Galloway 1985. Hajek et al. 1984: Jorde and Harpending 1976. McDonald 1 979. Malina and Himes 1977; Marcuzzi and Tasso 1992: Lin and Crawford 1983. Willigan and Lynch 1982258; Madrigal 1992. 1994). The tuberculosis monality experience of Gibraltar was expressed as yeariy rares. for several reasons: first, because tuberculosis is a relatively slow-acting disease. changes in mortality would be more eEective1y detected in yearly rares: second. breaking down the number of deaths by months would result in exuemely small sample sizes; and thûd; the resuits of this study would be directlv comparable with other studies of the decline. which are based on yearly rates. The small sample sizes also precluded any analysis by districts, or units smaller than the tom of Gibraltar. Therefore. some heterogeneity within the population. such as social class differences, may be losr in ths manner. However, aggregation of the data allowed for modeling of the overail trend and patterns of tuberculosis mortality. CHAPTER 2 GIBRALTAR: SETTlNG AND THE POPULATION This c hapter descnbes t he phyical and demographic setting of Gibraltar. in MO pans. First. the environment of Gibraltar is described in ternis of the geograph!.. geology. and îlimate. which comprise the phvsical setting. The natural physiopphy played an important pan in shaping the character and history of Gibraltar, in that the availability of building-stone and goundwarer resources intluenced milita? fortification and constrained man? of the civil engineering works. Second. the development of the population of Gibraltar Srom the eartiest penod o senlement to the post-U'orld War 11 period is discussed. The contras1 between the rtrerei!. limirrd space ibr building and expansion and the desirabilil! of Gibraltar to immigants due to its importance as a pon and market illustrates the chronicallv crowded environment from wir hm \\ hich the patterns of tuberculosis monality emerged 2.1 Geography and Geology Gibraltar is locared at the border of the continents of Europe and Africa. and at the iunction ac the Mediterranean Sea lvith the Atlantic Ocean (Figure 3). lt is pan of the narrow lberian Penjnsula estendin? southnards into the Mediterranean Sea from Spain. and it is of gctographical and histoncol jigniticance as a strategic milita- gateway to Europe and Afîica. I ts toral length is -:2 iiiiles ( 5 I Lm 1. its ma.imum width is approximateiy one mile ( 1.6 km). and total land area 1s approumately 3 6 square miles (5.8 km2)(Ftose and Rosenbaum 1 30 1 19) There are t hree main pans of the landscape that make up Gibraitar From nonh to south. the!. are the 1st hmus. the Main Ridge. and the Southem Plateau The lsthmus (or honh Front). is a narrow neck of low-lying land rising a maximum of 9.8 feet (3m) above sea-level. Lt extends horizontally from the sheer Sonh Face of the 20 Rock for about 2624 feet (800m),beyond the frontier of the British lines. The Isthrnus joins Gibraltar with the Spanish mainland. Just bevond the frontier lies the border town of La Linea in which live a substantial number of the workers entenng Gibraltar dailv. The Main (or Summir) Ridoe extends fkom the Nonh Face southward for nearlv 1.5 miles (2.5 km). where the Rock of Gibraltar fonns a sharplv ndged crest. This dominant kature of Gibraltar is the "Rock" of isolated dolomite and limestone rising to 139 1 feet (424 meters) above sea level (Wright et al. 1994: 15). The profile of the ndse is aqmmetnc fiom easr to West The eastern side dopes steeply to the sea. Scree breccias and wind-blown sands mcderate the angle of the slope on the lower pans of this side. but the limestone cliffs above this are nearlv venical. Comgated iron sheets cover rnuch of the eastern pan of the dope to form a rain-water-catchment area. The fishine village of Catalan Bay was built on the nonh-eastem side. but no other settlement is possible on the eastem slope The western dope is less steep Sands cover the lower parts of the slope. and on this slope and along the 11 estern coastline the city and dockvards of Gibraltar have been constnicted Tier upon tier ot'duellings was built along the westem slope. extending up about 300 feet above the city. The Southem Plateau is south of the Main Ridge, a gently sloping plateau between 400 and 295 feet ( 130 and 90m) above sea-level leading down to Europa Flats about 98 to i -30 feet above sea-level (X-4Om) Steep cliffs fringe this plateau. where it meets the J lediterranean Sea 2.2 Climate The climate of Gibraltar is Mediterranean. with windy. mild. wet winters, and relativelv calm. hot dn summers (Air Mininry. 19623; Wigley et al. 198 1). The mean minimum and maximum temperatures during the winter months are 54'F and 65'F respectively. and for the summer months. they are 55 OFand 85 OF. The winter season sets in quite suddenly in the Mediterranean where the probability of receiving rain in anv 5-dav period increases dramaticallv from 50-70 per cent in early October to 90 per cent in late October. Prevailins winds in the Strait of Gibraltar and the Alboran Channel between Spain and blorocco are rnainly from the west or east (Air Ministry. 1962:80: Sulman 1976-1 18). The easterly wind is called the levanter (from the Spanish kvmr). Mon rain falls over the fa1 and winter. and there is marked dp season characteristic of the Iberian Peninsula. The hot rnonths of July and Aui~ustare especially oppressive when the easterly levanter strikes the rastern face of the Rock and brings in a heavy. moinure-laden cloud that hangs over the town at times for davs on end Groiind surface condensation from the levanter results in hish humidity at higher eleïations The levanter cloud occurs mainlv in the winter and spring, and liith levanters of about force 3 or 4 The cloud lifts and disappears when the wind reaches hrce 7 or more The shape of the .Uboran Channel causes the levanter to be stronoer at Gibraltar. especially where the Strait is narrowest (Air bfinistn;. l962:8O) The onset of the Irvanter in ts inter rnav bring hea\~rain Stron- levanter mav blow without ceasing for ten days or longer (Air Slinistry. 1962 SO) In the summer. the levanter brin~sfrequent fog and I»\v stratus in the Strait The etfects of strong levanter are especialiy important in Gibraltar. as it creates comples and dangerous eddies in the Bay on the lee side of the Rock (Air Slinistn. i 962:SO). 2.3 The Town In 1704. the British took Gibraltar frorn Spain (Benady 1994). The Spanish laid siege on Gibraltar almost immediately after the capture. followed by another in 1727. Thereafter. there was a period of consolidation of power for the British that lasted until the Great Siege of 1 779- 1783 bv the Sparush French and other mercenaq forces. when most of the orisjnal buildings were destroved In 1822 twenty-eighr administrative areas. or residential districts. were estabtished for better control of civil services These districts were in tum contained within four administrative boundaries. or larser "districts." which corresponds to the natural physiography The nonh districts comprised the area between the nonhem gates of the City proper and the neural remton berneen Gibraltar and Spain. This area included the Colonial Branch Hospital. U'ar Oike letting and hutment. the pumping station. Race Course. rifle ranse. cemetep. slaughter house. destructor and disinfectin5 station as well as Catalan Bay quames and village The central distnct 1s the City of Gibraltar was situated at the foot of the Vain Ridge. on its loiber nonh-\\esrem slope On the east. it was bounded by the rnilitary fence and on the west by the Line Wall its northem limit was the Casemates. its southem. Southpon and Charles \- alThe Town of Gibraltar. the main inhabitable ponion of the Rock. 1s siruated in i he non h-wsr The south districts lie south of these limits. They incfude Alameda Gardens. Saut h Barracks. Rosia. Buena Vista and Europa Point. 2.4 The Population of Gibraltar, 17041867 In 1 701 with the onset of the tweifih Spanish sieee. there \vas a mass exodus of the civilian population of Gibraltar The population estimates for this time range from two to six t housand civilians ( Bradford 1 97 1 16) However. the siege lasted for only a vear. Lrneasy peace prevaiied until European political boundanes were delineated in the Treaty of Utrecht in 17 13. where Gibraltar \vas formailv acquired by the British. With the presence of the British Gamson and the transformation of Gibraltar to a free pon. the civilians gadualiy tricklc J back (Kenyan 19 I I I 10 i Ayala ( 1782) reponed that in 1 771. t he civil population iras only three thousand. tivr hundred of who were Enslish. a thousand Jews. and a large number of Genoese fhere wis anoiher siege by the Spanish and French in 1727. and ünother from I n'q-S.? hi\elson., \icton. at Trafalgar ended tùnher threats of siege to Gibraltar ( Denrus 1 WU I c.4 B\ the tirne the town was rebuilt at the end ofthe Napoleonic U ars. the civilian population \ras rimil!. established. ln 1787. the population was 3386. of \ihom 2 l QO were Ronian ('atholicj The civilian population had increased to 10.136 in 18 14. and 15.480 in 1826 1 Hctnneii 1830 I The war brought an influx of Spaniards and Ponuguese i Haneev 1 9% ) Gibraltar \\as alnicibt tiolh dependent for labor on outsiders. \c ho undertook tasks undesired b!. Gibraltanans. buch as senmts or laborers (Harvey 1996) .At the same time. the rntry of foreigners creared tensions and exacerbated the tembly crowded conditions. Therefore. strict regulations regulated the admittance of foreigners into the city The fira Gamson Orders in existence are dated to 1720. bv which the Govemor had the power to expel aii he did not deem desuable. Regulations were conaantly made with reference to the admission and residence of aliens. The basis of these rewdationswas that aliens had no riats of residence in Gibraltar The mititary expedience was to exclude ail foreigners and to prevent In 18 12 the Xlilitary Police was first established and its most important dut? was to sontrol the admission of aliens and to check over-crowding. Ln 1827. the administration reîùstd licences permitting resident women to marry any aiien males unless the couple subsequently lefi the Gamson. Over-crowding. and its attendant housing and hedth problems prompted the -oveniment io revise the already strict niles resarding irnrni-ration into Gibraitar s there Lbere \*en.limited options to increase housing. policies were airned at pre\.enting the entp. of "unauthorised persons" (Howes 1991: 13 1 ). .A radical reform of the permit system was carried out b\- the Secretaq of State following another rpidemic in 1828 and i he indiscriminare gram O t' permits was entirel- forbidden. .A magistrate was appointed io administer tixed rules on regulatin~admission of aliens and it was found t hat the native Christian population oialien origin had quadrupled in 16 years to 17.000. includinr 7.000 hreigners To keep track of the growing population. voluntaq civil regiaration of binhs was introduced in an ordinancc datrd April 17. 1848. The Census of 1860 listed 15.467 permanent residents. not including the milita? and aliens. which brought the number up to 25.1 79 t Sayer 1 56245s ) ln the 1 860s. the averaee number of foreigners who entered the -zarrison on daiiy tickets durin a rnonth was 19.700 (Sayer l862:46O). Housins problems continued to grow. In 18 14. there were 1664 houses to a population of 9,663. and by 1 87 1 the population was nearlv double but the number of houses had diminished by a third. Eventuaily there was a revision of al1 permits and these continued in force until the passing of the first Aliens Order in Council in 1873. The Aliens Order in Council of 1873 laid down strict mies concerning right of residence in Gibraltar (which meant that as a fonress. no one could clah right of residence). and the binh of children to alien parents (nor permitted) .A series of Alien Orders in Council was laid dom( 1873. 1885. and 1900). By the 1870s. the essential composition of the population had been estabiished. The populace of Gibraltar could be divided into three distinct groups: the permanent ("fixed") civiiian communitv. a large "floating" or transient goup who entered Gibraltar daiiy. and the colonial administration t Sa~chuk1993875). The transient goup consisted mostly of Spanish ~vorkerswho crossed the fiontier daily. and who lefi Gibraltar before the city gates were closed. More than 10.000 Spanish workers crossed the Line daily (Dennis l99O:SO). The crnsus of 1878 lists the permanenr civilian population of 18.011 .At the end of 1888. the total population was 21.467. includiny the milita? The civil population was 18.464. In 1901. the civilian population was 20.355 Three thousand, one hundred and ninety-eisht of these were aliens. with 6.475 rnilitary personnel and an additional 630 people in the port and harbor The Aien Order in CounciI of 190 1 contained a declaration that no person can possess the n~htto enter and reside in Gibraltar. even though a naturai bom subiect of the Crown. withour permission of the Govemor of the Fortress. The total population from the Census of 191 1 was 28. 900. World War I broke out in 1914, and it thrust Gibraltar back hto the role as a rnilitary fonress. this tirne to prevent submarines from getting into the Meditemanean and out again (Dennis l99O:41 ) Economic conditions deteriorated afler a brief boom brought by war work. and many Gibraltarians moved across the border to La Linea where it was cheaper to live Regulations penainins to right of residence in Gibraltar continued to be extremely stringent. However. as long as relations with Spanish authonties remained cordial, several thousand Spanish workers could cross the border daily, and Gibraltarians living in La Linea could work at home. In 1911. the civilian population was 1.000. and in 193 1. it was 2 l,j 72. Instability came arain to Spain when the Spanisii Civil War broke out in 1936. Nearbv San Roque became a tiont. and there was fightins iust across the border in La Linea ( Dennis 1 990:44 ) Large numbers of refugees fled t O Gibraltar. .4s rnany as 1 0.000 refugees camped on land in the isrhmus. and even afier the situation in Spain stabilised. some 2,000 rerlgees. which included dispiaced Gibraltanans, continued to stay (Dennis 1990:45). Followine- the ourbreak of the Second World War. miiitary functions and needs became pnorities once more in Gibraltar In Mav of 1940. most of the civilian population (main]! n-omen and children). was evacuared to England. Nonhem Ireiand. Tanger, and Jamaica Only 4.000 persons engased in defence works and essential services remained on the Rock (Dennis 1990 1s 1 Repatnation beoan in 1944 and gradually the civilian population was re-established (Finlagon 199 1 ) The culmination of the Second World War marked the end of Gibraltar's significance as a military fonress. Xo further census was taken until 1951. The total civilian population then was 20.815 ln 1967. the total civilian population of Gibraltar was 25.281. Dunng this time. uneasy relations with Spain openly deteriorated again. after the pubiication in 1965 of the Spanish Red Books alle@ne British breaches of the Treaty of Utrecht (Dennis 199059). The disputes culrninated in the complete closing of the border in June of 1969 This chapter is presented in two sections: first. the sources of demographic. mortalsty. and historical data will be discussed; second. the cnteria used in determinhg tuberculosis deaths from the registers will be explained. The second section includes a discussion on the nature of the recording of tubercuiosis monality statistics, as well as some possible sources of error in the recorded number of deaths. 3.1 Sources and Types of Data Used The data used in this thesis consist of censuses. death records and govenunent docuinents. which were ootained by Dr. LA. Sawchuk and students. including the author. during various field seasons from the Goverment Archives and Reeistq Office in Gibraltar. Since 1974. Dr Sawchuk has built a subnantial and evolving database of historical matenal, civii registers. and censuses. with assistance from students. From these are denved monality information. population at nsk. residential information. and historia1 contextual information. 3.2 The Census The earliesr population figures given in Chapter 2 came fiom estimares by his~orical observers such as Ayala .A systernatic fom of census takins did not exist until 1868 (Hemng 1% 4 The ( 'r~>srr.sqrhr l'optlut~o~~(lrdrirmcr was passed in 1868. and the method of compiling census repons has remained relatively constant since (Dennis 1990:79). From 1 S7 1 until 193 1. the British milita- and their dependants were excluded fiorn the census i Dennis 1990:78). There was no census in 194 1. The next census was in 195 1. In this census. the families of the military personnel were Uiciuded but not the servicemen themeives 29 (Demis 1990: 78). In later censuses ( 196 1 onwaràs). the following categories are empioyed in enurneration: Gibraltar-bom. British (other than Gibraltarians and families of British semicemen). Visitors. and Transients. The Govemment Censuses provide information on the age and sex composition of the population at rkk. The nominative infornuirion recorded on tach census consists of age. sex. relationship to head of household. religion. binhplace. occupation. and length of residence in Gibraltar Retums for seven census points have surMved in varying States of compieteness: 1868. 187 1. 1878. 159 1. 190 1. 1921. and 193 1 (Hemng l987:42). Three censuses. 1868, 1 878. 1 59 1. were transcribed from paper copies of the original censuses into a computerised database Fisures for the other census points were derived fiom the Blue Books and Annual Colonial Repons. Inter-censal population estimates were obtained using exponential interpolation. lnterpolation was applied to age-goups (apgregates) as opposed to single ages. as this method is more reliable for populations that have significanr age fluctuations produced by fenilit y. milration or monality ( Arriaga 1 994:34). Exponential interpolation was applied instead of linear interpolation .Uthouah the two methods produce sirnilar results if the dates berween the census points are close. linear interpolation will produce hi_eher values for points iùn her apan t han esponential interpolation lnterpolation figres were obtained by a modification of the spreadsheet developed by the CS Bureau of the Census (Amiaga 1994). 3.2.1 Consistency of Census Dain The populations at the census points of 1868. 1878. and 189 1 were checked for anv inconsistencies by exarnining the various age groups by year of binh, unng a modification of the spreadsheet developed by the U.S. Bureau of the Census (Arriaea 1994). The figures are plotted for five-year cohons and show how the population bom in the sarne penod of years and enumerated in each successive census is reduced through rime. This method allows for detection of trends of fertility, monaiity, migration, ase misreponing. or errors in census enurneration. A iine represents each census. Parallel tines indicate the reliability of the census information. The spaces between each line represent changes in each cohort throush the inter-censal penod. In a population that was closed to mieration. anv chanses in spacing would represent the reduction in the cohons by deaths dunng the inter-censal period. Figures 3a and 3b show the age structure bv year of birth for the three census points. bp ses The pattern of the lines shows that the differences between the population at each census point are due mainiy to monality in the younger ages during a senes of epidemics from I SNto the 1890s The line for the Census of 1868 shows that the population under 18 sutfered increased monality in the years that preceded the census. for both males and fernales. The age goups 13 and under in i 578 show the effecrs of the extreme stress faced by the population that year. including a srnallpos epidemic from 1878-90 The line for the Census of 1898 shows the effects of a smallpox epidemic from 1883 to 1884. and a senes of measles epidemics from 1887 to 1 894 bv the a_ee groups 13 vears and under. There is no disruption b'. larse migratory movements Aithoueh there were a large number of workers entering daily from Spain. rheir presence and length of aay were strictly monitored. The census structure retlects the permanent civilian population. and long tenn ~empora~y"migants. Once the conditions of the consistency of the censuses were satisfied the figures for the population at risk were derived from a combination of censuses and interpolation between census points for each vear of the anaiysis. fiom 1860 to 1967. These figures were broken down into the following categones: males. fernales and the overd population. 3.3 Civil Registration of Deaths The pnmary source of mortality data is the Ordinary Civil Regstration of Deaths. The records are available from 1859 onwards. Death registration was not compulsory until 1869. An Ordinance of November 13. 1868 made the registration of death compulsory, effective lanuary 1. 1869 These registers provide information on monaiity by age. sex. cause. residence at tirne of death occupation during the penod of 1860 to 1967. The cause of death was recorded under three categones: general. prima. and secondary. Two advanrages of ths continuous registration system are: 1 ) intonnation is available on an annual basis. and 7) long-term trend information may be obtained. ln 1887 hnher amendments were made to compulso~registration of binhs and deaths bv the Orditmrcr ro CumoIi&te and .-îrnr~tdthe lm:s Xrl~irrtigro I 3.4 Estimating the Numbers of Deaths from Tuberculosis from the Registers: Some Considerations 3.4.1 Tuberculosis in Historical Records In historical records. consumption. phthisis. decline. wasting disease. delicaq of lungs are vanous names for tuberculosis. "Atrophy" and marasmus also includes cases of tubercular origin (Puranen 199 1 :99).Many deaths actualiy attributable to tuberculosis were pro bably reponed in these cateoories. There may have been a tendency to list tuberculous deaths as bronchitis. pneumonia whoopin_g cough. or influenza (Bryder 1988:104: Smith 1988:12). In the Gibraltar Blue Book of 1882. cases that showed spptoms that resembled tuberculosis of the iung were attributed to illness caused by "inûarnmation of the lungs." The stigma anached to tuberculosis also resulted in the victirns themselves concealing this disecise and of label lin^ it as catarrh or bronchitis (Dansey-Browning 19 18). There may also have been a tendency for physicians to ofer a diagosis more acceptable to the patient to avoid losing that patient to another physician. or sirnply not to report the case out of compassion for the victim (Bryder 1988: 106). Nevenheless. an examination of the death records and the Annual Health Repons show that tuberculosis was recognied as an imponant cause of death. The Medicd Officers of Gibraltar encourageci the svsternatic treatment of "persistent colds. or repeated attacks of "bronchitis". which may indicate an early stage oi tuberculosis (Fowier 1909). The yearly General Sratement of patients adrnitted to the Civil Hospital mentions the "laqe proportion of cases of Consumption of the Lungs which are brought to Hospital.. " (Barker 1822) 3.4.2 lncompleteness of Notification The mors introduced by the dificultv in diagnosis were compounded by social factors Herring i 1%-1 discussed the difficulty of obtaining an accurate account of tuberculosis monalitv liom historical records. and some of the factors that operated in Gibraltar that contributed to the distonion of that picture. One of the main sources of distonion is due to the incompleteness of notification. One of the indicarors of incomplete notification is that man? cases of the disease reach a late stage before being notified (Bryder 1988 104) This is suszested in Gibraltar bv the fan that many cases were not reponed until the last stages of illness or until accidentai discover-y by medical or sanitary officers. Underreporthg of tuberculosis was also caused by out-migration to La Linea. The Annual Repon of Health in 19 1 1 reported that besides the cases in Gibraltar. another 76 cases were estimated arnongst natives of the Rock residing in La Linea, known as the "east end" of Gibraltar. filled with many of the poorest people (Fowler 191 1). The higti costs of rent and provisions in Gibraltar forced some of the poorer residents to find homes outside of Gibraltar, and notifications of tuberculosis among them were not included in the retums (Dansey- Brownins 1914). Since there was no systernaric rneans of keeping track of these people. rhere is no way to determine the amount of out-migration of tuberculosis cases to La Linea. Herring ( 1987:52) noted this vicious cycle. If the breadwimer of the family fell il1 with tuberculosis and was unable to work. the family faced poveny. Families with no means of support were driven out of their tenement in Gibraltar and were forced to seek refuge in La Linea Convenely. some who fell il1 and lost their employment retumed to Gibraltar for the various kinds of charitable assistance available (Dansey-Browning 19 14). The Annual Repon of Health of 1908 estirnated that the number of notifications rnultiplied by ten or twenty nould -ive a more accurate picture of the extent of tuberculosis in Gibraltar. Thus. the evidence shows that tuberculosis was more prevalent in Gibraltar than the data would sursest. .Uthoueh there is no wav of accounting for the number of deaths in La Linea. or to determine the extent to which tuberculosis deaths were diagnosed as deaths from other causes. reasonably accurate estimates can be made by taking into account the cnteria used in the historical diagnosis of tuberculosis (Hemng 198752). CHAPTER 4 ANALYTICAL METHODS This chapter provides an overview of the analytical procedure. There are two components in the analysis l Yearly ( crude) mortality rates; 2 Age-and-ses specitic monality rates The vearly monalit y rates were analvsed using gaphical met hods. and time-series analysis. \{,hile the age-and-ses specific monality rates were analysed using Me-table techniques The steps taken in each analvsis will be discussed in detail in their respective 4.1 Choosing the Period of Study The beginning of the period of study. 1560. marks the era immediately preceding the iniplrmrntation of cornpulso~.regisrration of deaths. The study period encornpasses two rnaior periods of Gibra1tar.z monality histop the period of high background monality and epidernics before 1900. and the monality transition to lower monality rates atier 1900 Linrteen sisty-seven \Las chosen as the terminal date of the srudy for two reasons: first. ruberculosis monality rates Iiad declined ro emerneiy iou levels bu 1967. and second. in the pcriod tbllowing 1967 the border between Gibraltar and Spain \vas closed marking a new period of deteriorating political relations. In the cafculation of the yearlv monality rates from 1860 to 1967. there are two penuds where data were missing or unavailable. Data were rnissing from the registers for pan of I S76 (probably an artefact of record keeping. and lacking tiom the period of 1940-44. as no records were kept when the civilian population was evacuated from Gibraltar at the besinning of World War II in Europe. For the analvsis. missine data were replaced by interpolation tiom adjacent point S. This method. rather t han replacing the values wirh the overall mean. was chosen because it is more appropriate when each obsen;ation is closeiy correlated with the previous observation (StatSoft 1995:3321 ). For the calculation of the age-and-sex specific monality rates. age-specific monaiity information ivas available on& from 1860 to 1939. Funhermore. the number of ruberculosis monality dearhs was too small after 1939 to permit calculation of age-and-seu monality rates. The discussion of specific age-and-sex monality rates. wtile framed in the conrext of the \r.hole studv period from 1560 to 1967. will only refer specificaily to the aforementioned 4.2 Calculation of General Mortality Rates and Tuberculosis Mortality Rates \iPearlyrates 11 ere calculated for senerai monality. overail tuberculosis rnonalitv. pimonan. i respiraton. i tu berculosis. non-pulmonary tuberculosis. and ot her respiratory diseases. including brcinchitis Each set of rates was calculated for the overall population. and hy ses Information riom the prima? source of monality data. the detailed death records of Gibraltar. lias used in conjunctlon with the comments recorded in the Annual Health Repons ro compile a continuous timr-series of yearly overall monalitv. tuberculosis monality. and ot her respiratop disease rnonality rates from 1 860 to 1 967 These rates were also checked against the rnonaliry rates published in the Annual Health Reports. when available. The yearly death rates sere calculated to describe the overall pattern. secuiar trends. and to esamine an! changes in rnonality in specific years. 4.3 Tinte-Series Analysis- Studying the Yearly General Mortality and Tuberculosis Mortality Rates .A combination of the graphical approach and time-series methods is used to analyse the yearly mondit? rates The graphical approach is an effective way of depicting the overall pattern of the data. Time-senes analvsis allows the researcher to mode1 the process that produces the pattern by specieins the factors that contribute to the behavior of the senes and analyse how these factors interact to influence the direction and magnitude of the senes (Lin and Craw-tord 1983 37 It can be dificult to associate monality decline with a panicular social e,.rnt Funhemore. an! sequrnce of rates or events mav contain svstematic bias. large tluctudtions. or other sources ai error that obscure the "tnie" behavior of the mortality phenornenon under coiisicirrarion Time-series analysis is a usehl technique thar takes these potenrial sources of cunfusion inro accounr when descnbin- and analysing data containing c hronologically ordercd uixen.ations on a quantitative charactenstic taken at different points. or intrn-ais ICliR and Hliggett l 147. Chat field 1997:1 1. Time-senes methods also allow the researcher to euaniinc tliz etfects or' an' event on mortaliry rates by cornparing the sequence of obsen-ationb~çiorr: and aiier rhe event. Such observations or measurernents There are threc i~i:iim«ntirnr-series patterns (Hoff198;) I Overall trend. \ihich refers to the overall movement (change in overall mean) of the senes in an!- direction. i . e . . upwards. downwards or horizonrally fiom the beginnins to the end of the series: 2 Seasonal pattern. which is a repetition of the same basic pattern at regular intemals. and 3 Cyclic pattern. which is a consistently risin9 and falling pattern (peaks and valleys J The distances between the peaks and vallevs need not be equal. .An' or al1 of these three patterns ma? be present in the same time-senes. These pattern cm generallv be recognised \isually in a gaph, but may be obscured by random variation or other sources of enor The basic cornponents of anv tirne series are: Time series = Patterns - Random error This is represented as Y, = FI - ci In the case of rnonalitv rates. t he premise is that rnonaiity at anv given time penod ma? be jiatisticall?. relarçd to nionaliry in êarlier periods. The soal of time-series analysis is. theret'ore. to estimate the magnitude of the I.; and C, components in order to obtain the most iikrl? representarion of that series I-, for I less than or equai to n represents the fitted 1 estirnated, values for the series 1.1 is subtracted from .Y, to obtain the error term et for n r ri The computed error terms are called residuals .An accurate estimation ofx, contains the \iiiallest p~~ssiblritlrror rttrm wth tmi? randorn residuals ( Hoti 1983 ) 1.3.1 The Coiicept of :i Deterministic Trend 4s descnbed III the previow section. the overaIl trend refers to the overall movement ichangt. in overall riieani oi the jeries in any direction. Le.. upwards. downwards or horizontall?- from the beginning to the end of the series .A description of the trend itself, hotbel er. makes no assuniptions about the forces that dive it. .An\.staternents about the inherent nature of a trend. such as a natural tendency to drcline. must be referred to as a drrrrmutrs~zctrend. If tuberculosis were inevitably declining regardless- of anv human effons. then any tirne-series mode1 that accurately describes that process would include a sipificant detenninistic trend parameter. The lack of a determiniaic trend in a mode1 of tuberculosis monality decline would siynifL that the decline in monalitv over time depends on extrinsic factors (e.g.. improvement in sanitation. reduction of nsk factors). rather than on a '-narural" tendency for monality to decrease over time. 4.3.2 Box-Jenkins Method The time-series method used in this thesis is the univanate Box-Jenkins approach. Bos and Jenkins ( 1976) developed a class of models (ARIMA models) that can be used to describe the behavior of man? ditferent types of tirne-series. and a practical procedure to select the most appropriate model Madrigal ( 1994) outlines several advantages to the Box- Jcnkins approach in the srudy of mortality First. it takes into account the correlation between the points in the data set (senal correlation). Ordina? lem-squares regession assumes that the data are uncorrelated. i r . that each data point is independent of the previous point, Hoivever. this assumption is seldom met in time-series data such as yearlv monalitv rates (Lin and Crawiord 1983 47 ) Serial correlation ma! intlate the standard errors of ordinary least squares parameters estimates by as much as 50 per cent and as a result. the statistical signiticance of an impac? is correspondingly overstated fklcDowal1 et ai. 1983: 13 1. Second. .ARlhl.-\ models are consr ructed empirically riom the data. Third. only a few parameters are needed to describe even highl? comples dara. Therefore. very parsirnonious models can be developed Parameters in the Mode1 The acronvm .NMA refers to the types of parameters used in this approach: autoregressive (AR) and moving average (MA) parameters (Pankratz 1983: 5 ). The autoregressive pararneter is a coefficient or a set of coefficients that describe how each observation in the series is related to each previous observation. The interval between one observation and the previous one is called a lag. In this analysis. the position of the 1% will be referred to as its ordrr Therefore, lag 1 (the intenal between one observation and the one immediately before it) will be called its first order lag, and so on. Modifjine the basic description of a tirne-series given earlier. this can be summarised as: Wherct 5 = a constant ( intercept ). O!.@ are the autoregressive parameters. and (t- 1 ) and (t-2) refer to the la-. The parameter 0 is constrained by -]< al< -1 a,- @ . -1 @-O,* -1 T herefore. in a t ime-scnes of yearly monaiiry rates the autoregessive pararneter describes the monalitv rate of each year as being made up of an error component E and a linear combination of prior monality rates (an AR model). The moving average parameter describes the process where each observation in the series can also be afectcd bu past error that carmot be accounted for b!. the autoregressive component (StatSofi 1995 i Where I-/ is a constant and W. 6 are the rnoving average parameters. The parameter 8 is constrained by -1.. 8,.- - 1 8,- @\ -1 6-fp -1 1 n a rnoving average ( \ 1.4 1 niodel. t hen. each monaiity rate is made up of an error component e and a linear combinaiion ot' prior random past error .An important rrwrenient in Bos-Jenkins analvsis is that the time-series under consideration be statwrian t having a constant mean and variance through tirne) This means that the trend or variance iias to be accounted for in the model. since mosr tirne-series will not be stationap- Most srries \dl also show strone senal correlation Stationaritv rnay be achieved by differenciiig t lie srries or taking the natural logarithm (Madrigal I9W438). Ditferencing ~illreniai r the trend component and the strone senal correlations. Diferencine transfoms the senes by subtraction t rt- xt.l ) This means that the monality rate at year 1 is subtracted from the monalit!. rate at year 2. the monality rate at year 2 is subtracted fiom year 3. and so on. Differencing mav be repeated until the series is stationap. .a.MA. .WMA i sontaining both autoregressive and moving average parameters) or .ARiMrZ (autoregressi\-einte~rated moving average) models may be eaimated. The Box- Jenhns notation (p. d. q) will be used in this analysis where p refers to the autoregressive parameter. d is the number of times differencing is carried out. and q is the moving average parameter For example. a mode1 (0.1.2) means that it contains no autoregressive parameters and two moving average pararneters that were computed for the senes after it was differenced once ( StatSofi 1995-8) JI ode1 Selection: Autocorreht ion and Partial Autocorrelations In order ro estimate the parameters that will best describe the tirne-series of monality rares the most likely .AR andjor MA components must be selected. This is achieved by esaminin%the autocorrelation (XCF)and partial autocorrelation (PACF)bnctions of the jeries The plot s of these îünctions are then compared with theoretical models t hat indicate :ne most likely underlvin- rnodel of the senes. They also indicate if the series must be dirferenced or rransformed before estimation of parameters The correlation values show how 'trong the serial correlations are at each lag For each autocorrelation pior the correlation i aiiirs at each lag and their standard mors are shown The limits of 2 standard errors are snotvn Estimated autocorrelation tirnaions that lie within the ~2 standard mors are not jtaristicaliy ditierent r han zero at a 95 confidence level. The size of the aurocorrelation is miponant in the analys. one is interested usuall'; only in very strong (and therefore very ~ignitïcanr1 autocorrelations ( StatSoH 1995 :3272). The panial autocorrelation hnction is another indicator of serial correlation. The dirference between the autocorrelation and panial autocorrelation functions is that al1 the correlations of the obseneations within the las are panialled our to show oniv the main correlations (StatSoft 1995:3372). This provides a clearer picture of any arong senal Identification of the plots in this thesis was based on five basic models outlined in Hoff 1983: McDowall et al. 1983; Pankratz 1983; SPSS 1993 and StatSoft 1995. The general euidelines used in this analvsis are: 1 1 One autoregressive (p) parameter: ACF - exponential decay; PACF - spike at las 1. no correlation for other lags. 2. Two autoregressive (p) parameters: .\CF - a sine-wave shape patrem or a set of exponential decavs; PACF - spikes at lags 1 and 2. no correlation for other lags. 3 One rnovine ave-e (q) parameter: ACF - spike at lag 1. no correlation for other lag. PACF - damps out exponentially. 4 Two movin- average (q)parameters: ACF - spikes at lags 1 and 2. no correlation for other lags: PACF - a sine-wave shape pattern or a set of exponential decavs. 5 One autore~ressive( p ) and one moving average (q) parameter: -\CF - exponential decay staning at lag 1; PACF - exponential decay startins at lap I (Source: StatSofi 1995) The autocorrelation tùnctions of al1 autoregressive processes should (theoreticaily) decay iowards zero. either by a simple esponential decay. a damped sine wave. or more compiicated decay and wave patterns I Pankratz 1983 : 127) In practice. however. autocorrelations computed from a senes csarnple autocorrelations) can only approximate the theoretical patterns presented above (Hoff 1 983 ; Pankratz 1983;StatSofi 1 995). Therefore. there it is possible to find a non-zero sample autocorrelation where is it zero on the theoretical autocorrelation. Furthemore. significant lags could also occur by chance (StatSofi 1995). In this analysis. an autocorrelation was considered sigdcantly different from zero if it was larser in magnitude than twice the standard error. Estimation of Parameters and Fitting the Mode1 The parameters were then estirnated by using the ARMA procedures in the Tirne Senes module of STATISTICA~' (Version 5.1 1SM), which tests for statisticai significance between the estimated and observed series. Paramerers were accepted only if they fulfilied the stationarity requirement This means that 0 and 6' values were accepted only if they remained within the consrraints of - I and + 1 . The statistical significance of the esrimated coeficients of the parameters are evaluated by calculatino the t-value by testing the nul1 hypothesis Ho. estimated cortficient=O: t=(estimated coetficient 1-( hvpothesised coefficient value) estimated standard error of the coefficient .hv coetficient with an absolute t-value of 2.0 or larger is significantly different from zero at rou-hl- the 190. or p-level of 5 05 The p-level represents the probability of error that is involved in acceptin~the observed value as valid (StatSofi 1995). A p-level of 05 indicates that there is a 5% probability that the observed value or relationship occurred by chance alone. and that there is a OiOO probability that it is valid. or "si_Mificant." A coefficient with an absolute t-value of lrss than 2.0 was excluded; including coefficients with absoiute t-values less t han 2.0 tends to produce non-parsimonious models (Pankratz 1983 202). The fitted model was then checked by examining the residuals produced by the fit. The process is repeated until a satisfacto- fit is achieved. A model was accepted if the residuals contain no systematic patterns. The two moa important criteria in detenùiing the adequacy of the model are (Hoff 1983): 1 . the AR fitted values fulfil the srationary requirements, and 4. the computed residuals are unrelated to each other. 4.3.3 Measuring the Impact of Historieal Events on Mortality Once a suitable .ARMA mode1 has been determined. the impact of any events. or "intemiptions" in the series can be tested and measured. This is done ro assess which historical events had a measurable impact on changing tuberculosiç monality rates. .An event is an); qualitative change chat cm be in the form of introduction of a treatment program, enactment of new laws. or other such chanse (McDowali et al. 198364) tn this discussion. the evt :it will be referred to as an "inremption". as the andvsis is usuallv called hrzemrpred .41UMi-1 The procedure consists of testins the nu11 hypothesis of whether an event had an effect on the time senes 4 '\lcDowall et al. 1 983 : 10). The process is visualized as. Each o is a vearly rnonalitv rare. and .\' denotes the event in question. This is written as- xi = brrc + bpm + O Where Si = the t,h obsenmon b,, = the pre-interruption series level b,, = the post-interruption series level 6 = an error terrn associated with St In some cases. the etfect of the interruption is obvious. as in a dramatic fa11 or rise in the level of the series. In other situations. the effects may be less obvious. Nevenheless. even if the impact of an interruption is obvious. the analysis can be used to estimate the maginide and form of the impact (McDowail et al. 1983: 10). Figures 4a,4b, and 4c: Types of Possible Impact Patterns impact Pattern. Abrupt/Permanent Time Figure -la Impact Pattern. AbrupvTemporary Time Figure 4c Figures 4%b. and c show three types of impact patterns that are possible. An impact is measured in terms of its onset and duration. The impact of any event may be abrupt or -gradua1 in onset and ether permanent or temporas, in duration (McDowali 1983:66). .An abrupt, permanent impact pattern (Figure 4a) implies that the overall mean of the time-series shified fier the intemption (StatSofi 1995). This shift is denoted by ti. An abrupt. ternporaq impact pattern (Figure 4b) implies an initiai abrupt increase or decrease, which then decays without permanently changing the mean of the series. The impact ar the time of intemption is denoted by O The impact after the intemption is denoted by 6. The rate of the decav is determined by 6 If 8 is near zero. the decay will be quick and disappear after only a feu observations If O is close to one. then the decay is slow and the effect of the interruption will be evident over many observations. A gradual, permanent impact pattern f Figure Jc) is defined also bv two parameters 6 and 0. When 6 is close to zero. the end of the permanent effect of an impact rnav be seen after only a few observations When O is closer to one. the permanent impact will be seen &er many more observations. 6 and B were estimated usin the Interrupted MUMA module in STATISTICA (Version 5.1). Estimates of6 were accepted only if the absolute values remained between zero and one. As defined by XlcDowall et al. ( 1983 1. the 6 rnust be greater than zero but less than unity 0<6<+1 Given the fluctuation in the tuberculosis monality rates. it was difficult to specie a porf the expected pattem of an intervention component. To determine the appropriate type of change at each phase. the procedure suggested by McDowail et ai. ( 1994) was followed. First. the analvsis was staned with an abrupt. temporary intervention component. If the eaimated vdue of 6 did not rernain with the bounds of stability as described above. an abrupt, ' Select tentativetirne- 1 -1series rnodel based of 1- 1 .-\CFand PACF Plots l l Estimate the BOX- ! parameters of the model Assessin2 the impact : of historical Etvents on tubercuiosis I morralit t. Examine Effects ) of Interruption Figure 5: Outline of the Time-Series Analysis temporary pattem was ruled out. A gaduai. permanent impact was then tested. and 6 subjected to the same criteria. If 6 was rejected. then the onlv remaining pattern was an abnipt. permanent pattern The significance of 6.1 was indicated bu the t-value described in the preceding section. Before accepting an impact assessment. the same 'diagostic checks as in the ARIMA modeliing was applied the residuals to indicate that there were no patterns present. Only evenrs occumne ailer 1869 and before 1958 were assessed using this method as the prosram requires at least 10 observations before and after the interruption (StatSofl 1999 1 The steps taken in the rime-series analysis are summarised in Figure 5 4.4 Life-Table Analysis- Measuring Tuberculosis Mortality Differentials by Age and Sex When considering the influence of social and other environmental factors on tuberculosis rnonality it is vital to examine the a_ee and sex patterns of tuberculosis deaths over time i Puranen 199 1 1 O 1 ) The age-and-ses pattern of attrition from anv cause of death may be measured b!. esamining its relationship with overall monalitv using multiple decrement life table methods Jlultiple-decrement life tables take into account two or more rypes of anrition \\orking together. as opposed to ordinq life tables (Namboodiri and Suchindran 1987.92). T~someasures of a-e-and-ses dityerentials were obtained: 1 the probability that a person will eventually die from tuberculosis. and 2 the increase in expectation of life resultins corn the elimination of tuberculosis. The steps taken in the analvsis are I computing the ase-specific and age-and-cause specific monality rates 2 constructing an ordina? life-table using the age-specific death rates (for 211 causes combined) 3 distriburing oftuberculosisdeathsineachage~oupin thelife-tablepopulationobtauied previously 1 computiq the probabilities of dying from tuberculosis in each ase goup 5 constmcting the decrement (cause-deleted) life table 4.4.1 Age-Specific and Age-and-Cause Specific Mortality Rates The age-specific tuberculosis monaiity rates were computed using the number of deaths from tuberculosis in each interval and the base censiis population classified by 5-year age goups For the interval (.r, . x,.,) the age-and-cause-specific monalitv rate M,a. for cause 6 was obtained bu- w here L) ,r is the nurnber of deaths occumne From cause 6. 1' is the base census population. and k is an arbitrary constant ( in t his case 1000) i rnodified frorn C hiang 1 98-1 i The se-specific rnonality rates for al1 causes cornbined for the same interval were computed as rC. multiplied by the ratio of al1 deaths to the corresponding base population (Namboodiri and Suchindran 1981 94) 4.4.2 Ordinary Life-Tiible and the Probability of Dying Ordinary life-tables were constructed according the method outlined by Chiang ( 1984) for al1 causes of death combined usine the LifeproTM program (Sawchuk and hthony 1989). Overall life espectancies r, and overall probability of dying q, were obtained from these tables. The probability of dving from a specific cause 6 at each age interval (w,. x,., ) was then obtained bu: w here: U,6 is the number of deaths occumng fiom cause 6; LI. is the number of deaths occumng from al1 causes: q; is the overall probabilirv of dving. and k is an arbitra- constant (in this case 100) The catije-specific probability oî'dyine is defined as the probability that an individual will die riorn cause b afrer sunnins ro ase x. but before reachins age x..i 4.4.3 Cause-Deleted Life Table Analysis One way to masure the impact of a disease on a population is to consider the effects oi the eradication or' rhat disease In demographic terms. one ma- focus on the net probabilities oEsuni\ai until a gi\ en age or of dying in a siven ase interval. given survival to the be~inningof that men-ai ( \amboodiri and Suchindran 1987 1 O3 ). Cause deletion. or elimination. ma? be drtined as the net probability that a person dive ar the beeinning of age inten-al (.Y . .Y. -.- \r il1 die behre rrachiny the end of that intenal. if the risk of dying fiom a speciîic cause d is rernwed (\aniboodiri and Suchindran 1987:103) Under the assumption t hat the diverse causes of deat h act independently of one another. the respective forces of rnonality mav be visualisrd as where p& is the force of rnonality due to cause 6 and p&x) is the force of monality due to all other causes combined. If the survival probability when the onlv cause of death 6 is 6 0.the additive forces of mortdit- are: The relationship between the sunival function for cause 6 and the ordinary life table function is. L~x,. .)iis(.~.) = [I(x,- .)/I(x,)lR H is the force of monality in a givrn age interval that is approximated by the corresponding a--specitic monality rates rll. and deaths Dy: R = 1 .r ,.* 1.U . 1 Mr= , -r,-" ID-r. i( 1D.r i rnodified t'rorn Namboodiri and Suchindran 1987:104) Therefore. from the ordinan. li fe-r able for al1 causes cornbined the survival probability for cause 6 ma? be estimated. and the corresponding life expectancies obtained. Life espectancies \\ith and without cause Ù can be compared to show how severe cause ô is in the population INamboodiri and Suchindran 1987: 105) CHAPTER 5 RESULTS This chapter presents the results of the analysis using the methods described in the previous chapter. There are two main sections in this chapter. The first deais with the analysis of the various sets of yeariy mortality rates. and the second. with the analvsis of the age-and-sex specific monality rates. In the fira section. the gaphical and time-series analysis is presented. This section consists of a) a discussion of the trend and overall pattern of the yearly monality rates as revealed by the graphcal analvsis; b) modelling the processes that create the trend and overall patterns in the monality rates usiny the Box-Jenkins time-series techniques; and c) using the models from the Box-Jenkins analvsis to examine the impact of independent events on the yearly monality rates The second section presents the analvsis of the a--and-sex specific monalitv rates. using life-table techniques This section consists of a discussion of a) the use of age-and-sex speciiic monality rates in the construction of life-tables to obtain the general probabilitv of dyins. and probabilities of dying from specified causes: b) how probabilities of dyin_e from specihed causes can be used to construct cause-deleted life-tables: and c) the differences between the male and femaies patterns of probabilities of dying. 5.1 Graphical and Time-Series Analysis 5.1.1 General Mortality in Gibraltar: Trend and Overall Pattern The general Ions-term direction of the monality rates is represented by the secular trend. In this manner. chanses in monaiity rates followine a secular trend are differentiated 55 fiom shon-term fluctuations about the mean (Lin and Cradord 1983 :38). To detect the presence of a secular trend. the series of mortality rates was ploned and exarnined. The fira step in the anaiysis was to remove any extreme values, or outlien. from the series because outliers can make it dificuit to detect the presence of a trend.' Figure 6a shows the initial plot of the monalitv rate from al1 causes from 1860 to 1967. One extreme peak representing increased monaiity From the epidemics is especially prorninent: the choiera epidemic of 1865 increased the overall mortaiity rate that year to 57 per thousand. This outlier was rernoved from the final analysis since exploratory anaiysis showed that its inclusion affected the fit of the trend-Iine. Even with the outiier removed. it was difficult to see the overail behavior of the rnonality rates and determine the trend. Therefore. the series was first transfonned by smoothine to reduce the variance about the mean. Simple exponential smoothing was applied. as this technique allows for the inclusion of a general parameter alpha (a)which controls the tveight given to recent observations in determini- the overall level. When a=l. the sinde most recent observation 1s used exclusively. when a=O. all obsenations cary equal i+eight t SPSS Manual 19% 29 ) The parameters used were determined tiorn the data using a parameter grid search procedure (StatSoft 1995) From each a the resulting residuals (obsewed values minus smoothed values) were calculated and the combination which yieided the smallest residual variabilin was chosen. An a= 430 was used to smooth the data. Figure 6b shows the gaph of the srnoothed overall mortality rates, with the y-axis plotted on a semi- logarithrnic scale The semi-loearithmic scaie stretches out the scde as it descends to zero, because the death rates between I and IO are ploned on the same distance as rates between 10 and 100 (Cliff and Haegett 1988: 153). Figure 6a: General Mortaltty Rate: Gibrattar 1860-1 967 Figure 6b: Expanentialty Smoothed Genenl Mortalrty Rates Gibaitar 1860-1 967 58 The overall monalitv of Gibraltar appears to have foiiowed a pattern of decline where the overall level of monalitv dropped. followed by a period of fluctuations. then fell again. The overall trend is curved. rather than iinear. and is best show fitted to the observed rates by a poiynornial funaion. Sharp deciines. each followed by a period of flukuations occumd around 1878. 1903. and 1939. representing the three major periods of charge in overall monality The first period of decline extended through 1878, where the fitted curve shows clearly the transition from the period of earemely hi& mortality from the epidernics in the early 1860s into the 1880s where mortality was still high and epidemics still rampant. but lower- than previous levels Mer this period of exrremely hi@ monality. the monaiity rate never rose above 30 per thousand again. .A penod of fluctuations followed the fira decline. This period marked the beginnin- of another senes of epidemics. and rnonality rates tluctuated between 16 per thousand to around 26 per thousand. There was another senes of smallpos epidemics 60m 1578 to 1579. 1880. and 1883 to 1884. .eiorher cholera epidemic struck in 1882 Two vears later there was a measles epidemic. followed bu another tiom 1 S90 to 89 1 and the iast in 1894 The earlv penod of high monality with erratic peaks of monality due to epidemics of infectious diseases are characteristic of the monality regime preceding the modern decline and is considered a period of high background monality containin- episodes ot' "crisis monality" (Sawchuk 1993. 1996:Tavior et al 1998:Vallin 1991) The second sharp decline in overaii monaiity came around the tuni of the 20~century. By 1903. the monality rate had dropped permanentiy below 20 per thousand. Although monality rates continued to decline overall. a series of fluctuations began after the sharp decline and lasted through the 1 93 0s. The be-annino of World War II marked the last sharp decline in overal mortality rates during the penod of study Civilians who were not engaged in essential wartime occupations were evacuated to England. Jarnaim and Nonhern Ireland. Althouoh the sudden decline of rnonality rates ffom 1939 to 1945 is an artefact of the evacuation. it is clear that monality rates were considerably lower af3er World War II when monality rates dropped below 10 per t housand. 5.1.2 Tuberculosis Monality in Gibraltar: Trend and Overail Pattern Establishng the trend and pattern of the eeneral monality rates provides a context within which to examine the trend and pattern of the overall tuberculosis monality rates. Figure 7a shows the overail tuberculosis monahty rates in Gibraltar from 1860 to 1967. Like the general monalitv rates. the tuberculosis rnonality rates show a senes of fluctuations about the mean To minimise the effect of the tluctuation of values. the tuberculosis monality rates from Gibraltar were ploned on a serni-lo~arithmcscale on the y-axis (Figure 7b). The series lias drst smoothed to reduce the confbundine effects of year-to-year- vanation on the secular trend The resufting plot shows t hat the decline of tuberculosis monality rates over the nudy period. like the overall monaiirv rates. also occurred in a series of rapid declines followed by fluctuations. There were three major periods where the overail level of mortality dropped. foiiowed by a period of fluctuations where rates rose slis@tly, then fell again. Figure fa: Overall Tuberculosis Mortalrty Rates. Gibrabr 1860-1967 Figure Tb: Exponentially Smoothed Overall Tuberculosû Mortality Rates GIbraitar 1860- 1967 The hi@est level of morrality from niberdosis occurred at the beginnine of the study period. The rnonality rate of tuberculosis fell from tive per thousand in 1860 to two per thousand in 1577 .4lthou-h dunng ths penod there were no specific measures by the Govemment to deal with the treatrnent and isolation of tuberculosis cases. the eeneral measures instituted in response to the hirh overall rnonality tiom the epidemics could also have had an effect on reducing the tuberculosis monality rate. These measures included improvements in sanitation and water supply Accordins to Szereter ( 1988) improved sanitation water suppiy. and other public health measures that reduced overall monality could have had a seconda? effect on the decline of ruberculosi-; The first decline nas followed by a period of fluctuations in the tuberculosis monality rates. brpinning arourid I S7S and extendin until the early 1900s Throu~houtthis period. ruberculosis monalit! rates tluctuated between 3 6 and 4 per thousand Tuberculosis monaliiy rose sharpl' in I SiS. and increased correspondingly with the choiera epidemic of I SS' and the srnaiipo~epidemics in 1 SS7. 1890-91. and 1894 The early W: cent ury sau anot her decline. where tu berculosis monalitv rates dropped belou I 2 per ihousand This decline could be in pan be attnbuted to measures hcilitatins removal ai cases of infectious disease from houses. as well as to some official artrmpts to address the problem of tuberculosis infection. Between 1893 and 1907, several b+la\rs wre passed tu address the problem of removal of these cases. Athough tuberculosis \ras tiot specifically targeted. the Annual Repons of Health at this time indicate that the Jlrdical Otficers uere wil aware of the relationship between overcrowding. removd of infected persons. and tuberculosis Measures aimed at detection and isolation of tuberculosis cases becamr officiai in 1906. when notification of tuberculosis became compulsoq. This second decline was followed by another period of fluctuations in tuberculosis monality rates that began afier 1906. when declining econornic conditions were felt in Gibraltar As in the previous periods. although there was a slight increase. the rates never exceeded the highest value of the previous period. The last decline in the study penod began in 1939. when overall tuberculosis rates had begun to faIl below one per thousand. World War II intempted this decline. with the evacuation of the civilian population. Followin_pa gradua1 repatnation that staned in 1944 and lasted until 195 1 tuberculosis mortality rates continued to decline riom around 1955 throucrh- 1967 The use of mass radiography afier the war facilitated the discovery and isolation of active cases A volunta? detection scheme was instituted in 1957. aimed at detecting tuberculosis in foreign workers. This was made compulso~in 1964 In 1966 tuberculin testin- of school entrants was staned. Extrernelv low nurnbers oideaths marks the end of the senes By the 1960s. some vears reponed no deaths from tuberculosis. O~.erall.the pattern of tuberculosis monalitv decline closely resembles that of the grneral decline in monaliry rates Before 1940. the overall trend shows a similar curve to that of the overall monality. but the curve is less pronounced than thar of the overall monality rates. indicating a more gradua1 decline However. afier 1940 there is a sharp drop indicating the post-i\ar decline of tuberculosis This post-Worid War II drop in rnonaiip rates is similar t o t hat obsened by Wilson ( 1 990 1 in the data for England- and Wales. 5.1.3 Pulmonap and Non-Pulmonary Tuberculosis iMortality Patterns Jlost of the decline in tuberculosis monality was due to the fall in puimonary tuberculosis rates (Fisure 8 1 The decline of non-pulmonary tuberculosis rnortdiry is graduai. Figure 8: Overail Pulmonary and Non-Pulmonary Tuberculosts Mortalfty Rates. Gibraltar 1860-1 967 40 1 1 r 1 - I 1 1 1 1.. -- Non-Puimonary Tuberculosis '?4r;, Pulmonary Tubercuiosrs Figure 9: Comwrison of Tuberculosis and General Mortality Rates 1 - Overail Tuberculosis Mortalw Rates ------Generat Monality Rates Non-pulmonary tuberculosis monality rates remained more constant following the period of fluctuating rates prior to 1900. never rising above one per thousand. The sudden innease in 1897-99 is a probable artefact of diagosis. Fifiv-four out of 174 deaths listed as ~iberculosis that period were attnbuted to milia? tuberculosis Out of the 54 deaths from miliary tuberculosis. 2-1 were from ases under 25 Miliarv tuberculosis is an advanced tom that may represent reacrivation of latent cases (Lancaster 1990 82). It is likely that manv of these deaths were actuall!. froni the pulmonary catesory The concurrent decrease in pulmonary tuberculosis dunng that penod supports this observation 1.-omparison between Tuberculosis. Overall Mortality Rates and Other Respiratory Disenses FigureC 9 show the overall monalitv rates plotted with the tuberculosis monality rates The plot show the similarities between the tu.0 patterns. each going throueh a senes oi'periods oideclinr ibllwrd bv tluctuations and another decline Both series show clearlv tlir sharp drcline atisr W~rldb'ar II To examine how closely the decline in tuberculosis nionaitty tri Gibraltar 1s relateci to the overall monality decline. cross-correlation functions benseen the residuals rio111 the tittrtd niodels for the tuberculosis rnonality rates and the overail rnonali t!, ratrs tim aii causes wre computed using the standard formula: for t= 1 to n- I and t= 1 to n- 1 whrre s-bar is the mean of the overall mortality rate and y-bar is the mean of the tuberculosis death rates (StatSofi 1995). The cross-correlation values represent the de-<: of correiation between the rates of each year both series Lag O refers Figure 10b:C- Fundion of Residmis Overall Tubercubsis Mortday Rata8 and Gemmi Mortility Rates P~b1900 Figure 1Oc: Cross-Comtatm Function of Rcsiduaîs Overall Tukrculosis Mortality Rates and Geneat Mortality Rates Post-lm to cornparisons between the sarne year. lag -1 refers to a cornparison of one year to the previous vear. and lag 1 compares the value of one year to the nem. The residuals £iom both series were used instead of the original senes as the large autocorrelations with each untiltered series could result in spurious large correlations (Chatfield 1996: l39), Figure 1 Oa shows the correlation values and their standard errors. The dotted lines mark the range of two standard errors. The decline in tuberculosis monalitv in Gibraltar is highly correlated with the general decline in death rates. as shown bu the hiehest value at lag 0. and is statisticallv signiticant at the .O5 level. Athough the exact nature of the interaction betseen different disease organisms is still unclear it has been shown that there is some link betwen peak of monalit' from diseases such as cholera and corresponding monality from tuberculosis (Hardy 1993 220 ) To determine if the correlation between overall monality and overall tuberculosis monaiity \vas constant throughout the penod of study. the sarne cross-correlation function \\as calculated for pre-and-post IWO penods Figres I Ob and 1Oc show that the significant correlation between the patterns of overall monality and tuberculosis monalitv rates is tnie oithe period of high monality before 1900. but afier 1900 no significant correlation exists. Another imponant factor that must be taken into account in the analysis of ruberculosis monalit?. rates is monaiity tiom other respiratory diseases. notablv bronchitis and pneumorua .At its ped. respirato- diseases other than tuberculosis accounted for 2 1 percent of al1 deaths in Gibraltar The causes of reduction in deaths from non-tuberculosis respiratory diseases are obscure and just as cornpiex as that of tuberculosis. but some of the factors that intluenced the deciine of one ma- also have influenced the other (Hardv 1993:2 15). During the intluenza pandernic of 19 18. the contribution of respiratory diseases other than tuberculosis went up to 30 percent of al1 deaths. Figure 1 la shows the monaiity rate from respiratory diseases plotred with the monality rate from tuberculosis The peak From the influenza pandernic of 19 1 8 stands out clearlv in the respiratov series.' htil the 1880s. the monality rate from respiratory diseases rose in counterbalance to the decline in tuberculosis However. after 1 885 and until the tum of the century both series showed a similar decline Both patrerns were also noted in the data for England and Wales (Hardy 1993 2 15 I When plotred separatelv the monaiitv rates for pneumonia and bronchitis show n similar pattern (Figure I I b j 4.1.5 Diffeerence Between Male and Female Overall Tuberculosis Monality Rates Figure 12 show the male and female tuberculosis rnonality rates tiom 1860 to 1967. The ses ditference i Fly-r I ;ai \tas measured bv taking differences (hl-F) instead of ratios, brcause during somr \cars. iio tuberculosis dearhs were reponed for females and a ratio would have resulred in di\-ision b!- zero This approach was used by Madrigal 1 1997) in drai mg u it h zero \alues \\ lien ccilculat mg sex ditferentials The plot shows t hat males esperienced a higher monality rare hmtuberculosis throu-out the period of studv although there are somr years in panicuiar brfore1900 that femaies show higher monality. This is show also \then une wmparcs the male-female differencrs for pulmonan and non- pulmonan tuberculosis monality t Figure 1 3 b 8: 13c ). -4dditionallv. the plot shows that the magnitude of male-frmalr monality diffèremes fiom pulmonary tuberculosis did not begin to fa11 until aiier the i %Os but non-pulmonary tuberculosis differences staned to decrease earlier Figure 1 la: Cornparison of Tuberculos~sand Respiratory Disease GIbnltar . 1860- 1967 - Overail Tukrcuiosis -*---- Respiratory Disease Figure Ilb:Broncnitis and Pneumonia Monarrty Patterns Gibraîtar 1860-1939 Figure 12: Male and Femaie Tuberculosis Mortality Rates Gibraltar. 1860-1967 Figure 13a: Sex Difference inTubercutosis Monaiity Rates. Gibraltar 1860-t 967 Figure 13b: Sex Oifference in Pulmnary Tubercuiosis Rates Gibraltar. 1860-1 967 Figure 13c: Sex Differencein Non-Pulmonary Tuberculoss Rates Gibraltar. 1860-1967 5.2 Box Jenkins Analysis The sirnilaritv between the eeneral rnonality patterns and the tuberculosis monality pattems suggests that sirnilar processes shaped the two senes. TO identi. these processes. Box-Jenkins the-senes modelling was applied to the senes of monality rates. The followhg section will discuss the procedures followed in modelling the behavior of the mortality rates. The seps in the Box-Jenkins analysis are reviewed below: i ) plot monality rates. 2 ) calculate and plot the autocorrelation ( ACF) and partial autocorrelation (PACF) functions. and select a tentative model based on the ACF and PACF plots; 3 ) estimate the pararneters of the model; and 4 I check the adequacv of t he rnodel. Since the modelling process is iterative. each estimation procedure may require multiple plots of the autocorrelation and autocorrelation fùnctions of the series and of the series' residuals. To illustrate the process. .-\CF and PACF plots will be presented in the modeiling of the general mortality pattern. and the overall tuberculosis pattern. ln order to avoid intempting the discussion with multiple pases of ACF and PACF plots. subsequent ACF and PACF plots will be included in the Appendis 5.2.1 Modelling the General Mortality Pattern Earlier examination of the plot of overall monality reveals an outlier in the mortality rates. caused by an increase in monality during the cholera epidemic of 1865. Outliers can seriously affect the .4RiMA procedure; therefore, when the cause of outliers is knom it should be removed in order to model the "normal" behavior of the series (McCleary and Hay i 980; Hoff 1983; SPSS 1993). Before applying the Box-Jenkins procedures to the dat4 the outlier was removed and the missing value substinited by interpolation fiom adjacent points. .b examination of the autocoaelation and partial autocorrelation plots of the series (Figures 14a & 14b) reveals a high degree of serial correlation. The series is not stationary and mua be differenced. in order to evaluate the number of parameters to be eaimated. The autocorrelation and parial autocorrelation plots of the differenced series (Figures I4c & 14d) indicate that a moving- average model might be suitable to descnbe the senes. but the pattem is complicated bv large autocorrelations zt lag 5 and 6 Since any seasonal pattems in the data would have been subsumed in the yearly rates. these la- were moa likely random and not si-gnificani To stabilise the senes' variance, the data were los-transformeci. The series was then re-diferenced. The plot of the autocorrelations (Figure 14e) reveals that a movine-average model is indeed suitable; the laree autocarrelation at Ias 1 cuts off to zero. The partial autocorrelation function (Figure 14f) decays after lag 1. .J. tentative mode1 of ( O. 1. 1) was estimated .A moving-average parameter (0 = 44, p<. 05) was eaimated. The residuals were then examined to check the adequacy of the model. The two important assumptions of the .UüMA mode1 are that the residuals should be normally distributed, and that the? should show no serial correlation. Both conditions are met (Figures 15a & 15b. Figures 15c & 1 Sd) The random distribution of the residuals indicate that 1 ) no more tems nerd to be added to the equation; and 3) there are no unusual or unaccounted for patterns in the data (Lin and Crawford 1 983 46,) The moving average model that describes the pattern of the overall monality rates may be written as: Figure 14a: f unctum of Gen«al~Rabs -.-.--. - . -- -- . :,a4 3 " ...... -..;...... 4. - . ;935 - ...... &...... j ....-....-116.2 -.- - . 936 ...... A ...... ' --L. - ...... -'.;'.: . j3,': ...... ---. *.- - ... -- . --.-,?A ...... i ...+...... 3~5.3 . 1913 W...... &...... 3:: .- . foyi ...... i...... * ..... 236; 2;- ...... +...... 4 -- . . . ,1699 ...... -S. . -39.; ...... 'v.: m. - ...... -...... : ...... 4--.- - . - . .- . .-..-- - ...... - ...... & ...... -;;+. - : Figure 14b: Partial Autacarrelation Function of the General Mortalrty Rates ..:- .... "-...... '."""...... ;i; ...... j...... - - - ...... -.--.....-...... *...... - ...... ;...... ------..*...*...- * ...... A- . - - - ...... - ..jP_ ".+...... ---r- ...... -- ...... *++*...... ,...... -... - -- ...... c, -..... ;-.---.-.-...... **.*...... - - - ...... --...... - . 4c- M...... Figure 14c: Autocorralttion Fundon of Diffaremad Gemmi Mortality Rates Figure 14d: Par(lal Autocorreiation Function of the Diifferenced Geml MortalQ Rates . .-- ..-#y,J ,. rn...... <...j ...... i...... ;-...... --.....-.- ic. *; 18. 5: . ;Jdg ...... ;...... il; r...... -.- . :344 " ...... i ...... ;- ...... m..; ...... i...... ;o. :o . : q;; " ...... i ...... j..m...... ; ...... i...... - a 2: .Q? ---- .1- -.y.:= m...... - ...... ;i ...... ; ...... - -4 . oc . a:'--- ,...... ; ...... :im ...... ; M 3C. 34 . . a-;--- ...... ,.-;...... q ...... i ...... j ...... 3i. 55 .-.. . - ---...... i ...... ; ...... *..;.,,,...... :.,...... & 3:. oc . ..-.r- - ...... -i ...... ,-i ..... 1...... i.- 36, 05 . ;?:...... L ...... i...... m.;...... i ...... --.-.----. 32 . 55 - -- . -*,a ...... ;.-...... -...... --- 35. 5: . -.- ..y ,; 2 ...... i...... i ....i ...... ;...... -. 35...... P...... ! ....i ...... i...... - js.9,: . uoj ...... ; ...... , i pi ;...... - jo. ;- . -. -* -- . ---.- ...... -...... ,.....*...- 2=. Q2 : I: Figure 141: Partml Autocomhtion Funcbon of Log-transfomied and Differenced G«mal Mortafw Rates Figure 1k A- Function of ARMA (0,l.l) MoifiW Rm Figure 16b: Parbol A- Fundkri of AR lMA (0,l.1 ) Rasiduats of Genaral Mortality Rates -. - ::z:. -.-.- t 4 -se- ...... i...... *.:...... ; ...... - . .. - t...... ;...... + ...... *.;...... i...... - .-~-*,- -- ...... *...... - * -- . -y? ...... +...... ,...... *...... -...... -..~...~~...~ . - -- .. y= p...... """"...... ~...... *...- - -- . a- * ...... *...... +...i*..i...... *...--.--..-..*.-...*....- . . -- ..*y ...... **...... i...--...-...... -. - -- . 'C ,...... *...... ;...... -...-.-....-- - -- ...*c ,...... *...... ~ - .- .. - ."" ...a.. "...."...... 8. .*...... -..*...... -...... --.-a - -- '...... -.....-*.----.-.**- . .,?C ...... *...... ; - -- . -*yo. ~.....-..-...... -..-..--.-..*.*...... ; +...... ; ...... - - -- ... "."""".""'."..... -06 -05 -04 -03 -02 -01 0.0 01 02 03 04 05 06 07 Normal Upper Boundanes (xc=boundary) Figure 15d: Normal Pfobabiltty Plot of AR IMA (0.1 .1) Residuals of General Mortalw Rates Value The moving-average parameter is an estimate of the degree to which the overd rnoRality rate in one year is influenced by conditions amilar to those operating in the previous year. At the same time. the high autocorrelation at the first lag is also indicative of a the-trend (ClSand Haggett 1988:15 1 ). Some have considered the long-term trend of decline of tubercdosis as pan of the natural cycle of the disease, essentially unaided by human efforts (Comaock 1986). A significantly large trend parameter, or constant, in the model would indicate the presence of such a trend The analysis showed that the mean value for the differenced senes was not si-gnificantly large (i.e..pater in magnitude than twice the standard deviation of the diferenced series divided by the square root of the nurnber of data points in the differenced senes). A constant term. or trend parameter, therefore. was not included with the model. The trend parameter is only included in the model when the mean value of the senes is significantly larse (Hoff 1983 134) This indicates that the time-trend for the overall rnortaiity series is not a dettrrmlrltst~crrertd 5.2.2 Modelling the Overall Tuberculosis Mortality Pattern The autocorrelation tùnctions for the time-series of the overall tuberculosis rates (Figure 1 6a) show strong serial correlation. Serial correlation is arongest at the first las and remains strong with consecutive lags. The partial autocorrelation function plot (Figure 16b) confirms the strong autocorrelation at las 1. The plot shows that the largest value is indeed at la- 1. and the rest of the correlation functions are not significant. The strong serial correlations also indicate that the senes must be differenced before proceeding. The series \vas differenced once. Each rate now represents the difference between the original monality rate and the one before it. The series is stationary derdifferencing once. An examination Figure la: A- Function of Tu- Moitility Rates Figure 16b: Partrai Autocaneiation Fundion of Tuberculosw Mortaîii Rates Fqun 1- AutocornWh Fun- of Differenced Tubeculos#i Morhlity Rates - -- - - .---." . . ;c--- -...... i ...... :...... j ...... Le.:: .-c'-: ; .; >- 1 -. :32 . i.94 ...... ,...... --.-mi ...... -...... - a,. ., . b.2Ll -- . - - *,- - -.,f5 :?;J W...... ,...... -...... - ...... i ...... - -0.- " . ,- '2L' '-' . , . -- ,...... A.*...... -.b...... 1 -I *m.:- . 1 ?J .: ...... ; ...... - 3û.CS .SOOC --- -- .- 5 -4 . ..-....- ...... 4...... im ...*..; ...... 4 ...... 2- ..* . ,000 --- .- - - -...... ".*....-"..""'...... -2-. c <--. . ---. . 4:: ;lj . :ooc " ' --...' - - - ; . --,= ...... ; b;...... : ...... :I2:: -. . -. i L ...... * --*. - - .- .t . S...-- ...... m...... ,-.. -- . - ..- . - 4- -..- a* A...... ' d - ): *--- - a il ; - .._...... -- -. - -- -- . - -. -. - . ---...... -- ...... ;'...... -...... * Zr.-- . .CUL . . -- . - .- ..*..* -- -.rai ...... i.... { ...... ;...... ; ...... 3s.:: .:ci92 ...... -- - -- ...... - ..; ...... - . - -- . -1002 . - . ..- r -6- ...... -...... <...... a -- - a--. . 33.6 ..:JO2 . --. -- -- ...... -.....1...... -- -. 2- . -a...... 4 12. : , 1; ;> 'j . - . . - ...... _.__.__...... a..-...... -. .TV . -- .- 7---' . - ,- 'L 4 Figure 16d: Pamal AutowmF unebon of Oifferenced Tuberculosis MortalQ Rates - - .-.-.. . + -* - . -..- - - .-- - ...... ..... -7 -.-3: . Figure If c: Histogram of ARIMA (1 1 .O)residualç of Tuberculmis Mortality Rates -20 -16 -12 -08 -O4 0.0 04 0.8 12 16 2.0 2.4 Expect* -18 -14 -10 -06 -0.2 0.2 0.6 10 14 18 2.2 2.6 Normal Figure 17d: Normal Probability Plot of ARIMA (1 1 .O) residuals of Tuberculosis Mortality Rates VALUE of the autocorrelation and partial autocorrelation functions after differencing (Figures 16c & 16d ) indicate that a tirsr order autoregressive model I1. l .O) wouid best describe the overall tuberculosis monalit! The estimated AR parameter O= - .38. and remained within the constraints of - 1 and - I The absolute value of t= 4.21 and was siwificant at the pc.05 level. The autocorrelation and panial autocorrelation plots of the residuals (Figures 17a & I7b) show that none of t he residuals are significantly correlated to each orher. Figures 17c & 17d shows the normal distribution plot of the residuals. Thus. the AR model describing the overail tuberculosis rnonality rates of the Gibraltar may be wntten as: accord in^ ro Stroup et al (1 988). the autoregresive parameter is an indicator of how the nurnber ot'déarhs in one penod (month or vear depending on the series) depends to somr estent on the number of deaths in previous penods. The degree and order of dependency is sho~n b?. the las This shows that the overail tuberculosis mortality rate fiom one year is most strongl! aifected by the monality rate tiom the preceding year 1t also shows thar high levels of tlucruation in As in the model for the senerd monaiity rates. the constant term was not significantly large and \Las escludçd from the mode1 The lack of a deterministic trend and the inclusion of an autoregressive pararneter of the first order in the series indicate that the nature of the declinr of ruberculosis monality was throu- a successive senes of short-term reductions intluenced by exremal factors such as living conditions and improvements in sanitation. This is contr- to McKeo\m's thesis that the decline of monality occurred spontaneousiy, uninfluenced by medical or health measures (Wilson 1990). A more appropriate description of the process would be a series of local changes in the mean of the series (asopposed to a determinisic change t hroughout J. with a non-deterministic trend t hat is updated throughout the whole series (Chatfield 1996.227). The autocorrelation and panial autocorrelation plots for male tuberculosis monalitv rates (Figures la & 1 b. ~ppendis)show the same hi& degree of autocorrelation. When the series was diKerenced once. the aurocorrelation and partial autocorrelation plots indicate that a moving-average process misht best describe the data. The autocorrelation ibncrion (Figure Ic. .-\pibendis) cuts ott' ro zero aîier the first lag on the negative siae. and the partial autoc~rrelation (Figure Id. Appendix) hnction decavs to zero. However. two autocorrelations lie just bewnd the two-standard error line. Since such a pattern is not espected in yearlv. a~crcgated-- data (Lin and Crawfbrd: 36). it is likely that the pattern is not significant. and is ;i iiiu~~dhi \.ariance in the data. .Accordin&-. the series was log- transformed to reduce variance. and re-diferenced. The autocorrelation îùnction now presents a clearer picture of the process underlying the data. with the large negative autocorrelation ai la2 i thai curs otf to zero (Figure le. Appendis) The partial riutocorrelation tiinciii~riplot i Figure 1 t: -4ppendiir) also shows that the Iag two large autoc~rrelat~onsare iioi~no ionger present at the larger lags. .A movinp-average model t O. 1.1 ) was then cnosen. and the parameters estimated at 8 of 45 (PK 05. absolute ~5.08). .A check of the residuals îonbrms that the model is correct. There are no si-gificant panem present in the autocorrelation and partial autocorrelation plots (Figure 2a 6: Ib. .r\ppendix). Figures 25 & 2d ( Appendis shou the distribution of the residuals (the negative values are a product of the loyransformation The model is written as: The autocorrelation and partial autocorrelation plots (Figure 3a &-3b. Appendix) of the differenced overall monality rates for females also indicate that a first-order rnovins averase process could be used to descnbe the series. The large autocorrelation function at lap 1 cuts off at zero and the panial autocorrelations decay to zero. Although there is a large correlation value at las 6. the plots show that it does not repeat at subsequent lass and is t herefore of no practical significance (Hoff 1983 : 180) .Accordingly. a model of (O. 1.1) was twrnîted at 0 = 45 (P< 05. absolute t=5.O). The autocorrelations and partial autocorrelations of the residuals (Fiyre 4a & 4b. Appendiu) show no significant patterns. and are normallv distributed (Figure 4c B Id. Appendix) The pattern of tuberculosis monality rates tbr females can also be written as. The incorporation ot' the moving-average process indicares that the number of deaths from ,in\-. xar 1s intluencrd to sume extent bu the same stresses or factors that influenced mortality 111 the preceding >.car i Madrigal 1994 247) The sirnilarir> of coefficients for both males and females indicate that the same year- ro-year variation in eiivironmental (physical and social) conditions. are important in intluencinp the overall pattern for both sexes. These conditions refer to any circumstance. such as the level of crowding that affects infection or re-infection. In other words, the coeficients are a measure of the conditions that infiuence exposure to the tuberculosis bacillus. Such conditions. in turn. operate on personal factors such as age at infection sex. age. and size of the infeaing dose to produce differences in patterns between males and females (Lancaster 1990:9 1 ) Males and females respond differently to comrnon conditions that influenceci rnortality (Wilson 1990:380). Therefore. the same movinggaveragemode1 cm be used to depict both male and femaie tuberailosis monalitv pattems. although the monality rates are lower in fernales 5.2.3 Modelling the Pulmonary Tuberculosis Mortality Pattern Figure 18a shows the pulmonary tuberculosis monality pattern for males There are four extreme monality peaks in the earlv pan of the series ( 186 1.1863.1 866. and 1 867). each followed by a significant drop The high values mav be attributed in part to the hi& mortaiity from epidemics during that penod. the most notable beine the cholera epidemic of 1865. In the previous section. it was shown that there is a hieh degree of correlation between the vearly monaiitv values There could also be a higher degree of recording error in these values. as compulsory registration of deaths did not take place until 1869 These outliers would int roduce a strong "seasonal-' pattern to the autocorrelation values. For the purposes of t he Bos-Jenkins procedures. t hese values were substituted by interpolation of values from the adjacent points The outliers u,ere later re-introduced into the analysis to assess their impact on the pattern of monalit! rates Lin and Crawford ( 1983) followed a similar procedure in modellins yeariy monality figres for ltalian and American cornmunities. Figure 1 Sb shows a plot of the monality rates for pulrnonary tuberculosis in males after removal of outliers. The piot shows that the series would need to be differenced. as there is a change in mean level. most noticeably in the series aer 1939. The autocorrelation and partial Figure 181: Pulrnonary Tuberculosts Mortalrty Rates in Males Gibraltar. 1860-1967 Figure 18b: Pulmonary Tuberculosis Mortality Rates in Males. wth Outliers Remwed autocorrelation plots c Figure 5a 8: 5b. Appendix) indicate that a moving-average rnodel would best describe the series The autocorrelation tùnction has a large spike at lag 1 and culs ofFto zero. and the partial autocorrelation hnction shows decaving pattern Both are nesarive. indicating rhat 8 is larger than zero. A modei of (O. 1.1 ) was tentatively chosen and 8 of 63 (P< 05. absolute t=S 61 \vas estimated. Plots of the autocorrelation and panial autocorrelation hnctions of the residuals (Fisures 6a Br 6b. Appendix~reveal that there are no sigificant patterns The nomai probability plot of the residuals show that cluster around a straight line and are normally distributed (Figure 6c & 6c, Appendis) The mc .iel can be 1~ rit t en as Figure 19 shoiis the pattern of monality from pulrnonary tuberculosis for fernales. The monality rates tiv tlir iiimales do not show the same degree of fluctuations in the eariy pan of the series. althougii tkrnaies experienced high monality from pulmonary tuberculosis durmg that iimr. as did the niale= The series \vas also tit to a moving-average model: afker diferencing once. the ploi iir'iiir dutocorrelation fiinctions (Figure 7a. .-\ppendis) shows a large negativr value ;ir las 1. and other lags cul off at zero The panial autocorrelations i Figure 7b. Appendi.; 1 decrrasr arier the first Iag. The estimated coefficient for an (O. 1.1 ) niodel \\as 8 = 01 1 i 1' 15. riosolute t=? O ) heither the autocorrelations nor partial autocorrrlat ions of t hr residuals \i ere sipificant (Figure 8a & 8b. Appendis The residuals irerc also normally distributed ( Figure Sc & 8d. i\ppendix). The rnoving-average model for pulmonan tuberculosis in kmales ivas written as: The results of the ARMA analysis show that shon-term processes influence both male and female pulrnonav tuberculosis mortality rates. The nroneest factors that influence tuberculosis monalitv are events or circumstances occumng in the preceding year. The risk of active tuberculosis is greatest shonly after infection and "people who develop the disease shonl~afier infection are likelv to be.persans in whom the promoting factor was present pnor to infection" (Cornstock 1986:1 1 ). Therefore. although the conditions predisposing a person to infection or re-infection may be longterm. the conditions hastening death from active infection may operate relatively quickly. The estimated duration of life afier the onset of active tuberculosis is on average twenty-three to twenty four months (Hardy 19932221 Enrinsic factors such as occupational or other risk factors can shonen this to between three and eighteen rnanths (Hardy 18% 223 1 5.3 tnterrupted AR1$1.4 One of the ditficulties in analyses of tuberculosis monaiitv patterns is that it is difficult to rivaluaie rhr link between changes in monality levels and factors that may raise or lower them i Hardy 1993 220) These factors include epidemics of diseases such as cholera social and economic conditions. or etions specificallv aimed at reducing tuberculosis rnonality. A senes of histoncal evcnts \vas incorporated into the model of tubercuiosis monalitv to assess an- impact on the rates thai might br rneasurable There are two ob-iectives to this analysis The first is to assess the impact of extemal events on tuberculosis monality rates. and second to see if these events mi@ represent points of chanse that correspond to the beginning or end of different periods of chanse in tuberculosis monality descnbed earlier. Chatfield (1996:128) suggess that wherever possible. extemal knowledee of a given context should be used in deciding where change points (changes that atfect the mean or trend) have occurred in the data. The impact of any event. therefore. was not considered in isolation or necessarily as the sole causal factor. but was examined in the conte= of the surrounding histoncal circumstances of the event as weil. The results confirm that abrupt. permanent changes occurred during the senes of declines of tuberculosis monality rates. Several abrupt. temporary impacts were also identified within the periods of fluctuatins rates following each deciine. The transition from the initial decline in the tuberculosis monality rates occurred in the 1870s. .An abrupt, permanent chanse in the mean level of tuberculosis rates occurred after 1878. The parameter b= l 752 was rneasured III the change in the overall tuberculosis monality rates. 1878 uas a "period of high ecological stress" in Gibraltar. identified bu Sawchuk i 1 993 1. t hat had a signiîïcant impact on the overall level of monality. The "period of high ecological stress". as detined by Sawchuk. was a year of extremelv low rainfall. associated itith iower life expectanc!. a change in the seasonal pattern of monality. and increased monality due to diarrhoeal diseases This was a year of overall high background rnonality. .A smallpos epidemis \ras aiso reponed that year An examination of the monality rates sho\vs that monality frorn tuberculosis increased bv 1.79 per thausand during that year. There was a large rfièct on male puimonary tuberculosis rates (&=l.37. p< 05)The nature of the change (abrupt. permanent indicates that despite hi& fluctuation in rates during the penod following 1 SÏS. the mean level of monalitv was chanune pennanently. refieaing the decreasing trend. hhile the effects of the hi&-stress year of 1878 were not in themeives permanent. the mean level of the monality senes changed permanently afier that year. In the periods of tluctuations followin~the declines, the fluctuation of tuberculosis rnonality rates was measured in abrupt. temporary impacts. During the foilowing year of "low ecolorical stress" atier the shonage of rain, there was a decrease in tuberculosis monalitv rates. measured as an abrupt. temporary change (O = - 1.54. 6 = Y O) .bother period O t' high ecolooical stress that produced a measurable. temporary impact on overall tuberculosis monality was the choiera epidemic of 188 5. foiiowing another smallpox epidemic in 1 883-81 The estimated values were O = .99.6 = 40 These estimates were significant ar {pK 5 Most of the impact was on female pulmonary tuberculosis rnonalir.; rates (LI= I 5 4. 6 = 4 1. p< 05) This impact is consistent with that dunng the c holerd epidernic of 1 S6i. t\ hen r'emale pulmonary cuberculosis mortdi' rates rose from 2.6 prr thousand to ;u per rhousand. and overall female tuberculosis monality rates rose from -3 2 per thousand to 7 pzr thousand The cholera epldrmiç. 11 hich broke out in Aupst of 1885 and laaed milOctober of rhat year. caused onlt 22 si\ilian draths .Althourh nowhere near the scak of the 1865 rpidemic thar kiiled 3i,people. the cumulative etfects of penods of high stress nevenheless \vas kit Peaks of choiera ha\t been correlated with peaks in tuberculosis monality (Hardy 19% 2201 The generai cieath raie rose from 18 per thousand in the previous vear to 26 per thousand This \{,as a tinir of treniendous hardship in Gibraltar. and a larse portion of the population came to be dependeni on ulfare relief from charitable organisations. Dunng this period 4.03s people acceptcd dail\-relief Trade for supplies was also difficult. as the Spanish authorities ciosed the border ben\ een Gibraltar and Spain. The lack of suitable Bye-Law regarding removal of infected cases to Hospital. also would have plaved a role in maintaini- hiyh infection and monalitv rates. Compulsory removal to hospitai of infected cases came into effect ody in 1883 (Macpherson 1894). These Bve-Law were not very effective. as they couid only be enforced in the case of intécted persons occupying tenements for which the rent did not exceed ten pesetas weekly c SlacPherson 1894). This amount was later raised to 25 and 50 pesetas monthlv in 1889. Given the exceedingly hirh rates of rental in Gibraltar. this Bye-Law would have had very little effect Furthemore. there was no specific Bye-Law concerning the removal of t ubercular victims. The last srnailpos epidernic in Gibraltar occurred in 1894, and during that year the Medical Oficer of Health ( SlacPherson 1894) also reponed a measles epidemic. as well as a higliest monalit?. from cnteric fever since 1891 (41 per thousand). These adverse conditions also created a tluctuation in female tubercuiosis monality rates. raising the level t O t hree per thousand that \+rar This was measured as a temporary effect (t, = 1 38.8 = 30. p. 051 The end of the nineteenth centun rnarked the end of the years of "crisis years" of rptdemics in Gibraltar The analysis showed that several peaks of epidemic disease could precipitate an increase in tuberculosis mortaliry A similar reiationship berween peaks of tuberculosis monality and epidemics was seen in the case of London in the 1860s. when the cit!. Ir as unusually riddltd by epidemic disease (Hardy 1993 270). The post- 1900 decline staned when the tum of the century brought about events that sausrd chancies- in the profile of tuberculosis monality in Gibraltar. There was a crusade againsr tuberculosis in England. and manv administrative measures were instinited to reduce the risk of infection. and to isolate and care for infected persons. These measures started to receive serious consideration in Gibraltar. Athough tuberculosis mondity rates continued to be hi& 1903 saw the beCangof another deciine @= 0.861, pc -05). This was measured as an abrupt. permanent impact. Everi with the poa- 1900 decline in tuberculosis rates, conditions that encouraged hi@ tuberculosis rnortalitv were ail1 prevalent . Declining economic conditions. and the outbreak of World War 1 in 19 14. which funher exacerbated these conditions. coincided with slight increases and fluctuation in tuberculosis monality rates. Raised tuberculosis mortaiity in London had also been associated with social and economic distress (Hardy 1 993 231 ). .h abrupt. temporary impact was measured in 1918 when social and economic conditions grew increasingly worse There was also an influenza pandemic that vear. In .\ugüst of 18 19. there was a srrike by Spanish coalheavers (Colonial Repon 19 18). and the -neneral trade of Gibraltar was hampered considerabiy disrupted by the World War 1. These stressiùl tirnes were marked by a temporary increase in female tuberculosis monality (O = 1 OS. 6 = 58. pi O5 The impact of female pulmonq tuberculosis monalitv was t, = 33, d = 60. ( p.: 05) The larse values of 6 show that the effects of the impact of 19 18 carried over to the nest year The last period of decline îs marked by the evacuation of the civilian population in 19-39. as World War II besan in Europe. A permanent. abnipt impact was registered on the tuberculosis monality rate of males (O=-1 10. p< 05) Male pulmonary tuberculosis rates ( = 1 18. pi05) were the most strongly affected The results show that male tuberculosis monalitv rates fell belou. one per thousand der repatnation. Female monality rates did not resister a similar impact. .An examination of the monaiity rates showed that tuberculosis mortaiity rates had begun ro deciine sooner in females than in males. Their rates had declined to below one per thousand earlier in 1932. The results of the intempted ARIMA analysis confirm that the decline of tuberculosis monality in Gibraltar can be measured in three broad periods: 1) a period of decline from the hgh monality in the 1 860s. extending through 1878. This was marked bv a permanent, abrupt chanse in the mean level of monality rates. This decline was foilowed by a period of fluctuations in the monality rates. marked by a series of abrupt. temporary changes. which lasted until the turn of the centurv; 2) post-1900 decline and fluctuation. marked by a permanent change in the rnean level of tuberculosis mortality and a senes abrupt. temporary changes: and 3) post- 1939 decline. marked by the evacuation of civilians that year. The results also show thar while females show lower rates of tuberculosis mortaiity, their tuberculosis rates were more sensitive to changes in the environment than the males. 5.4 The Analysis of Aga-and-Sex Specific Mortality Rates Using Life- Table Techniques. The nem step of t he analvsis was to determine how the ag-structure of the population of Gibraltar contribured to the patterns of tuberculosis monaliry deciine described previously. This was achieved by using the age-and-sex specific mortalitv rates with Me-table techniques Fira. the overall life expectancies and probabilities of dvin- from al1 causes were established for males and females. Second. the probabilities of dying from tuberculosis were derived by applvins the age-specific monality rates for tuberculosis to the probabilities of d?ing tiom dl causes Thrd. havins established both sets of probabilities of dvins the impact of tuberculosis on life expectancy at binh was assessed by calculating the potential years of life that would be gained if tuberculosis were removed as a cause of death. Since the age-and-sex specific analvsis only extended to 1939. the chanses in the probabilities of dying and life expectancies will be discussed within the context of the first two periods of decline of tuberculosis mortaiity eaablished in the previous section. The first penod encompasses the decline from the high monality in the 1860s. eaending thou& 1878. followed by a period of fluctuations in the mortality rates until the tum of the century. This period will be collectively called the "pre-1900" decline. The second period was the post- 1900 decline and fluctuation, which lasted until the 1939 evacuation of the civilian population of Gibraltar. 5.4.1 Lifc-Expectancy and iMot-tality Differentials by Age and Sex Life expectancy at binh values for the pre-and pon 1900 periods. computed fiom the ordin. ay life-tables usi ng the age-specific monality rates show that the life expeaancy of both males and females increased from the nineteenth to the twentieth centuries. From the 1860s to the 1930s. the lire espectancy for males increased from 3 1.32 at binh to 47.78. The life rspectancy at binh for fernales increased from 39.17 to 55 99 54.2 Age-Specific Probabilities of Dying from All Causes .A cornpanson of the are-spectfic probabilities of dying from al1 causes (Figures 20a gf 20b) before and after 1900 shows that in males and females, a substantiat contribution to the life expectancy ditrerence came from a decrease in mortality in the under 1 and 1 to 5 age tnren-als In the males. and to a iesser exrent in the females. the nsks of dying increased in the older ases (60 and above, The difference between the male and female patterns is that a larger part of the improvement in iife expectancy in males from the nineteenth to the twentieth centun occurred throueh the diminution of monality in the adults (25 to 30. 30 to 3 5. 3 5 to 40. and 40 to 47). but this was balanceci by an increase in monaiity at the older ages in the males afler 1900 Figure 20s: Probability of Dyng From All Causes. Males Age inteml Figure 20b: Proeability of Dying From Al1 Causes. Females 5.4.3 Male Age-Specific Probabilities of Dying from Tuberculosis: Prt1900 Fisure 7 1a shon 5 r he age-specific probabilities of dying ftom tuberculosis for males in the pre- 1900 period The patiem of tuberculosis mortditv in males shows four definite . peaks The firsr peak occurs aiter the first vear of life, in the one to five years aoe interval. The second occurs in Young adults (25-30),the third in ages 35 to 40. and the fourth in the 60 to 63 age interval There is an apparent peak at the 75 to 80 age intervals, but the probabilities above age 70 should be interpreted with caution. due to the small sample sizes ai this age range In males. the nsk of dying From tuberculosis is hiehest at ases 3 5 to 40. tollou rd by 75 10 30. 41 1 IO 45 and 45 to 50 in al1 three periods around the censuses. The probabilir ies are highesr cir t hr bcsinning of the study penod in the 1 860s. and decrease in subsrquent decades Tiic probability of duin5 fiorn tuberculosis in the 25 to 30 age internai showed a larger drcrew t hrough rime. compared to the 3 5 to 40 ase interval 5.4.4 Male Age-Specific Probabilities of Dying from Tuberculosis: Post-1900 .aer IOOU. ihr agr pattern ot'tuberculosis monalitv in males shitied (Figure 21a). The highest risk of dimg fiom rubercuiosis atier 1900 was concentrated in the oider age groups The peak rit 3925 1 to = almost disappears. The are pattern changed from one with four peaks in the prr- IL~f~~)period. to one trith a slisht peak at ages 25 to 30 and the larges peak at ages 60 to 65 5.5.5 Female Age-Specific Proba bilities of Dying frorn Tuberculosis: Pre-1900 Figure 3 1 b sho~sthe age-specific probabilities of dying from tuberculosis for females for the pre-1900 penod During this period. the highea probabiiities of dying from Figure tla: Male Probabilies of Dyng From Tuberculosis Figure Zlb: Femaie Probabiltties of Dymg Frorn Tuberculosis 45 t tuberculosis were concentrated in the 20 to 25 year age imeival. There are three other peaks, in the 35 to 10. 70 to 75. and 75 to 80 age intemals. As in the male probabilities. the peaks atier 70 years of age are interpreted with caution. given the small sample site in these ages. The peak in the 1 to 5 ase interval is much smaller than in males. 5.5.6 Female Age-Specific Probabilities of Dying from Tuberculosis: Post- 1900 The probability of dyins from tuberculosis for femaies decreased dramatically afier 1900 (Fisure 71b). Overall. the pattern is the same as in the pre-1900 period. but much depressed There is no obvious shifi of higher probabilities to the older age categories. except that the highest probability of dving from tuberculosis shifled to the 25 to 30 are interval. and t here is a slight increase in the probability of dying at the 60 to 65 aee interval. 5.6 Impact of Tuberculosis on Life Expectancy: Cause Deleted Life Table Analysis Table 1: Cause Deleted Life-Table Analysis. Tuberculosis Removed. Gibraltar f I I PRE-1.300 1 POST-1900' il Males Females Males Females il i Life Esprcrancy at Binh 3 1 .32 3 9.3O 47.78 55.99 I 5' I i !/ Years of Life Added if Tuberculosis 1 4 j? 1j - 3.64 ) 3 37 29.35 N'ere Rernoved i I I 1 1 1 I "kir" Life Expectanc?. 1 35 61 1294 1 50.15 58.34 lt 1 1 1 -Percentage Gain 1 12.4ooo 8.48 % 1 4 73 ?/O 4.03 % 1 1 Data on dl-cause monality was available only until 1939 '~alculatedas a percentage of the years of lire added divided by the "new" life e~pectancy Table 1 shows the potentiai gain in life expectancy if tuberculosis was removed as a cause of monalitv. calculated as a percentage of the "new" life expectancy at binh. The results show that the impact of tuberculosis on life expectancy diminished through time for both males and females. In the pre- 1900 period. the potential gain in life expectancy at binh for males was 12 10 percent. from 3 1 22 to 3 5.64. Mer 1900. the potential gain for males was onlv 4 73 percent. brinsing the life expectancy up from 47.78 to 50.15 years. For females. the percentage potential gain in life expectancy in the individual penods was less thari in males In the pre- 1900 penod, the gain in life expectancy for females was S 18 percent Life espectancy at binh that would result from the removal of tuberculosis increased from 39 30 to 55 99 vears. 5.6. I Cornparison between Male and Female Differentials Overail. the risks of dying from tubercuiosis in Gibraltar dufin the period of study ikere hi-her for males than fernales Both the males and females show changes in the age pattern of the probabilit! of dying from the nineteenth to the twentieth century. The probabilities of dyng trom tuberculosis for both sexes decreased through timr The results of rhis anaivsis show that there is a strong correlation between life ctspectancy and agr-speci tic tu berculosis monality . The probabilitv of dying from tuberculosis decreascd as life especrancy increased. In the males (and to a much srnaller ctsrent in females 1. as liir espectanc!. increased the hisher nsk of dying fiom tuberculosis shiiied to the older age groups Puranen ( 199 1 : 105) observed that in males. particularly in tows. tuberc~iosisis concentrated in the upper ase goups. The results are consistent with Hemno and Sawchuk ( 1984. who showed that reproductive and post-reproductive males experienced a significantly higher monality rate from tuberculosis than did females in Gibraltar Newsholme ( 1906b) noted that the historical decline oftuberculosis in Enpland and Wales had been much greater among women than among men and that the age distribution of deaths fiom phthisis had shified to older age groups. A similar parteni was noted in Paris (Preston and van de Walle 1978) This nse in tuberculosis monality in the older age groups has been interpreted as the ebb of an epidemic with a long periodicity. spread through increasine exposure by se-ments of the population. and ultimately diminished by genetic selection (Grigg 1958) Hemng ( l98ï:zS) suggested that the shifl of tuberculosis rnortality to the clder ages in Gibraltar retlects this late phase of tuberculosis epidemics. The length of the st~dyperiod. however. is roo short to confirm or disprove the occurrence of an epidemic u ave However. if tuberculosis rnonality in Gibraltar was part of a large epidemic wave. then the decline of tuberculosis monality during the studv period may represent waves of much lorver amplitude. N hich are a result of localised. short-tem changes. such as changes in sanirat ion The Bos-Jen kins analys sugsests rhat the occurrence of short-term tluctuations during the study period. rather than an immunolo@cal chanse. was responsible for the decline of tuberculosis monaiir! in Gibraltar .uother interpretation of this pattern of increased tuberculosis monah!. in the older a-es ma! be found in the cohon effect. Children between the ases of five and titieen appear to be more resistant to tuberculosis (Dubos and Dubos 1957) This is retlected in the probabilities of dyine for both sexes. However. although children aged five to tiîieen rarely died from tuberculosis. they were aill at risk for exposure, and ma' in part account for some of the progessive tuberculosis cases later in life. CHAPTER 6 THE DECLINE OF TUBERCULOSIS iN GIBRALTAR: AN INTERPRETATION The time-series analvsis of tuberculosis monality in Gibraltar From 1860 to 1967 showed that in a period of over one hundred years tuberculosis mortalitv rares declined from over 5 per t housand to less than I per thousand annually. in a series of decline and fluctuation cpisodes The decline of tuberculosis monality in Gibraltar can be observed in three broad periods I the pre- 1900 period of decline and fluctuation; 2) post- 1900 to 1939 deciine and tluctuation. and 3 1 the post- 1 93 9 decime. marked by the evacuation of civilians that va. The lack of a detenninistic trend in the iuberculosis monalitv rates of Gibraltar suggests rhat tuberculosis was not declining on its own accord. and that the explanations for its decline niust be sought in the conrext of the overall monality regime and its immediate environmental îontest. Preston and van de Walle ( 1978) also sought an explanation for the maintenance of hi~hruberculosis rates in r he immediate epidemiological environment. notably in the quality or' the Liater supply and sewagc disposai. Although the connection rnight nor be intuitivelv ciear. ii is reasonable ro infer that monalitv from airbome diseases. including tuberculosis. are intluenced bu water quality and quantity (Preston and van de Walle 1978). The importance orkater-borne diseasrs is show by the overall age-specific probabilities of dving, where a mbsrantial contribution to the life rxpectancv difference from the nineteenrh to the twentieth century came from an improvernent in the very Young ases. This is congruent with the monality e'rpenence of populations experiencing high monality fiom water-borne diseases i Preston and van de Walle 1 978 ) The many episodes of diarrhoea that result from sontaminated warer deplete and weaken the host and result increased susceptibility to infection fiom airborne diseases. The results of the intempted ARMA confirm that there is a significant correlation berween episodes of epidemics water-borne diseases such as cholera and increased tuberculosis mortality. Hardy ( 199321 1 ) pointed out that this relationship can be obscured by the problem of duration, as an increase in tuberculosis mortalitv. precipitated bv an episode of cholera could take beween two to four years to reach termination. The correlation between cholera and tuberculosis peaks may also be affeaed by local social and economic circumstances of the overall monaiity situation. Nevenheless. the results in Gibraltar suppons the contention (Hardy 1993: Preston and van de Walle 1978) that epidemics of choiera. whether directiy or as an indication of prevailing sanitary conditions. mav be correlated with increased tuberculosis monality. Given the predorninance of water-borne diseases in infiuencing the monality profile of Gibraltar. especiallv before 1900. the decline of tuberculosis monality must be examined in the contea of the overall monalip decline. The decline in tuberculosis monality before 1900 in Gibraltar was ciosely associated with the overall monality decline. as show by the cross- correlation analvsis The rnonality regime in the pre- 1900 period in Gibraltar was one of hi@ back-round monality Tavlor et al. ( 1998) demonstrated a similar association between tuberculosis monality and the overall monality deciine in 19th century Australia. Szereter ( 1988) suggeaed that sarut- refonn that arose in response to infectious diseases causing the high background monality was significant in reducing tuberculosis levels in England. Afier 1900. when the rnonality regime in Gibraltar changed to one of low background rnonaiity no si~nificantcorrelation was found between the patterns of overail monality decline and tuberculosis monality decline In addition to seneral sanitary measures against disease, specific measures against tuberculosis were introduced dunng this period. The cross-correlation analysis between overaii moriaiity and niberculosis in the pre- and-post 1900 periods indicates that the causes of decline of tuberculosis monality in both periods must be considered separately. The lack of a significant correlation betwem tuberculosis mortalitv and overall rnortality patterns suggest that. during this period, some of the factors responsible for the decline of tuberculosis rnonality were diRerent fiom those before 1900. The cause-deleted life-table analysis shows that the impact of tubercuiosis on life expectancy was clearly different before and after 1900. In the pre- 1900 period, the potential sain in life expectancy at binh for maies was 12.10 percent. while after 1900, the potential gain for males was only 4.73 percent. For fernales. the percentage potential gain in life expectancy decreased tiom 8 48 percent before 1900 to 4.03 percent after 1900. The decrease in the impact of tuberculosis on life expectancy afier 1900 in Gibraltar also suggeas that additional factors were operating to reduce tuberculosis monalitv in the twentieth century By examinino the conditions that influenced overail mortality and tuberculosis rnonalitv within both periods in Gibraltar. the direct and indirect factors associated with the decline of tuberculosis mortality may be svnthesised. In this chapter. the decline of tuberdosis monality in Gibraltar as show by the previous analvsis. ivill be discussed in two pans: pre-and-post-1900. The discussion is structured as hllow s for each period. the historical context of the overall monality regime is first described Second. the occurrence of tuberculosis monality within this context is discussed. and possible factors influencing the decline of tuberculosis are presented. 6.1 Pre4900: The Period of High Background Mortality in Gibraltar Since the establishment of Gibraltar as a British miiitary fomess in 1704, its epidemiolo@cal history has been one of a civilian population Living in the shadow of the constant threat of disease outbreak (Sawchuk 1992). Much of the epidemiological history of Gibraltar during the period of high background mortality was influenced by the behavior of classic sanitation and hygiene diseases. such as gastro-enteritis, cholera typhoid, and smallpox (Sawchuk 1993: 1996: 1997). The penod of high background monaiity in Gibraltar is defined as a period where chronic diarrhoeai diseases, together with other epidemics. caused monality rates to remain around or over 20 per thousand. Consequently. most of the efforts in the improvement of public health before 1900 were directed at eradicating these diseases. In addition to the sanitation and hygiene diseases. two diseases that were important in shaping the mondity profile of Gibraltar in the 19~cenniry were tuberculosis and respirdtory infections. sucn as bronchitis and pneumonia. The period of hish background monality was characterised by inadequate water supply. lack of a proper sanitation svstem. chronic overcrowding. and lack of laws or regulations controllin2 the qualit- of potable water and food. Ali these problems were related to the poor iniiastmcrurc of Gibraltar. especially that of the city proper To facilitate the reader's understanding of the state of the monalitv regime at the beei~ingof the aody penod in 1 860. a brief description of the eariy development of Gibraltar is presented. This section illustrat es the most important elements affectin8 monaiity housine and the development of Gibraltar's health and sanitary infrastnicture (water supply and sewage). A discussion of the type and qualit! food is also included. to assess the role of nutrition in the synergistic interaction between the health and sanitary infrastructure. and monality. 6.1.2 Housing, Crowding, and the Spread of Oisease The social development of Gibraltar as a city was similar to that of a Victorian indusuial tom. except that in Gibraltar the weaithy lived in the sarne congsion and squalor as the poor. as there was no room to achieve any great degree of spatial separation (Harvey 1996). Sawchuk ( 1993) demonstrated quantitatively the negative impact of communal living on health. under conditions that tàcilitated the spread of disease. The characteristic unit of farnily residence in Gibrahar was thepano (Sawchuk 1993). .-\ centrai counyard (parro)served as a shared space around which apanments were built. These prios were often confined and ill-ventilated (Sayer 1862:477) The only access to ihese multi-level tenements was through a narrow passageway. In 1878. approximately t hree-quarters of the town inhabitants lived in buildings housing twenty people or more. The patios themselves were built close together, resulting in a network of small alleyays and passages This amansement of the houses and streets was simiiar to that of southern .-dalusia. but much more concentrated. The residential system stemmed from the scarcity of land suitable for construction of dwellin_es. and it entailed communal living including shanng essential resources such as the water supply and laundry facilities. Each patio was essenridlv a self-contained community where women. the elderly, and children spent most of their time .A salient feature of para living. and of most housin8 in Gibraltar. is that most dwellings were rented. rather than owned by their inhabitants. This opened the system to abuse. and in the absence of rent control and the chronic shortase of accommodations. tenants were ofen at the mercy of landlords (Sawchuk 1993: 880). The lack of ownership also resulted in a perception of the duality of "public" and "pnvate" space. with irnponant epiderniolo~cal- consequences (Sawchuk 1993: 881 ). The "private" space. which refend to the inside of the dwellings were likelv to be kept as clean as possible by the residents. However. the "public" space. which included the common courtyard. shared entrance, well and potable water supply and communal laundry areas were not maintained. because these areas were seen as the responsibility of the landlord. The unsanitary conditions included defects in house drains. badly plad water-closets which were not rnaintained, unpaved yards and passages. darnp walls and floors. and lack of proper ventilation (~ollï'ns1890). Houses had no means of central heatinp, or proper cooking facilities. Consequently. when people resoned to buming wood and charcoal in these quaners, conditions becarne even more intolerable. Taken as a whole. the deplorable conditions of housing and the lack of space in Gibraltar made overcrowding an important factor in rnaintaining the high background monalitv Underlyingj the problems of housing conditions and overcrowding during the study periods was the health and sanitary infrastructure upon which these houses were built. 6.A .3 Development of Gibraltar's Health and Sanitary Infrastructure To understand the development of the state of sanitary conditions at the beginning of the studv period in 1860. it is necessary to examine the conditions that gave nse to Gibraltar's health and sanitary infrastructure. With most of its inhabitants crowded into a town of less than four km'. the Administration of Gibraltar fought a constant battle to keep population levels. sanita? conditions. and disease at a manageable level. When General George Don assumed the duties of Lieutenant Govemor of Gibraltar in October 18 14, he came to be in chaoe of a citv that had been hastilv rebuilt afier the Great Siege of 1779-83 The rebuilding followed the old Moorish plan which was based on the housing and sanitary needs of a much smaller popuiation ( Sawchuk 1993 :879). To rectifi this unsuitable inFrastructure, George Don introduced radical transformations in terms of building, institutions. and sanitary works ( Sawchuk 1993 :79). A Sanitary Commission was created in 18 15 to take charge of these works. His civil administration was important in the development of Gibraltar because it attempted to deal with the problems of epidemics. over-crowding, and improving relations with the Spanish governrnent (Kenyon 19 1 1; Dennis 1WO:36). Any improvemenr in sanitary conditions, however. was offset ahr George Don's death. In 1848, Sir Roben Gardiner replaced George Don as the Governor of Gibraltar. He did not agree with the administrative style of Generd Don, and wanted to administer Gibraltar as a fonress (Demis 1 990 :3 6). Since the prirnary sigiuficance of Gibraltar was as a strategic military fonress. social and matenal development of the civiiian cornmunity was of secondary importance to the Colonial govenunent during his administration. The goveming of the population in this marner reflects Gibraltar's colonial history and role as a gamson town, where control of political and social policies lay in the hands of outsiders (Sawchuk 1993878) The infiasrructure started by General Georse Don lay in stagnation. Conditions deteriorated. and overall backeround monality was high: The hi& rate ofmonalitv mono the population suggests either local causes of disease or unhealthy atrnosphenc influences. The situation of the tom and the almost total absence of sanitary precautions undoubtedly tend to raise the death rate. ln ma- houses cesspools or accumulations of night soil exist, which. throush the apathy of the habitants and the disregard for stench and filth. remain untouched for years. slow. srnoulderinp hot-beds of disease." (Sayer 1862: 474175) In the f 860s. when Captain Sayer made those observations. there was no Public Health Act in the Colonies Sanitary practices were unreplated. and the administrative machine? to deal directly wi~hproblems caused by the squalor did not exist. At the hem of the sanitary problems in Gibraltar were lack of a proper water supply, an inadequate sewage systern. temble housing conditions. and lack of amenities and sanitary precautions. 6.1.4 lnadequate Water Supply and the Sewage System The lack of a proper water supply was the moa senous limitation to the heaith and sanitation of Gibraltar. There is no surface water, and until the desalination plants of the 20th century the main source of drinking water was rainfd which was coilected fkom roofs on dwellings, and stored in underground tanks. Dependence on rainfall lefi the inhabitants of Gibraltar constantly vulnerable to water shortage, especially in the hot summer months. Droughts were a serious threat. and a period of high ecologicai stress could directly or indirectly affect the monality profüe (Sawchuk 1993:88 1). Furthemore, water coUected fiom the roofiops ofien was contarninated, as no precautions were taken to filter the water before it entered the storage tanks. The roofs of the houses were often used for washing, and hanging clothes. and keeping poultry. so that water collecteci Eorn this source was more often t han not impure (Sawchuk 1 993 :88 1 ). Even this unsatisfactory source of dnnking water was not available to dl. as many dweilinçs lacked private storage tanks, particularly in the poorer districts in the upper pan of the Rock. The other main source of water was fiom public and pnvate wells (Finiayson 1994:63 ) Water could ais0 be purchased. usuaily 6om Spanish day-laborers who distributed the water in kess or barrels. In the dry surnrner months, the scarcity of water made this an expensive source. This primitive system of water supply was also susceptible to contamination. Gibraltar's Sanit- Commissioners had no effective control over the cleanliness or handling of the water receptacles until specific bye-laws were introduced in the 20" century ( Sawchuk 1 993 : 88 1j *'The means of distribution . . . leave much to be desired; in fact there is constant danger of the water being fouled after it leaves the Commissioners' dimibuting stations ...by the more or less careless manner in which it is conveyed by the A Parliarnentary Commission on "Barracks and Hospital Improvement on the Sanitary Conditions and Improvement of Mediterranean Stations" (Governent of Gibraltar1863) provides an illustration of the water supply of Gibraltar at the time: a) Fountain at the center of town or fiom North Front supplied 179 houses (2775 persans)- 1 .5 gallons/head/day; b) Wells of bad or brackish water for 133 houses (2320 persans)- 1 gallon 1head/day ; C) Cistems for 136 houses (4497 persans)- 1.5 gallons/head/day, and; d) ten wine houses and tavems with brackish water wells- yielding 4 gallons each daily. In the report. the Garrison Quanemaster stated that "the inhabitants (of Gibraltar) owe nothing to the British Government for the srnail ~pplyof water they have had for 150 yars" (Government of Gibraltar 1863). The only water pipe in the whole Town was an old Spanish aqueduct built in 1571 In addition to an inadequate potable water supply. there was lack of water for sanitation purposes. Sewaee disposa1 was correspondingly inadequate. There were no comprehensive plans for a complete system of drainage, dthough facilities existed for the construction of one (Saver 1862474). There were main sewers that emptied into the sui at vanous places dong the line-wall, but which were useless in the dry surnrner months. During these months. waste material collected in the drains and some leached into the porous rock to contaminate nearby wells. Stokes (1867) descnbed the "fou1 state of the waters in ( ditches)." Even when flushed out by raidi sewage continued to be a problem. The main sewage outfd was located at the southem tip of the promontory and a linle to the Mediterranean side. where eddies around the rock occasionally carried some back into the Harbour (Stewart 1967). The poor sewage conditions persisted throughout the 1800s. The Medical Report of 1884 (Government of Gibraltar 1884) described the "unhealthy conditions of toilets and sewage disposal" and of "leaking of sewage pipes down to the pavement" causing "fevers." The lack of an adequate supply of clean dnnkmg water and a proper sewage disposal system had a senous impact of the overail mortality profile of Gibraltar. Water supply and sewage illustrate the complex relationship between social and physical variables. In areas where sanitary conditions, as well as avaiiabüity or access of potable water, is largely dependent on administrative policies. health and water qwhy are closely correiated (Goubert 1988: 179; Sawchuk et al. 1985). 6.1.5 Type and Quality of Food during the Period of High Background Mortality The Gibraltarian diet has been described as the "Mediterranean type". largely grain- based. with a minimal amount of meat (Erskine 1998: 14). One of the earliea reports on the diet of the civilian population of Gibraltar came fiom Hemen (1830:78). who desaibed a diet of "fish. especially salted and dried. pork in its fresh and salted state, macaroni. rice, oil, bread. and a large proponion of legurninous and other vegetables." He~en'sdescription showed that food choices were also influenced by the British garrison's taste for bread and sait pork. As there is no arable land in Gibraltar, the population was largely dependent on food brought in from Spain or Morocco (Sawchuk 1993: 890). The pnmary means of distribution of food in Gibraltar was through food vendors in retail stores, or sueet vendors. As in the case of the water suppiy. without regdations and the personnel to enforce them, food was ofien contarninated (Sawchuk 1997). Stokes (1867) reported the public sale of unsound food, such as "condemned pork darnased hits. putrid and ronen fish. unwholesome sausage. rnildewed cheese, (and) bad flour." Occasionally. food declared comaminated by the authorities was later reintroduced in a clandestine manner into the tom for consumption among the poor (Sawchuk 1997). This sorry state of flairs persisteci into the 1890s. Macpherson ( 189 1 :21 ) reponed that "1 7 carcasses of diseased pigs, 24 of diseased bullocks. 2 of diseased sheep, and several quantities of fish and vegetable. in various stages of decomposition. were brought to Market during the year.. ." Bread. the staple food item of the poor, was ofien contaminated by the "filthy and disgracefùl state of the licensed bakenes" (Stokes 1867).Medical Reports in the 1890s cite the use of sanitary (non-potable. or brackish) water and the use of mules in the kneading of the dough as a major contributin- factor in the poor sanitary state of flairs in Gibraltar's bakeries. The use of sanitary water in the summer months in the making of bread was also reponed. this led not only to intestinal distress but aiso to an increased susceptibility to choIera (Sawchuk 1997) Concem about the contamination of the milk supply also featured prorninently in the Medical Reports. About 7 1 percent of the total rnilk supply of Gibraltar in 189 1 came from Spain with no sanitan control (Macpherson 189 1 :21). Macpherson described two kinds of milk sold in Gibraltar lrchr pro. or "pure" milk and leche con agrra, which frequently contained up to 60 percent of added water from surface wells in nearby La Linea. The rate of contamination was hia. In 1892. 1 1 out of 15 milk sarnples tested at random fiom meet vendors fiom Spain were found to be contaminated (Macpherson 1892: 12). Milk was nored and boiled in dim rooms and patios, and near water closets (Macpherson 1893 : 13). 6.1.6 Tuberculosis in the Period of High Background Mortality It was in the poor sanitary conditions described above that tuberculosis in Gibraltar existed in the 1800s. To put into context the magnitude of tuberculosis mortaiity in Gibraltar in the 1800s. the overall monaiity rate from tuberculosis in Gibraltar and various co~es and cities from 188 1-85 are presented in Table 2. The figures show that the tubercdosis monality rare was comparable to those of the cities expenencing increasing industrialisation. The dinerence in the rates reflects in part the different stages of urbanisation and its attendant problems. In Paris, for example, the high rate of tuberculosis was linked to the trend ofoveraii monality caused by variation in the local sanitary environment (Preston and van de Walle Table 2: Cornparison of the Tuberculosis Mortality Rates from Gibraltar and Selected Countries and Cities, 1881-85 MORTALITY RATE FROM TUBERCULOSIS PER 1000 (1 88 1-85)' Gibraltar 3.23 1 England and Wales 1 1.83 R London 1 II t II Scotland l 2.1 1 II II Ireland I 2.08 Il / Massachusetts 3.14 I Pans 4.4 1 Berlin 3.32 1 7 - Y 'all figures except for Gibraltar are from Newsholme (1906b) The cause-deleted life-table analysis showed that the impact of tuberculosis in Gibraltar was highest before 1900. which correspondeci with the period of high background monality. The highest rates of tuberculosis modty were associated with the eariy period of high background monality. and interrupted ARIMA analysis suggests that the waxing and waning of epidernic and endemic irdectious disaises during episodes of "crisis mortality" were responsible for some of the fluctuations in tuberculosis mortality rates. The results of the .ARMA andysis show that short-tenn processes Wenced pdmonary tuberculosis modty rates. Although the conditions predisposing a person to infection or re-infection rnay be long- term. the factors hastening death corn active infection may operate relatively quickly. Some of these factors may have been found in the same conditions that perpetuated the hi@ background rnortality . The Medical Report of 1884 (Govenunent of Gibraltar 1884) aated that after the epidemic diseases. the most significant cause of death was "consumption". which accounted for as much as a third of overall monaiity. In 1884, tubercuiosis was considered an endemic disease in Gibraltar. It was recognised that in addition to the water-borne diseases of cholera and typhoid. tuberculosis was also intimatel-, comected to sanitary conditions. The report -Goes on to lis five causes of consumption that were directly related to "sanitary administration" 1 dampness in homes and dormitories: 2. an excessive stillness and absence of ventilation; 3 absence of means to heat home in winter; 4. the lack of cooking faciiities and consequently inadequate sleeping and living space; and 5 impure air due to the excess of carbonic acid _pas resultins from buming carbon in quaners improper for this. Throughout the 1800s. poor living conditions continued to be intirnately comeaed to consumption. or phthisis: ". . . we have, according to nearly unanhous opinion, to assign the firn place to the bad domestic hygiene, to the influence of continuous residence in crowded living rooms. tainted with orgnic and inorganic exuviae. ill- ventilated and damp...it wodd be hard to fhd any factor in the production of phthisis, which can daim more importance than that." 6.1.7 Factors lnfluencing the Decline of Tuberculosis during the Period of High Background Mortality Although before 1900 there were no specinc measures by the Govemment to deal with the treatment and isolation of tuberculosis cases, the general measures instituted in response to the high overall mondity fiom the epidemics could aiso have had an effect on reducing the tuberculosis monality rate. This is supponed by earlier analysis of the overall probability of dying which showed an improvement fiom the eighteenth to the nineteenth century in adults Eom 75 to II. who were at highest nsk from tuberculosis pnor to 1900. The significant correlation between overall monality and tuberculosis monality decline before 1900 shows thar the sanita. measures taken in response to the epidemic and infectious disease could also have had an efect in reducing tuberculosis monaiity. Szereter (1988) had arged t hat improved sanitation water supply. and ot her public health measures t hat reduced monality in England could have had a secondary efTect on the decline of tuberculosis. The combination of poor housing. overcrowding, lack of a proper potable water supply. and the poor sewage disposa1 system maintained high background monality in Gibraltar From gastrointestinal diseases, punctuated ôy epidernics of measles, cholera, and smallpox throughout the 1800s. The devastating series of epidernics evennially forced the Colonial Govemment to take measures to mitigate the effects of the unhealthy environment. .b a response to the cholera epidemic of 1865, a Board of Sanitaq Commissioners was re- established, and expanded (Sawchuk 1993:881). This Commission was in charge of roads, lighting. and sanitation. as well as enforcing proper sanitary measures in dwellings and provisions of water supply The new Commission was the fim nanitory body ganting powers and duries to Gibraltarians (Demis 1990: 38). The Sanitary Commissioners remained in force until a City Council was set up in 192 1. In 1869. the £irst Public Health Ordinance made it mandatory for a11 new dweilings to have underground tanks (Finlayson 1994). Even with the public waterworks in the 1860s- however, the only water for houses in the upper part of the Rock stiii had to be carried up by donkeys, and was very expensive. The wateworks, purnpins up water from undesround sources, brought water only to central points; neveriheless. improvemenis continued to be made. The course of sanitary. and later. housing refom in other European cities tended to foiiow a similar pattern to t hat in Eneland. ait hou@ the timing of the reforms varied with the timing of urban growth (Burnett 199 1 : 175). in England the "Great Clean üp" stand fiom the 1880s: man? enclosed couns were opened up. %ack-to-back" houses were convened into "through" houses. water closets replaced cesspools and earth middens. and piped water was laid on to individual houses ( Bumea 1 99 1 : 1 75). Progress was slow. and many En@ish towns did not acquire proper Lrarer supplies and sewage systerns until the 1890s; and in many cases on& as a response to risln3 rates of disease (Bumett 199 1 : 175). Gibraltar followed a simiiar pattern of sanitation changes. although sisnificant changes in housing were considerably slower and much more dificuit to achieve than in England. Work cornrnenced on the construction of a sewage svstem in 1868. Even so. sewage and main drainase were not instdled until the 1890s Nevenheless. these efforts seem to have been panially successful in reducing the generai monality rate; by the 1890s, the overd rnortality rate had dropped from 3 5 per thousand in 1860 to beiow 20 per thousand. Hardy (1993) suggested that some of the preventive measures in response ro these infectious diseases might have been covertly directed against tuberculosis as well. The emphasis placed on the adequate ventilation, concem about sewer-gases, and overcrowding could have been partlv motivated by the desire to reduce mortality fiom tuberculosis. Although there is no evidence to niggest that this rnight have been the case in Gibraltar, there are indications that the Medical Ofncen were aware that th& Hom at improving the general sanitary and li* conditions did coincide with a decrease in tuberculosis deaths (Macpherson 1891. 1892). The discovery of the tubercle bacillus by Roben Koch in 1882 was an important impetus for the new anti-tuberculosis movement in Bntain (Bryder 1988:16). in England and Wales compulso~notification had been introduced to enable health authonties to appiy prevent ive measures to stop the spread of uifection. to keep track of cases. and to ensure that each case was able to iake advantage of facilities avaiiable under the tuberculosis scheme ( MacNalty 1 93 2 :3 ) B y 1 890. however. "general medical consensus" in Gibraltar was still not unanimous on the issue of tuberculosis as a notifiable disease (Collins 1890). Xe~enheless.iMedical Officers of Gibraltar recognised the importance of prevention and detection: thev advocated measures such as bactenological diagnosis for early deteaion of tuberculosis. and uged that medicai practitioners advise patients as to the dangers of spitting and insist on the use of separate utensils (MacPherson 1891). They also knew the importance of isolating the infected. and in ail fatal cases. a thorough disinfecting of the prernises of the deceased (Macpherson 189 1). In 1895, notification was made compulsory for infectious diseases such as measles and smailpox. That same year an Ordimince was passed requishg school authorities, parents. and guardians ensure that children in a family where there was any infectious disease not attend school untd the Health OBCicer certified that the risk of infection had disappeared. Tuberculosis was aiU not made notifiable as of the 1890s. However. the introduction of notification permitted house inspections and gave medicai authorities limited powers to remove uifected penons to hospiral. Inadveitentiy some cases of tuberculosis may have been discovered in this manner. The role of diet in the deçline of tuberculosis during the period of high background monality is difncult to assess. However, the fiequent contamination of food and milk supplies in rhe poor sanitary environment must have been pady responsible for poor nutritional stanis, which in turn would be expressed as a greater susceptibility to infectious disease. including tuberculosis (Lunn 199 1 : 136). The high risk of oastrointestinal diseases during the penod of hi& background monalitv ensured that food contamination further predisposed a person to ruberculosis through weakening tiom bouts of severe diarrhoea. There was no regulation of food or milk quaiity throushout most of the nineteenth century. Bye-laws concemino the inspection of food and milk supplies by medical authorities came into effect at the end of 1893 (Macpherson 1893). Although it was difficult to regulate unsanitary practices such as the boiiing of mik in diny rooms. considerable reform was aimed at preventing milk shops fîom usine water from surface wells. sunk in the neighbourhood of drains (Macpherson 1893: 14). Supervision over bakeries. food. and milk supplies was maintained. 6.2 Post-1900: The Movement to Low Background Mortality in Gibraltar Bv the tum of the century. the regime of high background mortaiity had given way to a monality resime with a lower ievel of background mortaiity. By this time, the episodes of "aisis mortaiïty" had passed, and the overall rnorrality regime was largely free of epidemics causing high mortality. Important improvements to the infrastructure had been made by this rime, including the improvement to the sewage system that had been completed in 1899. In 1903. huge carchment areas for collecting and storuig rainwater were completed (Rose and Rosenbaum 199 1 :82). Despite improvements, problems aernming fiom poor sanitation and inadequate water suppiy persisted, dong with one important factor in maintaining infectious diseases that remained constant from the previous century: overcrowding. 6.2.1 Overcrowding and Living Conditions The Annual Repon of Health of 1900 cited overcrowding and mode of life as the most important factors in maintainhg a high mortaiity rate kom infèctious disease in Gibraltar (Elkington 1900). "The great difficulty in Gibraltar is to provide adequate isolation from infectious diseases in tenement houses, aiready overcrowded and with no spare room to devote to sick persons" (Annual Repon of Health 1908). In England. "overcrowding" was defined by statute in Engiand in 189 1 as more than two adults per room. not including sculleries and bathrooms (Bumett 199 1 : 168). The extent of the problem in Gibraltar was such that as late as 1937. there were "families living in stores with no natural light or ventilation and with no access to sanitary convenience Save by meam ofa public highway, and no drainage" (Mansell 1937) The common factor that afTected every measure taken to reduce tuberculosis monality in Gibraltar from the beginning to the end of the study period is the endemic crowding and poor housing conditions that had become an accepted part of life in that city The inherent defects of construction, and the crowding of people on a d area, made it dificult to actueve sanitary ïmprovements. The "back-to-back syaem of construction and overbuilding of sites in the poorer areas were the two main eds of housing in Gibraltar (Dansey-Browning 1916). "Back-to-back" houses shed a cornmon back and side wall with its neighbours (Burnett 199 1 : 163). According to the 1920 Annual Report of Health (Parkinson 1920). a majority of tuberculosis cases occurred in the "back-to-back" houses. "Back-to-backs" had been prohibited in Manchester. England. since 1844 (Burnett 199 1 : 174). The workmo classes iived under conditions of overcrowding which would have been ccnsidered intoierable elsewhere in Europe. with the Colony almost 20% in excess of its nomal capacity (Mansell 193 7). 6.2.2 Type and Quality of Food during the Period of Low Background Mortality The composition of the Gibraltarian diet afier 1900 appeared to have changed linle from the previous ceniun The diet remained the "Mediterranean type," which was largely vrgetarian with small quantities of rneat (Erskine 1998). Meat was considered a luxury, as it was reiativelv expensive. 3s were egs. milk and cheese. Cooking was done with a low quality olive oil; fish was ofien fned in oil with garlic and onions. The most important elements of the Gibraltarian diet in the eariy 1900s were potatoes and bread because of their low cos ( Sawchuk 1997). Of the rotal caloric intake, bread was the most important source followed by margarine. butter and cooking oils and sugr. Meat and fish oniy contributed 7.8 percent of the total number of calories ingested (Sawchuk 1997). Ln the summer hits and vegetables were obtained fiom Spain. This iargely vegetarian diet was more due to economics than choice, and remaineci unchanged untii der World War II (Erskine 1998: 18). A report on the cost of living for the "working class" fdy(defined as a man, wif'e, and three cMdren on a weekiy budget of fifty shillings) reveded that the food budget covered only the staples. with no allowance for extra food (ManseU 1939). Contamination of food continued to be a health probiem during the period of low background monality. Mules continued to be used to knead dough for bread in the eariy 20' century (Sawchuk 1997). The hua1Report of Health of 1926 reported some improvanent in the retail shops, such as protection fiom fies and dut, but there continued to be probiais with the quality of milk. Street vendors, and the sanitary condition of meat supply and public markets ( Srnates 1926:gO) The use of human and animal waste as fertiliser contributed to the contamination of hits and vegetables irnported from Spain (Erskine 1998:18). 6.2.3 Tuberculosis in Gibraltar after 1900 .4s Europe entered the twentieth century. there seemed to be renewed interest in the fi@ aeainst tuberculosis. in Endand, an extensive anti-tuberculosis campaig was launched (Bryder 1988: 2). Newsholrne ( 19O6b) attributed the deciine of tuberculosis in England to the increasing segregation of consumptive patients. While there were no syoematic steps to isolate consumptive patients in sanatona in Gibraltar, increasing measures to detect and rernove cases to hospital were implemented. The death records at this time show an increasing nurnber of tuberculosis deaths in hospital. Before 1900, 5.6 per cent of tubercuiosis deaths occurred in hospital. Mer 1 900. this figure rose to 1 1 per cent. In Gibraltar afier 1900. the impact of tuberculosis on life expectancy diminished. althou@ it remained an important cause of death. Table 3 shows the magnitude of the tuberculosis mortality rate in Gibraltar around the tum of the cenw relative to selected countries and cities. The relative improvement in Gibraltar fkom the previous century is comparable to that of the other cities, with the exception of Ireland and Norway, where there was no unprovement. Table 3: Cornparison of the Tuberculosis Mortaiity Rates from Gibraltar and Selected Countries and Cities, 1901-03 MORTALITY RGTE FROM l TUBERCULOSIS PER 1O00 Gibraltar I 2.07 England and Wales I 1.23 London 1.65 Scotland 1.47 lreland 2.15 Norway I Massachusetts I 1.67 Paris 1 3.65 Berlin I 2.04 'al1 figures except for Gibraltar are from Newsholme (1906b) 6.2.4 Factors lnfluencing the Decline of Tuberculosis during the Period of Low Background Mortality The Annual Health Report of 1903 summarîsed the extent to which measures against tuberculosis that were in effect in England were canied out in Gibraltar around the tum of the century : 1. Bacteriological diagosis-The examination of sputum was regularly performed in the Sanitary Commissioner's Laboratory. 2. Notification of cases voluntary or obligatory-Tubdosis was not yet on the lia of noiinable diseases in Gibraltar, but the Medical Officer arongly recommended this legisiation (Tuberculosis was not made notsable mil i 906). 3. Law againa public spitting- this law was enacted in England, but not in Gibraltar (In 1904 there would be a General Notice against spitting in public places, but an actuai Bye-Law was not enforced). 4. Disinfection and cleaniiness-There was as yet no systematic measures for Sanitary inspeaors to disinfect the roorns occupied by tubercular victirns (when reported), or at theof death. 5. Sanatoria-The Medical Officer of Heaith urged the administration to provide facilities for training of staff and for isolation and treaunent, but this was not easy to achieve in Gibraltar was space was severely lirnited. 6. House-to-house inspections- this continued to be done. Again, changes were proposed, foilowing the standards set in England. It was proposed to amend the Be-Laws based on those suggested by the London County Council. to require that drains and fittings require be brought up to the standards of those in large towns in England. 7 General sanita? improvement- one of the most imponant obstacles to reducing infectious disease in Gibraltar continued to be overcrowding. These measures may be discussed in four broad categories: notification and detection, TB Schemes and the isolation of infecteci persons, increasing awareness of preventive measures through education. and generai sanitary improvement, which involved dealing with housing and the overcrowding described previously. 6.2.5 Tuberculosis Notification 8 Detection Gibraltar's Medical Officers were stiii fiinctioning with limited powers at the tum of the cenhiry. They felt that ". . .it would be advisable to adopt a synem of voluntary notification of these (tuberculosis)cases, to enable the Sanitary Officiais to visit the houses, and to give advice regarding precautions to be observed to prevent the spread of infection" (Elkington 190 1). On June 23.1906, the Sanitary Order Amendment making tuberculosis a notifiable disease was instituted. The two main objectives to notitication were removal of acute cases from crowded dwellings, and education on preventive measures. Under this Amendment, sanitary officiais visited cases notified and explained preventive measures. A card explainhg preventive measures was left with the patient. In the fim year of notification, most patients objected to the disinfecting of their rooms, but by the next year most people consented to have their roorns disinfecteci (Horrocks 1907). AU notifications of tubaculosis were strictlv confidentid. Ln 1907 was a legislation passed (Health Ordinance of Infectious Diseases (Notification) Acts ) to enable Medical Officers to remove cases of infectious disease to the appropriate hospitais. Despite compulsory notification. the Medical Officer's powers were ail1 limited. Cipon notification. the medical pranitioner was contacted and asked if he wished the victim's farniiv or house visited bv the Medicd Officer of Health or Sanitary Inspecton or whether he preferred to cany out anv necessary measures himself (Fowler 1910). The infected were ailowed to remain in their houses. There was no systernatic means of tracking people afready under treatment. Therefore, multiple notification was possible, where the same cases were reponed twice or more as different cases. At the same time, there was still relu~cein the population to report cases of tuberculosis. By 19 13, seventy per cent of the 500 tuberculosis cases that had ben reported had died (Fowler 19 13). The high mortality rates of tubercuiosis indicate that cases of this disease were seldom reponed until they reached advanceci stages. There was a long-standing stigma against tuberculosis. Nearly a century ago, in a statement read to the Govemor in 1822, the Surgeon of the Civil Hospital reported that: ". . .the Spaniards and other Foreignen believe this disorder to be Ulfectious, and generally refuse to receive into their dwehgs so afüicted; and the fiiends and relatives urge their admission into the Hospital with a view of relieving themselves fiorn the burden and expense attendant on the last stages of an incurable malady " (Barker 1822) Most notifications occurred only when the patients were approaching the period of disablement from work or in need or rnonetary or other relief (Dansey-Browning 1916). By this time, there would already have been ample opponunity for contact and spread of infection. Other indications of the reluctance to identiQ one or to be identified as tubercular based on financial reasons may be found in the retums of notifications by occupations. In 19 14. for exampie. housewives accounted for 46 percent of the cases, with the nea highest category being the unemployed (27 percent) foiiowed by waiters (1 5 percent). Surpnsingly, coalheavers and tobacco choppers ody accounted for 12 percent of the notified cases ( Dansey-Browning 19 14) These proportions were common in the yearly retums of notifications. The high percentase of housewives and unemployed may be related in part to their increased exponire to infection at home. However, the lower percemage of notifications in higher nsk occupations such as coalheavers and tobacco choppers indicate that many were probably reluctant to corne forward for fear of losing their liveiihood. 6.2.6 Post-Notification: Medical Onicers and Further Measures against Tuberculosis The Amniai Report of Health of 1909 included an abstract of the mernorandun by Dr. Arthur Newshoime on administrative measures that couid be taken against tuberdosis (Fowler 1909). The abstract outlined the recommended measures such as education, eady diagnosis, a tuberculosis dispensary, and sanatorium treamient. However. despite their awareness of the deep-rooted problem, the official position of the Colonial Govemment seemed hopeless. There is some evidence to suggest that other infectious diseases were still considered more important than tuberculosis: "It appears strange that this disease should be aliowed to daim 25 victims during the year with little or no comment, whereas had these patients been struck down by small-po~every effort would have been put fonh to Save them. Consider for a moment the position of these victims of consumption: the years of sdering; the struggie to eam a livelüiwd and continue work; the paupensing result; the spread of infection to others; the endless chah of misery which consurnption can and does cause. ..what in Giiraltar had been or is being done.. .? What has been arrangeci for the victims of tuberculosis? Cm we answer that anything at ail has been done for hem? .. Sufferers in the last stage of consumption and in destitute circumstances have been allowed to die. where they might happen to find a last resting place, spreading their infection broadcast, because there has been no place in the colony which would receive them." (Fowier 190917) In desperation, the Medical Officer appealed to the pragrnatic concems of the Colonial "There are very cogent reasons from a financial point of view, why the disease should be stamped out.. .Its presence arnonga a population means that deterioration in that race of people is infallibly taking place. The starnina of the race is sapped. not only by the ravages of the disease, but by the breedhg of idenor offspring, and as a consequence of the working capacity, and therefore, the fuiancial value of its labour mua depreciate. These facts are often los sight of by the Authorities, when fàced with what they may consider the unremunerative outlay of public money for administrative measures to combat the disease." (Fowler 19 10) The Colonial Goverment reacted slowiy to the tubercuiosis problem. By 1910, the only administrative outcome of the recommendations of the Medical Ofncers had been the compulsory notification of tuberculosis in 1906. The seeming reluctance of the Colonial Government to take immediate steps to combat tuberdosis was surpriiing, given the national carnpaign in England, and perhaps reflected Englaad's attiîude towards the "Colonies". Further exchange between the Medical Officer of Health and the Colonial Govenunent resulted in a Cornmittee was appointed by the Govenunent to deal with prevention of the spread of tuberculosis in 191 1. The persistence of the Medical Officers and the Sanitary Commissioners even~dywould lead to tbe estabiishment of tuberculosis schemes. and effons by to isolate infected cases and providing relief for the victims' families continued by the establishment of tuberculosis "Homes." 6.2.7 TB Schernes, Sanatoria and Isolation of lnfected Persons The problems concemîng the removal and isolation of tuberculosis victirns were of weat concem to the Medical Officers. Two ways by which tuberculosis monaiity might be C reduced are bv: 1) a decline in the nurnber of infeaed persons; 2) a reduction in the nurnber of infected persons who develop the disease (Wilson 1990:368). The first measure characterises much of the effons to conuol niberculosis in Gibraltar, as there were no means to effectivelv treat tuberculosis before the advent of chemotherapy in the late 1940s, and chemoprophylaxis in the early 1960s (Cornstock 1986:2). Most of the direct counter- measures against the spread of tuberculosis in Gibraltar, therefore, involved attempts at the removal and isolation of infected persons. Soon after tubercdosis was made notifiable in 1906, the question of providing a sanatorium for consumptives in Gibraltar was considerd (Parkinson 1919). Dr. Arthur Newshohe, who was at the time considered the highea authonty on the adminimative control of tuberdosis in the Local Govemment Board Report, stréssed educational measures, such as teaching hygiene in school as an aid in the fight against tuberculosis. Recognising that "institution or domestic isolation of patients during the whole course of the disease is of course impracticablq" he recommaided "ternporary abode in a sanatorium" as being most effective (Annual Report of Health 1908). Unfortunately, the recommendation to build a sanatorium was not taken up in Gibraltar was not one that could be easily taken up in Gibraitar. The general conception of the ideal location of sanatoria in England emphasised the connection to local climatic conditions. In the early 19' century, it was thought that the wmclimate south of Europe was ideal for consumptives (Biyder 1988:46). By the rnid-19P century. preference for sanatona had switched to the Swiss Aips. Although by the 20~ century British tuberculosis specialists thought that the advantages of special climates were grearly exaggerated. local climatic conditions became a factor in deciding on the location of a sanatorium. A rural. open air senhg was preferred. Prevailing public attitude to tuberculosis and institutions for its treatment was also important in deciding the location of sanatona. ideally far away from centres of population (Bryder 1988:49). Both of these factors played a part in the Colonial Government's reluctance to build a sanatorium in Gibraltar. as it was impossible to meet either etenon. Financial considerations were also cited (Horrocks 1907). Therefore. as late as 1908. there was no place to care for consumptive patients in the late stases of their illness Even at Colonial Hospital. there was a lack of facilities to house dying vicrims of tuberculosis. In July 1908. the Medical Officer of Heaith asked permission ro admit to Colonial Hospiral a destitute woman who was in the late stages of tuberculosis and who was shanng the same bed as her son. The request was denied because it was an "unsuitable" case (Parkinson 19 19) This response was characteristic of an attitude that had been prevalent in the nineteenth century hospitals. Tuberculosis was considered a chronic "incurable" disease. and doctors were more interested in acute "curable'* illnesses (Bryder 88 241 .A hnher letter ro the Sanitary Commissioners raised the question of what might be donr :Or destitute consumptives as to their needs and upkeep. as well as their isolation from ot hrrs This led to a seriea of Ion- correspondence between the Sanitary Commissioners and the Colonial Government I Parkinson 19 19) When the matter was fhally put before the Governor in 19 10. the local doctors (Parkinson 19 19 provided a sumrnary of the situation: I Tuberculosis L\ as \ Cr. prcvalent. 2 The number oi'peopir jutfering from tuberculosis was not adequately represented bv the returns. and 3 The recorded monalii!. multiplied by 15 would -ive a more correct figure. 4 .A '-place" ousht to be provided for the reception and treatment of tubercular cases. lt is significani rhar the term -'tuberculosis" was le% out on purpose in the naming of the iaciliiy ro care for consumptives. possibly to overcome the sti-ma that prevented victims from reponing tuberculosis at earlier stages There was ". . .an extraordina- sti-ma attached to (theJ \\ord tubercuiar in Gibraitar the mere proxirnity of a so-called tubercular person is to be avoided. and the poor patient is looked upon as son of pariah (Fowler 191 2: 10). 6.2.8 The Tuberculosis Scheme and the Sanitary Cornmissioners' Home In 19 1 1. a Commission was appointed by the Govemor to detemne the ement to which tuberculosis had increased found that the number of cases of tuberculosis dunng the period of 1906 to 19 10 was lower compared to the period of 189 1 to I89I. Thev ded that a sanatorium was unnecessary. recommending instead that a Dispensary be staned. for instruction and treatment of al1 stages of tuberculosis. The main function of the dispensary was diagnosis and health education. although tuberculin treatment was avaiiable. The dispensaq and relief measures were collectively known as the "Tuberculosis Scheme" There was to be a nurse in attendance and to visit patients in their homes. Some rooms in the poorer pan of town were closed down afier being considered unfit for human habitation .A Relief fund was recommended. A sum of 625 pounds for 1912 was to be administered bv the Sanitary Comrnissioners. Out of this sum provision is made for a doctor, a nurse. the carrying-on of a dispensary. the provision of certain food. and the allotment of extra rooms for consumptive patients Relief was given in the fom of milk and meat tickets, extra food. gants towards rents. ciothes. and medicine. The dutv of the doctor was to be tùlfillrd bv the Medical Officer of Health. responsible for the whole administration. Even with these measures. there was still the question of housing the tubercuiar patients In 19 1 2. the Sanitary Commissioners took matters into their own hands They renred a house and became "landlords" themselves. A house capable of housing ten families Lias found at No 57 Flat Bastion Road "for the accommodation of persons suffenng fiom advanced tubercuiosis and iheir families" (Parkinson 19 19). This place was officidly called the "Sanitary Comrnissioners' Home," .\ ponion of the house was set apart for temporary housin- of destitute persons suffering fiom other than tuberculosis who could not be accommodated in other charitable institutions. These patients were kept separate from tuberculosis patients and costs were met out of the "Destinite and Sick Fund" Relief was divided into "Indoor" and "Outdoor" Relief Outdoor Relief was moaly given in the form of milk and mat. and Indoor Relief referred to the stay at the Home. To de@ some of the costs. the majority of the patients were asked to pay a nominal rent on admission in proportion to the accommodations provided and according to how much they could afford to pav Rent was decreased with the diminution of their eaming capacities. and monetary assistance was given for food If there was no breadwimer the whole cost of maintenance was borne bv the fùnd .rlmost immediately, seven tenements were filled. Any patient applving for examination was accepted. but the treatment of the wealthy was not undertaken rxcept at the request of their usual medical advisors. In addition to the Tuberculosis Scheme. additional chantabie foundations were set up in response to meet the needs of the poor This period saw the establishment of charitable organisations such as the Child Welfare Centre. where milk and other supplies were distnbuted free or at low cost to nursins mothers. By the l!XOs. specific programs for the poor were instituted. such as the Food Supply Cornmittee that ran breadline and food subsidies. 6.2.9 Effectiveness of the Tuberculosis Scherne Hemng (1987.38) noted that Gibraltar's Tuberculosis Scheme was judged to be palliative on-. and less successfùl at directly attacking tuberculosis. There were some official objections to the scheme. stating that it would be impossible to induce patients to attend the dispensq. that patients would resent being visited at home, or that patients would not enter a "Tuberculosis" home Indeed. the Home had corne to be known as "Casa de los Tuberculosos" To counter these objections. the authorities tried to carry out the scheme as unofficially as possible (Fowier 1 9 12). Hardy ( 1983) suggested that prevailing conventions and rnythology of tubercuiosis obstructed concems of Medical Officers of Health about tuberculosis The Sanitan Commissioners' Home. or "Tuberculosis Home" was not a place of treatment for tuberculosis: it was merely intended to provide better housing for poor people suffenng from tuberculosis. specificallv to admit those people in advanced stages for purposes of segr 1909 Jn aierage of 52 sarnples of sputum were examined for tuberculosis annuailv. but by 19 10 to 191 3. this number increased to 171 (Fowler 1913). In 1919. the Sanitary Commissioners acquired a second house in Flat Bastion Road adjoining the first one This made it possible to separate tuberculosis patients from those destitute from other causes. In 1 92 1. the name of the Home \ras changeci to as the "Gibraltar Home for the Sick and Aged" ( Parkinson 192 1 1 In 1332. there were 5 1 men and 23 women inmates. In 1933, when the majoritv of the inmates wre the aged and infirm: the number of tuberculosis victims seeking admission was very Iimited There were aiso difficulties in trying to accommodate both tubercular and non-tubercular patients ( Jarneson 1933) Overall. the success of the Tuberculosis Scherne was limited. Scarce resources caused the tuberculosis tùnd to be used for more than its intended purpose In 1919 the Medical officer of Health reponed that the "Destitute Sick and Tuberculosis Fund" was assisrin- between sevent! and eighty families each month. including the non-sick or tuberculous. with food tickets for over 1.O00 pounds of beef and 2,000 pints of milk (Parkinson 19 19). The arongea indictment of the Tubercuiosis Scheme and the lack of funds appropriated to it came tiom the Senior Medical Officer ln 1936: "For twenty years I have referred to the absurdity of havins a Tuberculosis home without nursing, and the consequent necessity to house the acute. and. therefore. h@y infective cases in the Colonial Hospital. For much more than twenty vears the Colony has saved money over its negiect of tuberculosis. and now. 1 hope that it is eoing to disgorge its accumulated sum." (Lochhead 19 19) As an attempt at more direct means of dealing with tuberculosis. in 1936 an additional medical officer was appointed to the Colonial Hospital, with special expenence in the treatment of t he disease (ManseIl 1 936). An outpatient chic for consultation treatment, and advice was opened in 1937 The outpatient clinic was deemed successiùl. with encouraging attendance of the weekly sessions. The results attained "...even in so short a time have contimed the belief that sufierers are becoming increasingly willing and anxious to seek t reatment advice" ( Mansel1 1 937 9 1 6.2.1 0 Education: lncreasing Awareness of Preventive Measures The Sanitary Cornmissioners made every effort to educate the patients as to the causes of tuberculosis. and measures of prevention. "Until the people are educated to appreciate the full value of fresh air and sunlight. one can hope for little improvement" MacPherson !895 Cpon notification or advice of the patient's medical advisor the patient's home was visited. and a report made to the Medicai Officer noting mode of life of the family. and their financial and sanitary conditions. Patients were urged to sleep alone and dispose of sputum properlv. and use separate utensils (Frontispiece). Farnily members who were iii were urged- to -eet medical attention. and were asked to attend the dispensary if they could aord to do so. In 1908 the first of a series of Hem lectures, the "Causes and Prevention of Tuberculosis" was given. It was reponedly well-attended (Fowler 1909) Less popular was the enforcement of spitting bye-law (Smales 1922). 6.2.1 1 The Continuing Problerns of Overcrowding Attempts to irnprove the infrastructure of Gibraltar had started as a reaction to the epidernics of the previous century. However. eradication or even reduction of crowding was no easy task. as it would have been impossible to house any persons dispiaced by a reconstruction scheme of an? magnitude. There were expansion programs involving the dockyards and associated breakwater constniction works, beginning around 1880. and berween 1894 and 1903. but reclamation projects involving residential housing was not carried out until recent times (Rose and Rosenbaum 199 1 ;79). The Sanita.Commissioners feit that despite palliative measures. tuberculosis would never seriousiy be reduced until housing conditions in Gibraltar were considerabiy improved. In the previous century. the Medical Officer of Health had reponed in 1878 that: -'lt is now enerally admitted that overcrowding in close damp rooms is a most fenile source of pulmonary consumption.. . very frequently a whole familv of ten persons may be found sleeping in one close damp room, with windows and door closed and an oil or petroleum lamp buniing on the table." (Stokes 1878) 1 t was found that nead! al1 cases of tubercuiosis occupied old damp one-room tenements that \r.ere defect ively iighted and ventiiated (Macpherson 1 893). A tenement house or building is one that has been subdivided into separately-let floors. or single rooms (Bumett 1991: 162). "it is no uncomrnon thing to find a father or mother. suffering from "consumption". living in a single room with one or two children" (Honocks 1904). Even in 19 14. fi@-seven percent of notified cases reponed were eom one-room tenements (Dansey-Browning 19 14). Table 4 shows the mean number of persons in each type of apartment in Gibraltar. Table 4: Mean Number of Pe~onsin Different Types of Apartments, Based on Censuses YEAR 1 ROOM 2ROOMS 3 ROOMS 4ROOMS 189 1 3. IO 4.27 5 .O8 5.59 1901 3 61 4.85 5 .34 5.76 i 1911 2.57 4.31 5 .O0 5.34 2.47 4.04 4.35 5.40 1931 2.58 3.81 4.50 5 .O2 Perpetuating the seventy of crowding was the profit that was to be found in exploithg the desperate need for accommodations. Rising rents resulted in the subletting of rooms originally intended to forrn pan of separate Bats. In some cases these subiets were collectively known as "lodging-houses." ostensiblv intended to be used as temporary accommodation. but in reality housing the near-deninite who could ail1 afTord to pay the rent ( Burnett 1 99 1 : 1 62) Conditions were also made worse. when people were forced to use, as dwellings. stmctures that were totally unsuited for that purpose. The 1937 Annual Repon of Health provided examples of the temble consequences of overcrowding: a farnily of eight living on the nainvay of a tenement buildins; two families living in stable-nalls still containing horses. and families living in stores with no natural li_eht or ventilation and with no access to sanitary convenience save bv means of a public highway, and no drainage (Mansell 1937). Another consequence of the hi# rents was that it hindered removal of the sick to hospital. Cases of infectious diseases were dealt with bv removal to the Hospital. or by isolation in their own homes. The Sanitary Commission however, could only order compulsory removal hospital when the case occurred in a tenement paying a rent not exceeding fifiy pesetas monthlv This bye-law. first enacted in 1883. permitted compulsory removal of patients occupving tenements only if they paid rent not exceedine ten pesetas weekly (Macpherson 1894.10) Even afier this sum was amended to 50 pesetas monthly in 1 889. risine rems rendered it ineffective. Of great importance in controlling tuberculosis was the pro1 mged isolation of advanced cases. Although housing conditions rendered isolation at hoine impossible. victims of tuberculosis were often unwillino to leave their home. As rents cont inurd to increase. even those unwillino to leave their homes were forced to seek alternative housing The hieh rents and cost of livino in Gibraltar caused many Gibraltanans to seek ternporary residence across the border to La Linea. One unique aspect of Gibraltar is its relationship wit h the border town of La Linea. less than a mile away. Rights of residence in Gibraltar was severel? restricted and closely defined by the British, yet Gibraltar was dependent on the 10.000 workers who entered her daily from Spain. When relations were friendly \rith Spain. Gibraltar wage earners were allowed to travel fieely between La Linea and Gibraltar daily Their artachment to Gibraltar was strong, however, and manv came back to Gibraltar at eve? oppommity. "The love of the Gibraltarian for his home. and for dwelling in the City to which he belon_ps. is well known: if he can find place and opponunity to satis- this desire he will arain every nerve to do so" (Mansell 1937). There was little opponunity to ease the congestion of Gibraltar; any space vacated was promptly filled. For example. between the end of 19 13 and 19 16 there was a decrease of 354 aliens. This was irnrnediately balanceci by an increase of 352 British subjects. These British subjects were mainlv natives of Gibraltar temporady resident in La Linea who sought to take advantase of the empioyment and accommodations vacated by these aliens (Dansey- Brownine 19 17) Ironically. the need for rnonetary relief may also have brought manv native Gibraltarian tubercular victirns back to Gibraltar. Tuberculosis monality rares from 1909 to 19 18 showed that the marked irnprovement that coincided with bener housing in the last decade had not been maintained. The increase in monaiity rates may have been partially due to victims of advanced tuberculosis who retumed to Gibraltar from La Linea to seek assistance under the tubercuiosis relief scheme. and eventually died (Dansey-Browning 1918) 6.2.12 Housing Reforms and the Decline of Tuberculosis in the 1900s The preceding sections outlined the housing problems in Gibraltar. which existed together with the inadequate warer supply and sewaee -stem. The contemporary accounrs by the Medical Onicers ideaified the heaith hazards arising from overcrowding. bad construction. and lack of ventilation. Together with the problems ansin5 from inward- looking patio svstem. hgh leveis of rem. unsatisfactory arrangements for cooking and storage of food. and other social probiems due to poor housing. conditions that encouraged the spread of close-contact diseases. inciuding tuberculosis. were prevalent. Ill-ventilation and '-impure air" were repeatedly cited by the Medical Officers as causes of pulmonary consumptïon These problems were exacerbated during the winter. The inward-looking pio culture made attempts at ameliorating the Qrcumstances difiïcult. Ventiiators (vents) instalied bv the Commissioners were blocked up by the tenants themselves, because they felt that the opening permined outsiders to look inside. or get into the room at night (Macpherson 1891: Fowler 19 12). Many of these roorns had only wooden shutters which when closed shut out al1 air (Fowler 19 12: 10). Furrhermore, the people themselves saw the source of infection as coming From outside. and believed that the only chance of protecting their children was to ciose al1 windows and doors (Horrocks 1904). .A very large proportion of cases of tuberculosis occurred in the upper part of the town. which contained the most crowded districts. These districts contained a very large number of one-room tenements and back-to-back rooms. and were chiefly inhabited by the poorer classes. The Medical Officers noted that certain houses in these districts annually sonribute their quota of tuberculosis cases in spite of the anempts to improve their sanitary ionditions (Fowler 19 12). Some of the most important measures againa infectious diseases, therefore. involved attacking the problem of crowding and removal of cases from within the tenements In 1903. an imponant milestone concerning rernoval of cases of infectious diseases to hospital was the decision of the Supreme Court on the question of Common Lodung Houses. It was decided that cornmon occupation of a room by members ofdifferent families was to constitute a "common lodguig house*' This meant.that lodgings and tenement houses couid now be also included as Cornmon Lodoing Houses. This mling in turn necessitated a reconstruction of the Sanirary Order and the Sanitary Commissioners to require Lodeings and Tenement Houses be inciuded when makîng Bye-Laws for giving notices and takins precautions in cases of infectïous diseases. The previous law conceming the removal of infected cases to hospital had been based on the rental paid by the occupant of the tenement. which was not effective due to the abnormdy high and steadily rising rents. In this indirect rnanner. a major obstacle asainst spread of inféctious diseases including tuberailosis \vas removed. .Uthou& slow. improvements continued to be made. Fowler (1 9 12) noted that since 1902. many of the worst and most crowded tenements had been'ciosed. The Public Ordinance of 1907 contained sanitary provisions regarding sewage. water suppiy. and regularion of housing ( Smales 1 !Z6:9O). By 19 1 1. the percentage of families livino in one- room apartments had fallen from 36 percent in 1901 to !3 percent. In 191 1. a bye-law sonceming overcrowding was passed. This by-law was based on the recommendations of the Housing Committee "That. pari pussri wit h the removal of families from overcrowded premises. the accommodation vacated by them be earmarked by the Medical Officer of Health as fit for only a certain nurnber.. of persons. and that the owner of such premises be notified to the eftèct.. (Parkinson 1 92 1 ) This bve-lax \vas significant in that ir was to prevent landlords from causing a rrcurrence of the ouxcrowding by simplv acquiring new tenants Previously. no legslation rxisted to prevent overcrowded premises from which families have been removed to retum rd a simlar state Aso significant in 192 1 was a new method of dealing with buildins plans jubmtted for approval An' plans had to be evaluation by the city council now from a pure- janii* standpoint. afier \r hich the! were passed to colonial and military authorities for final approvai By 193 1. the nuniber of farniiies in one-room apanments had dropped below 10 percent Table i shows the percentage occupancy of the various types of dwellin_es,based on the number of rooms. t?om 189 1 to 192 1. The number of one-room dwefings decreased after 190 1. with the exception of 195 1. when crowdino increased again with the post-war boom in Gibraltar. Bv 1953. no extensive slums existed in Gibraltar. and new flats had been constructed Table 5 Percentape or Family Occupancy by Nurnber of Rooms. Based on Censuses / \EUX 1 ROOhl 1 2 ROOMS / 3 ROOMS 4 ROOMS 1891 i --7~ 3 33.78 25.29 15.55 j 1901 , 3600 69.51 1 1931 11 17 i 1911 1 13 87 3 5.44 3 1.49 19.30 / l l , 1921 i 1508 1 34.07 30.19 22.66 I 6.2.13 Evaluating the Impact of Post-1900 Changes on Tuberculosis Mortality Oecline in Gibraltar .-Uthough it is not possible to direct!. measure the specific influence of housiny itself in quantifiable rrrms. one could crnainiv argue that housine improvement and reduction of crotkding played a role in the decline of tuberculosis monality. especially after 1900. Dubos and Dubos recognisrd that Iivin~conditions si-nificantly affected the severity of a patient's response to tuberculosis i Dubos and Dubos 1987 19-3 One way to test this assenion is to examine t he pattern of ot hrr respiratory infections. such as bronchitis and pneumonia another sensitive indicator of general housing conditions. .As in tuberculosis. the infectious agents of these diseases are also spread throueh the air by droplets. and exhibit a high incidence in situations of intensive cro~vding(van Ginneken 1990:844). A cornparison between the pattern of overall tuberculosis rnonality deciine and the monality rate fiom other respiratory diseases (Figure 1 la. Chapter 5) shows that panicularly &er 1900. both diseases declined at similar rates. with the esception of the sudden increase during the 19 18 influenza pandemic. The similar pattern could be interpreted as significant indicator of the influence of improvements of housing on both causes of death. The Tuberculosis Scheme and Homes set up by the Sanita? Commissioners undoubtedly reduced infection by isolating some of the consumptives. but a larse pan of the improvement must be anributed to housine changes. If the Tuberculosis Sshemes and Homes played a larger role in the decline. the pattern of tuberculosis rnonality nould deviate fiom that of the respiratory infections. for the latter LL ould not br affected b!. the specific measures against tuberculosis. As a final test of the relarive influence of housing irnprovement and reduction in crowding on the monality rates of tuberculosis and other respiratop infections. a cause-deleted analvsis was camed out for ot her respiratory diseases Given the hypot hesis that both tuberculosis and ot her respiratory disrasès ikere declining riom housing irnprovements and a reduction of crowding, the introduction of an additional factor in reducins tuberculosis mortality. if substantiallv effective relative to housing. \rould br seen in the difference between the relative sains in the two causes of death Table o jhot~sthe resuits of the analysis. The results show that there was no substantial differencr in the relative percentage gain of tuberculosis and other respiratory diseases This supports the contention that improvements in housing and the reduction of croivding had an împonanr efect on the decline of tuberculosis monality in Gibraltar. relative tn orher factors operating at the same time .A more detailed examination of the relationship between housing and tuberculosis monality is needed. however. before more can be said about improvemenrs in housing. This analvsis is presented with the caveat that the only measure of improvement in housing avaiiable at the time of the studv \vas the level of crowding. Table 6: Cornparison of Relative Years of Life Gained from Removal of Respiratory Diseases to Tu berculosis. Pre-and-Post 1900. l PRE-1900 1 *POST- 1900 Il Males Fernaies 1 Fernales / 11 .- ii Liie Expectancy at Binh 1 33.28 39.8 48 56.7 l 1 ïrars of Life Gained if Respiratory 3.1 1 3.13 2.9 Disease Were Rernoved ,i i 11 -.Sew" Life ~s~ectancy' 36.39 42.93 Cl 51 59 6 : Percenrage Gain- i Ratio of Gain from Pre-to-Post 1900. I 0.79 : Respiraton Disease 1 Ratio of Gain tiom Pre-to-Post 1900 1 I ! Tu berculosis ' I the yean of life gained if respiratory disease were removed added to lire expectancy at birth . -the percentage of the "new" life expectancy to the "real" life expectancy at birth 'calculated previously ln addition to housing improvements and reduction of crowding. attempts at improving sanltary conditions continued afier 1900. with a successive series of bylaws regularin the w-ater. milk and food supply The hnual Reports of Health aîier 1900 show that these t hree areas. although improved Frorn the last century. continued ro be a problem in Gibraltar until Korld War 11 The specific effect of improvements in sanitation may be retlected in the lower background rnonaiity dunng this period. Aithough improvements in housing and reduction of crowding were largely responsible for the decline of tubercuiosis monality afker 1900. it is likely that the secondary effect of improvements in saniration on reducing tuberculosis monality continued to operate. The role of diet is more difficult to assess. As the composition of the diet remaùied fairly constant from the previous century until afier World War II. any effect of diet on the deciine of tuberculosis rnonality in Gibraltar during this penod is more likely to be due to a secondary effect of reduction of food contamination. 6.2.14 The Final Stage of the Decline in the Study Period: Post-World War II Measures Against Tuberculosis In 1937. constnic~ionbegan on the King George V Memorial Hospital for lung disease. for impatient treatment. not only of tubercuiosis, but also for other chronic and acute lung diseases. This was the tira sanatorium-type Fdcility for treating tuberculosis in Gibraltar, built bu funds raised t hrough public subscnption (Hemng l987:j8). Meanwhile. the renovations continued on the Gibraltar Home for the Sick and Aged Home, and a new Home wth an attached infirman. \vas proposed (Mansell 1938). The King Georse V Mernoriai Hospital was compieted in 1939. but was occupied by the militan during World War II. .Mer the war. the hospiral was finallv used for its intended purpose The stigma attached to the disease still linoered. and some resoned to seeking treatment elsewhere, outside of Gibraltar (Durante 195 1 ) Overall. however. by 1952 the number of deaths was the lowest since the repatriation of the civil population in 1945. Nthough overcrowding ni11 csisted. more people were seeking advice in the earlier stages, and with the extended use of antibiotics and chemoprophylactics. such as BCG. tuberculosis mortaiity decreased. Streptornvcin. the first effective anti-tuberculosis dmg. was discovered in 1943 (Bryder Even so. precautions continued to be taken. In 1953. a voluntary scheme to detect and minimise ideaion for empiovers was instituted. The govemment .provideci free facitities for x-ravs of prospective or alreadv ernployed domestic servants (Durante 1952). Many workers were reluctant to be screened. perhaps for fear of losing employment. The AMU~ Reports of Hedth through 196 1 show that the Scheme was much undenised. In 1964. a new .Ami-Tuberculosis Scheme \+as sraned to systematically check up on certain categories of workerc The foollowing categories of workers were periodicallv x-rayed I Ai new workers wishins to reside on Passpon 2. -41workers already residing in Gibraltar on Passpon 3 Public Transpon iborkers 4 School teachers 5 Hairdressers and barbers 0 Food handlers Jlaids and nannies immigration .-\uthoritlesgranted immi-rant workers a provisional permit of residence until the results of the radiological esamination by the medical oficer were known In 1965. al1 school entrants were tuberculin tested CHAPTER 7 CONCLUSIONS The process of decline of tuberculosis in Gibraltar From 1860 to 1967 was one in whch successive improvements in sanitation, housing, and preventive measures influenced year-to-vear levels of tuberculosis monality. The results of the MUMA modelling show that tuberculosis rnonality rates in Gibraltar could be modeîied with an autore_errssive parameter, indicating that the overail tuberculosis rnortality rate from one year was mon strongly affected bv the monality rate from the preceding year. The deciine of tuberculosis monaiity in Gibraltar was show to have occurred through a successive series of shon-term reductions in monalitv influenced by extemal factors. Dubos and Dubos ( 1987.705) maintained that -naIlopine consumprion iras probablv more the result of medical i~norancethan of high susceptihility to infection The results indicate that tuberculosis monality was brought about by conditions that increased the intensitv of contagion (exposure). and weakened the infected individuais. hastening rnonality The length of the study penod is too short to cofirm or disprove the occurrence of an epidemic wave. but the decline of tubercu~osismonality from 1860 to 1965 mav represent waves of much lower amplitude. which are a result of localised, shon-term chanses. such as changes in sanitation. Accordingly. exphnations for the decline of tuberculosis monality of Gibraltar were souat in its epidemiolo@cal. sanit-. housing and socio-medical histon Overall. the risks of dving from tuberculosis in Gibraltar during the period of studv were higher for males than fernales. Both the males and females show changes in age pattern of the probability of dying fiom the nineteenth to the twentieth century. The probabilities of dyins from tuberculosis for both sexes decreased thou& time. To retum to McKeown's central problem of ascnbing weights ro the individual component causes of the tuberculosis mortaiity decline. the analysis shows that while the mechanical process of the decline may be modelled effeaively. it is difficult to ascribe a numerical value to the individual causes described above. The interrupted ARb& however, provides a measure of the effects of certain events on mortality rates in panicular years. if interpreted in their panicular hisroncal context. The combination of time-senes analysis and life-table methods allowed for the charactensation of the diEerent periods of decline (pre-and- post 1900) Mer detineating the dflerent penods the decline of tuberculosis monality, it was possible to examine the possible causes for decline in the two periods. The main strategy in éstima~ingthe efectiveness of specific causes of the decline of tuberculosis in Gibraltar used in this studv was to detail the epidernioiogical. administrative and sanitary history of the city and to interpret the decline of tuberculosis in this context. .VcKeown ( 1976) had surmised that sanit. and public-health measures were efTective only against water-borne diseases afler the middle of the nineteenth century. However. it was shown in Gibraltar that sanitation and public-heaith improvements, even if indirectly. did have some effect on the reduction of tuberculosis monality. panicularly before 1900 Aithough there were no specitic measures by the Colonial Goverment to deal with the treatment and isolation of tuberculosis cases in Gibraltar. general sanitac improvement measures instituted in response to the high overall rnonalitv from the epidemics also had an effect on reducing the tuberculosis rnonality rates. Before 1900. the decline in tuberculosis monality was closely associated with the overall mortalin. decline. The highest rates of tuberculosis monaiity were associated with the early period of hi& background monaiity. and interrupted NUMA anaiysis niggests that the waxing and waning of epidemics during penods of "crisis mortality" and endemic infectious diseases were responsibie for some of the fluctuations in tuberculosis monality rates. .Mer 1900. improvement in housing and the reduction of crowding played a significant rote in the decline of tuberculosis In Gibraltar. The improvements gained bv the reneral sanitary measures before 1900 continued to operate. but the specific improvement in t housing conditions and reduction of crowding began to make their impact. The measures concerning housing reforms were effective at two levels: the first from direct reduction of crowding. and the second from measures faciiitating removal and isolation of tuberculosis \ictims. such as the bve-law redefining Common Lodging tfouses. In addition to this. direct measures ayînst tubercuiosis such as the TB Scheme and the Sanitaq Cornmissioners' Home also contributed to the decline of tuberculosis in Gibraltar. albeit in a limited fashion. Despite the limited success of the Tuberculosis Scheme. the efforts of the Medical Officers did increase detection. and provided housing for some of the advanced cases of tuberculosis. Puranen ( 199 1 ) showed thar exposure to tuberculosis was a consequence of liMn_e conditions, hygienic standards. as well as place of residence and the isolation of patienrs in sanatoria Ai1 of these factors. except the last one. operated in Gibraltar throughout the study penod. .Aller 1939. overall tuberculosis rates had begun to fa11 below one per thousand. .Uthough borld War II intempted this decline. it was clear that rates were falling steeply. The post-war period saw the use of mass radiosraphv and other schemes that facilitated the discovery and isolation of active cases. The King George V Mernorial Hospital for lung diseases was finail- used for irs intended purposes after repatriation. and undoubtedly had a sigiftcant effect on the reduction of tuberculosis monality through isolation of consumptive patients. Cenainly. when the King George V Memonal Hospital came into use afker World War II. along with chemoprophvlaxis. tuberculosis rnortality dropped greatly. The role of nutrition in the decline of tuberculosis monality in Gibraltar rernains to be fully established. The present study shows that it is likely that the contamination of food and mik. as well as the limired amount of food avaiiable due to its high cost added to the general il1 heaith and susceptibility to infectious diseases in both penods of high and low background monality The low qualitv and level contamination of food remained in place until chanses brought on by the evacuation of civilians and World War II. Until the 1960s. the composition of the Cribraitanan diet largeiy remained the "Mediterranean type". mostly vegetarian with small quantities of meat There was no major shifi in diet dunng the study period to indicate an irnprovement in nutritional status t hat would have a siqificanr impact of the decline of tuberculosis in Gibraltar This study concludes that it is not possible to ascribe any single cause as the sole factor eausin2 the decline of tuberculosis. and that the influence of different causes of tuberculosis monality decline operated tosether at varying levels of effectiveness. Although some factors ma! predomnate at different times during the course of the decline. as shown by the different character oithe deciine of tuberculosis in Gibraltar before and afier 1900. a monocausal expianation for the decline of tuberculosis could not sufficiently account for the complex interaction between the ditferent factors involved. Funher. it was shown that in the relative absence of specific measures against tuberculosis improved sanitation. water suppiy, and other public health measures that reduced overall monality in Gibraltar could have had a second- eflect on the decline of tuberculosis. Even McKeown. in his later work, concluded that the spread of tuberculosis was closely tied to poor hygienic conditions in association with water-and-food-borne intestinal diseases such as typhoid and dysentery (McKeown 198852) This study also demonstrated that housin3 was an important environmental factor influencing both overall monality and tuberculosis monality in Gibraltar. Additionaliy. where crowding was endemic as in Gibraltar, improvements in tuberculosis monality rates could be achieved by redefining non-physical aspects of housing. such as factors affecting rernoval of consumptive fiom the premises. a) Box-Jenkins anaivsis shows that the decline of tuberculosis monality in Gibraltar fiom 1860 to 1967 was predicated on shon-terni local conditions operating to influence yearly mortality rates. and that the decline was not due the natural cycle of the disease. Cross- correlation tiinct ions i ndicate that that the decline of tuberculosis mortality in Gibraltar was closely related to r he overall monality decline before 1900. but deviated afier 1900. The @h correlation between overall monality and tuberculosis monality before 1900 is due to the predorninance of water-borne disease during that period. which reduced resistance to tuberculosis Internipted ..IRIMA analysis indicates that the decline occurred in t hree episodes of declines and fluctuations. which cm be measured bv three permanent mean changes. one occurring atier 1875. during the period of high backeround mortality in Gibraltar. the second dunng the tum of the century around 1900. when Gibraltar experienced lower backgound monaiity. and the las occuning afler World War iI. Life- table techniques shou ed that the impact of tuberculosis of on life expectancv changed correspondinpl! before 1900 (high impact) and afker 1900 (lower impact). b) Examinarion of the historical circurnstances of the decline of tuberculosis rnortality in Gibraltar showed that before 1900. the decline of tuberculosis monalitv could be attributed to successive improvements in sanitation and water supply that reduced rnonalitv fiom water-borne diseases. although there were no direct efforts at reducing tuberculosis rnonalit~ .Ifter 1900. the predominant factors iduencing the decline in tuberculosis monality were improvements in housing and reduction of crowding Specific measures againa tuberculosis. such as the TB Scherne, experienced iimited success until afier WorId War II when treatment through chemoprophylaxis and isolation at the King George V Hospital was available. Figure la: AuWomb&m Fundioii of Mak tu^^ Mœtality Ratas Lac fzrr. -.-. ...... A.**- . :.OGO 194.9 2.000 ...... 243.- ,.CO@ f -.63' . .??: ...... 289." 2.000 ...... --.56: ...,, 37;.; :.C)O@ ...... 49i.l L.3CL' : -.;;: . .?li ...... 2.5 3.000 . - - - 2 . :?.;a ...... 447.; l~.aoo ...... 465.4 T.UiiG ...... - :-. * .2?- . ?a; k ...... - 14 *.251 ...- -4 r ...... et , ;7. -...... -- 9 -0- . -:5+5 k ...... I Figure Ib: Partial Autoconslaüon Function Male Tuberculosts MortalRy Rates Figure lc: Aut- Funcûon of Differenced Male Tuberculosa Mortalw Rates - ...... - . - . . --.- . .#.., ...- 4 il.:; . k-: I -. . - -- . - ,--- . .-- C - .... .j-4.- . -.-- A - . - - ..L ....-... . .,.. - - -- ..... -. ... .-_'Y . -, ...... ,.a ...... -= ,A. - . . -- . a-- - .. .;3:5 - - -.- ...... -- . .-. - .-.- ..C -c. .r ...... -- , - . . -- . - -- - .I.. ., ,-c.*: ** --.- Figure Id: Partial Autocorrelation Functron of DifferencedMale Tuberculosis Martality Rates Figure le: Autaixmclatm Function of Log-Transfomied and Oifferenced Male Tukrculws Mortality Rates l - - .--1...- . ::: 1 ...... i ;;.ec -.. .- I ...... - -- - . --- . -> .- .- t ...... -...... , A?. ,= ...... , ...... --, -= - -. a.-- ...... Figure If: PaItial Autocanelatm Funcbon of Log-Trandorrned and Differenced Male Tuôerculosts Mortaltty Rates .,. . .- S.. ... - *- Figure 2a: AutocomlstKHl Funcbon of ARMA (0.1.1) Residuals of Male Tubefculosts Mortrrlrty Rates ...... ;....#...... ; ...... -.- .:...... -1 ;...-...... < ...... - ...... ;...... - A...... ,...... A...... , Figure 2b: Partial Autocarrefation Function of ARlMA (O 1 1 1 Resduals of Male Tuberculosis Mortalny Rates f bure Zc: Hwogram of ARlMA (0.1.1) Raaiduis of Male Tubarcuksis Mortalrty Ratas -2.4 -2.0 -1 6 -1 2 -0.8 -0.4 0.0 0.4 0.8 1.2 1.6 - Expectd -2.2 -1 8 -1 4 -1.0 -0.6 -0.2 02 0.6 1.0 1.4 1.8 Normal Upper Boundanes (x<=boundary) Figure a: Autm- Function of Differenctd Female Tubcnulosis Mortality Rates . _.-- . - -..- * _-..-- -.-.- k .-- . - .- . .-...... m..... -- - -.-. - . . - --- i ...... :...... -.;...... a-. -- - .-...... &...... -...... ;...... ' .-- - . - . - -- . - -i; 3 Ili --.-- ...... ,...... 2 ...... - --. - - .--T . ;;; if: - --.- --- . - . . . - . - ._--- ..-...... L ...... i ...... t.....;...... i ...... -.- --': . - .- - r...... iii ' . - ...... a- ...... ~...... --.... . -- .-. - - ...... ~...... -...... --.- ...... _...... -- -- - .-S. ... - --. -- -. -- - ...... -...... - --.. - . - - -. - .- -- -...... - ...... - -1. >': - - -. -. ., * - .&- ..-- ...... *- ...... - -*. -3 -- . . -2 -...... -...... - --. -. . - . - .- . ,.._ d - . - ...... *...... -d. -- ..- . ; 1 -#'? - . .+ -c .- -- . -- ...... ,...... - ,di .t .- -- ...... a...... ; -.-1- ...... - - .-4- - ,. .-- ...... --- --. -* - ..-- . -+. . -1 O -0.5 0.0 0.5 1 .O Figure 3b: Partial Autoconeiatmn Function of Differenced Female Tuberculosis Mortality Rates Figura Ir: Autocorrebion Funchon of ARlMA (0.1 .1) Residuak of Famale Tukrcuksrs MMtsrity rab^ ...... 3;; ...... ;...... ;...a...... '...... ; ...... -...- ...... a...... +i ...... ;....*...... ; ...... - ...... ,...... ;...*..B...i...... *- ...... i...... ; ...... l...i...... i...... - ...... L ...... iiiiit-.....; ...... i...... - ...... * ...... i...... ;...... - ...... ; ...... i ...... W.. ; ...... ; ....-...... - ...... ; ...... 8 ....; ...... j .*...... - ...... ;a; <...... - ...... --.-- ...... Figure 4b: Partml Autocombtton Functton of ARlMA (0.1.l) Residuak of Female Tuberculosis Mortalrty Rates ...... *...... __...... :*:...... ,...... - ...... & ...... !...... : ...... -...*.- ...... ~.iii.ii~...... $...... *...... i ...... **...... ~ ...... -...... :b ...... (...... *...... i b...... - ...... i ...... '--".... * ...... M.....- ...... +...... * ;a: b...... !.....im ...... a...... ; ...... m...... - ...... a..... ;...... - .....- ...... *...iiiiiiiii+!j...... :...... *; ...... - ...... S...... Li...... ,...... 1,." .... "..".."...... "...... ! "". .. '...."...... 1 Figum Ic: Hmtqram of ARIMA (0,l.l)Residuais of Femaie Tubanubsis Mortality Rates 55 - SQ "-.-...... -.-...... -.....*.....*...... Figure 4d: Normal Probabilrty Plot of ARlMA (0.1.1) Residuals of Fernale Tubwculoais Mortaliity Rates Figure 6a: A- Function of Figure 6b: Partial Autocorrelation FunctKHi Differenced Male Pulrnmfy Tubsrcutosw Mortality Rates Figure 6a: AuummWm Function of .-- . . - ..-- 'f ...... A...... -...... ;...... - ....$37.; . - 3.: ;. .& -. a - ---7; ...... - ..- iiiji - . -. -*- .-. a- . -4; ...... <...... -..- 5.,f .:s.r; - -- i ... +. . .; ...... L...... ; ...... m...; ...... ; ...... - --. .:Lee ... ..- j - .-. -.--!A . . .--.- ...... ;..m.; ...... *.*;...... -.-- .:545 . - .:.....- - .: ...... ,...... ; B; r...... - f.E2 .IbZc ...... - . .-- . .-. r -..,...... ;a: ?.++ .:g-: - .- -. - ...... -...... es.- - - . --.. , ; 1: .. -- .,l*S . . ..- .* .- -...- ...... -...... A.. . :- .:96: .- -...... - -.ie...... -- ...... - . .;-IO5 -. . - .- -- -. . +- ...... - . c .3;97 , . -. 'CGC ...... _...... -"-L -. . a- ...... - il. v . . . - -- . .-.--- - ...... - .Y .::oc , . - . - - .- - ...... - - . .-i;c . - . -- ...... A.... *- U . --. - .-- 1...... j*...... -.- . 1 Figure 6b: Partial Auîoconelation Functton of ARMA (O.?.1 ) Residwls of Differenced Male Pulmonary Tuberculosis Mortality Rates Figure 6c Hm2qram of ARMA (0.1.1 ) Residuals of Male PulmryTukrcuksrs hrkrtality Rates Figure 6â: Nomial Proôaùiiii Plot of ARMA (0,1,1) Residuak of Male Pulmonary Tuberculoss Mortaiii Rates Fgum ta: Autoconslition Function of Oifferenced Famak Pulmwary Tubarcuksis Mortility Rates . 0553 ...... +.: m...... l...... *.' ...... * *-.. : 2:-- . ,2349 -.-...... : ...... -.: b 7" . c ...... -W. ; * * 29;; ...... : ...( ...... -* -9 ...... ;..u ...... -- .-l- . jgj;: ...... ;{ ...... j ;...... , 2: -4; -.qat .....? & "' =- .-d- ...... , . ,...... ; 1; --.4- -. . :3,: ...... i...... *.* i...... * i...... - --.-- - - . :316 ...... i ...... i ..... 1...... ; ...... i ...... ---- . - - ;...... - .L'42: '-...... A ...... i mi --.-c Ji: ~cji:- .*...... b ...... 4 ...... -5.;~ . figlz ...... j...... ;...a.....*; -...... ; ...... ,- 2; -2; ^' . -.?O7 W., ...... ; <...... - - .--.- "' . ;933 ,...... ;...... ; Bi ..... :-...... -...; ...... 3 - ._--- *:Je$ ...... L ...... ;...a...... -.-- -- ..a?-- ...... A."" ...... !. ....>...... A...... , -.:- ..'I -- - -. . i...... - ...... 8. ....r...... ;...... , --.;. :. C -1 .O -0.5 0.0 0.5 1 .O Figure Tb: Partial Autocondation Fun- Differenced Femaie Pulmonary Tubsrculos#r MortalRy Rates f igun k: Fundi#i of ARMA (0,1,1) Rsriduib of Fefnaie Pulmorisry Tukrcukui Martslity Ratas Figure Ob: Partml Autoamdath Funcm of Female Pulmonary Tuberculasis Mortality Rates Là< Zcrr. -.-.-. ..- ' - - -... . "...... :t: .------. -*: . ;;-...... !...... # ...... :...... ; ...... " . - -.- .-- C . ai-...... m...-..,...... - .- 1 -.,-" ..?y ...... ;...... #.. .-..*...f..-....--..--...... ,*...... -.." - 5 -.;as ...... -- ...... ;...... S...... i...... :...... *...... " . -- * .-- - .--.." . -y - ...... ,...... i..*...... -...... -..- - .-- A.4. .-- . +- ...... b...... " . ------. &CC . 4,- ...... r.....-...+r...... i. - - .. ------. . 4- - ...... " -. - - .C - - ..-&- . Y ...... -..-...... _...... *_._-*--*--...... *...._ . .- -'- -- ...... t...... -- - . a-- .-? . .j ...... ;..---...... - -- - .------...... - .------.--- - . *F " ...... t..*...... *.*...... "...... - , --- . ,* -.,:= . ?6- ...... < ~...... i 5 ...... -...... ;..*.* ...... i.i.i. - - - . 4 ...ce- ...... --...... :...... : *: -1 .O -0.5 0.0 0.5 1 .O Figure 8d: Normal Probaklity Plot of ARMA (0.1.1) Residuals of Fernale PulmryT uberculoois Mortalrty Rates VALUE REFERENCES -4ir Ministry. M. O 1962 Weuther ai the Mediierranem~,loi. 1. Her Majesty's Stationery Office Anderson, M. 1 996 British Populaibl History. Cambridge University Press. Cambridge. .hiaga. E. 1 994 Popularrot~.A tta!iws with Microcornputers. U.S. Bureau of t he Census, New York Avala 1 78 2 Historra de Gr brcrlrar. 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