ocP/ 85 . 5
I^IORLD HEAITH ORGANIZATION onchocerclasis Control Programme in the Volta Rlver Basin area B.P. 549 - Ouagadougou t Burkina Faso
ONCHOCERCIASIS FOCUS IN THE BISSA COUNTRY by A. Rolland and G. BalaY
New edltion, November 1985
I ocP/8s.5 Page 2 FOREWORD
The rernarkable work by A. Rolland and G. Balay on the onchocerclasis focus in the Blssa country, which was greatly in advance of its time (f969), was unfortunately never publlshed, although it thoroughly nerited to be so; havlng remained a report of the Onchocerciasls DepartnenE of OCCGE, it r.ras known only to t.he privileged few, for whom i.t was a valuable source of reference.
Ihis document is ln effect the result of the first rational mulEidiscipllnary approach to a focus of onchocerclasis; several of the ideas put forward in it have now become basic to the epideniology of the disease; although the work of a physician and an entomologlst, the socloeconomic study that it enbodles was to be the startlng point for the research of those ethnographers and geographers who were to concern themselves wlth onchocerciasis during the next 15 years.
At the time when the report was produced, no onchocerciasls control canpaign had been undertaken ln the east of rrhat is now Burkino Faso. Preclse and sober as 1t is, this report gives a.moving descrlption of the catastrophlc situation that prevailed at the tine in the Volta river valleys wlth regard to health and the socioecononlc sltuatLon, a situation which also existed in all the valleys of the major watercourses in the West African savannas; this viclous circle of disease and poverty led lnevitably to the bllndness and early decline of individuals and to the death of their cornmunltles.
The Onchocerciasis Control Programme in the Volta River Basin area (OCP) was set up ln 1974, and vector control was lnstituted as from L977 in the baslns of the White Volta and the Red Vo1ta, whlch lrrigate the Bissa country; entomological surveillance has not been relaxed since that tlne.
Today, nldway through the original 20 yearsr lifespan of the OCP, it can be stated that the cllnical and socioeconomic picture of the kind described in the report by Rolland and Balay no longer exists ln the Bissa focus, or for that matter la 90% of the 764 000 kmz currently treated by the Programme. How is this reality reflected in the villages that were studied during the 1960s? In Nlarba, a vlllage whose population has continuously declined under the effect of onchocerclasls si.nce lts decioati.on at the time of the ravage of the di.sease (roore than 802 of the populatlon lnfected and more than 102 bLlnd both ln 1969 and in 1976), transmlssion fell fron a leve1 of 2700 (1969) to 0 (1978) and has remained lnterrupted slnce then; between 1976 aad 1985 total prevalence decreased fron 812 to 3QZ and ocular parasitisn in adults from 797" to 2%.
In Yakala, which Iras a reference village ln the Rolland and Balay study, the transmlsslon rate feIl fron 800 in 1969 to 0 fron 1978 to the present date, prevalence was reduced froa 762 to 36't! and the ocular parasitism of adults fton 74% to ZZ between 1976 and 1985.
Even more striking than these figures, however, are the changes that have taken place in the socloeconooic environment and the uentallty of the lnhabltants, for example in yakala. The nunber of fanilies of 1oca1 origln fell from 11 1n 1969 to 8 in 1976, since when 24 famllles have moved ln (15 of then settled), thus lncreasing the total population from 100 to trore than 300; over the same period the Fongou district on the other bank of the white Volta took ln 20 to 30 fanilies which all settled, thereby raising the population of the dlstrict from 400 to nearly 1000.
For the inltlal lnhabitants, the Bissa, who have been established in the area for uore than a century, blackflles have disappeared and onchocerciasis is beaten; the tine i.s gone when "you had to marry young because from the age of 25 onwards you could no longer a woman". As regards the numerous inmlgrants and the young people born durlng tfie last".r"r, """ decade, they know nothlng about blackflies and Eheir knowledge of the disease is confined to the blind "old people" of Bissa, survLvors froru a period regarded as over and done wlth. There is no shorEage of available, fertile 1and, and the grain stores contaln sufficient reserves to carry over fron one annual harvest to the next; a health post has been opened, ocP/85. s Page 3 another is being set up and a well has been dug; t,here are deuands for a dispensatYt a school and a borehole, all evidence of the will of the people to persevere with the lmprovement of their socioeconomic condltions.
There, as in rnany regions of the area covered by OCP, villages are coming back to life and a true process of self-development has been set in notion in the lands along the river banks, which have been rendered healthy and transformed from the centre of repulsionr whi.ch once they were, to poles of attraction. This upsurge and relative wellbeing are natural to an uninformed observer. One of the reasons why thls report by Rolland and Balay is of interest is preclsely because it enables us to assess ghe advances that have been made over Ehe last 10 years, in relatlon to an initially catastrophic situation, and to realise the effectiveness and the fuopact of the Onchocerciasis Control Programme. At a tine when the spectre of onchocerciasis ls fading over vast areas, such a docuuent is also tiroely in recalling to all those concerned by the disease, governlDents, donors, and officials responsible for health, developrnent and the control of endenic dlseasesr the gerrible reallty of river blindness and the pressing need to continue to fight it until return to the draoat,ic siEuaEions describdd in the document becomes inposslble. This report also remlnds us that sinilar situations of physical wretchedness, social decay and despair ascribable to onchocerciasls are stlll the 1ot of tens of thousands of African villagers outs.Lde the present OCP boundaries, for whom Premature blindness and the abandonnent of thelr land was an inevitable fate, but to whon the achievements of OCP have given rise to tremendous hoPe. Lastly, the reissuing of thls report, whtch sets out the infornatlon that Provlded the basls for OCP In the east of Burkina Faso, enables us to Pay homage to the generatlon of doctors, entomologists, nurses, technlcians, auxlllari.es and insect collectors who were the forerunners of the onchocerciasls programme; following Physician-General P. Richet, the great promoter of oncherciasis control, these men gave of their best fron 1937 onwards, and itf" i" particular in the Blssa focus, to deuonstrate the serlousness of the problem and the posslbility of combating iE; this they did at a time when the valleys' emPty of human beiogs, had been abandoned to the bush and to the wild fauna, when prospecting was carrled out on foot or in small boats and dugout canoes, and when ophthalmological examinations took place between grain stores ln the very relative coolness of the shade of the mango trees.
Through the reading of this report, which is at last brought out, let the example of these pioneers contlnue to inspire their successors in the exemplary undertaking of the restor;tion of human dignity, irhich is the be all and end all of the Onchocerciasls Control prograuroe in the Volta Rlver Basln area, the future Onehocerciasis Control Programme in West Africa.
B. Philippon 0ctober 1985 ocP/85.5 Page 4
The following have also contributed to the new edition of this report: - the Ministry of Public Health of Burkina Faso; - the organizatlon for Coordlnation and Cooperation in the Control of the Major Endernic Diseases (Organlsation de Coordination et de Cooperation pour Ia lutte contre 1es Grandes End6nles - OCCGE) ' whtch have given their permission for the publicatlon of the report "Onchocerclasls focus in the Bissa count,ry" under the auspices of OCP; - Dr E.M. Sanba, who supported the idea of thls republlcatlon frorn the outset; - Professor C. Pairault; - Mr M. Gaud; - Dr A.N.L. Dounbate; - The physiclans of the OCP Epldeniological Evaluatlon Unit' through the communlcatlon of lnformatlon on the present situatlon in the vlllages of Fongou, Niarba and Yakala; - Dr R. Le Berre, through hls co'nrnents on the report, the preparatlon of whlch he had initiated ln hls tlne. Our thanks to then. ocP/ 85 . 5 Page 5
OCCGE I,IINISTRY OF PUBLIC HEALTH AND WELFARE OF UPPER VOLTA
CENTRE MURAZ DIRECTORATE OF RURAL IIEALTH
ONCHOCERCIASIS DEPARTMENT
No. 111/oNCHo/of 30.05.1969
ONCHOCERCIASIS FOCUS IN THE BISSA COUNTRY by A. Rolland* and G. Balay:t*
* Chi"f Physician, Mobile Ophthalnologieal Unit - Dlrectorate of Rural Health - Mlnistry of Publlc Health and Welfare - Ouagadougou - Upper Volta. ** oRSTOM Medical Entonologist - Head of the Ouagadougou Unit - Onchocerciasis Department of the Centre Muraz - Bobo-Dloulasso - Upper Volta. 0cP/85. 5 Page 6
ONCHOCERCIASIS FOCUS IN THE BISSA COUNTRY
CONTENTS
Page
10
CHAPTER I - BACKGROUND INFORMATION ON THE BISSA COUNTRY
1 The country 11 2 The people 11 3 Economlc organization of the Bissa country 11
CHAPTER II - THE VECTOR: Slmulium damnosum Th. (*) 1. Method of work 15 1.1 Preimaginal habitats (Iarval breeding sites) 15 L.2 Bioecological study of fernale blackfly 15 2. ResuIEs from observations of the breeding sites of S. dannosum . 16 2.L Site location .. 16 2.2 Seasonal variations of the distribution and size of breeding sites in relation to hydrological variaEions 16 3. Bloecological study of blackfly fenales L7
3.1 Population dynamics t7 3.1.1 Seasonal variations of daily counts L7 3.L.2 Seasonal variations of the average physiologlcal age of female populations 18
3.2 Daily biEing pat.tern 20 3.3 Infestation by O. volvulus ln blackfly 2L
3.3. 1 Seasonal variations 2l 3.3.2 Daily observations 23 3.3.3 Other remarks 23
3.4 Variations in the populatlon of blackfly females as a function of distance from breeding sites 23 3.5 Study of the transmission of onchocerciasis . 24 4. Other observations ...... 26
4.L Parasites of S. damnosum fenales 26 4.2 Other species of Siuuliidae .. 26 4.2.L In preinaginal habitats (breeding sites) ... 26 4.2.2 CoLlected by human bait . 26
* Elsewhere ln the text Simulltrm damnosum deslgnates all Sinuliuro species now grouped together as the S. damnosum coopfex. Cytotaxonomic tdentifications after 1969 suggest that thE species with-ffiTEG study ls concerned were nainly S. sirbanum and E:1!51g1111gg s.s. (Editorlal note) ocP/85. 5 Page 7
Page
CHAPTER III - ONCHOCERCIASIS 1. Background information 27 2. Clinical study 27
2.L Extent of the disease . 27 2.2 Distribution of the disease 27 2.3 Seriousness of the disease 28 2.3.L Selection of villages 28 2.3.2 Examination method .. 28 3. Epidemlology of ocular complicatlons 30 3.1 First-1lne villages 30 3.2 Second-l1ne villages 31 3.3 Thlrd-line village . 31
4 Sex dlstrlbutlon of eye disorders 31
5 General conpllcations of onchocerclasis. Pathologlcal associatlons 42 5.1 Endemoepldenlc diseases of the Bissa focus 42 5.2 Other endemic dlseases .. 43 5.3 Nutrltlonal deficiencies 43 5.4 Ceneral dlsorders of onchocerclasls patients 44 Survey on the general condltlon of persons infested with O. volvulus ln the Bissa country. 45 6. Concluslons 46
CHAPTER IV - THE ASANDOMENT OF THE VALLEYS 1. Study based on adninistrative records 47
1.1 Census of the total Bissa population 47 L.2 General evolution of the Bissa populdtlon 47 1.3 Evolutlon of the population in the lndivldual cantons 47 L.4 Evolution of the population 1n the vlllages within the indlvidual cantons 48
2. Survey among the populations 48
2.L Method of work 48
2.L,2 Standard questionnaire 48 2.L.3 Persons questioned 51 2.L.4 Recordlng the results 51
2.2 Results of the survey 51
2.2.L Name and situation of the abandoned villages and quarters . 51 2.2.2 Orlgin of the abandoned villages 52 2.2.3 Size of the abandoned villages 52 2.2.4 Date when the vtllages were abandoned 52 2.2.5 Survival span of the 18 recently established villages or settleEents 52 ocP/85. 5 Page 8 Page
2.2.6 Way in which the villages disappeared 52 2.2.7 Places to which the inhabitants of the abandoned villages noved 52 2.2.8 Changes in the frontier of the cultivated area 53
2.3 Reasons for the abandonment of the villages according to their populations 53
2.3.L Danage caused by t^rild animals 53 2.3.2 Compulsory recruitment of labour 53 2.3.3 Diseases 53 2.3.4 Various causes 54 2.4 Possibilities of the population returning to the abandoned areas 54 3. Crltical study of the causes of the abandonnent of the valleys 55
3.I Summary of the characteristics of the movement away fron the valleys 55 3.2 Factors leading to the abandonment of the valleys 55 3.2.1 Factors that have disappeared or which no longer play a part 55 3.2.2 Factors still presenE ..... 58 4. Denographic study of a village where onchocerciasis is hyperendenic ..... 60 4.L Situation of Yakala village 60 4.2 The dernographic evolution of Yakala village fron 1963 to 1968 60 4.3 Concluslons 68 5. Study of a particular case: the Niaogho region 69
CHAPTER V - THE CONDITIONS UNDER I,IHICH CULTIVABLE LAND CAN BE RECOVERED 1. Studles of various possibilities of controlling S. damnosum 7L 1.1 General characteristics of a control canpaign 7t 1.r.1 Framework 7t 1.L.2 Definition of the objectlves . 7L 1.1.3 The control rnethods at present used 7L 1.2 Selection of a control Project 72 L.2 I Insect.icide barrier 72 L.2 2 Local larviciding canPaign 73 1.2 3 The building of large dams 74 2. Role of treatment in onchocerciasis control 75 2.L Ihe aius of an onchocerciasis treatnent campaign 75 2.2 The means of treatment, their effectiveness and their dangers 75 2.3 PaEients to be treated 77 2.3.t The villages 77 2.3.2 Age-groups 77 ocP/85. 5 Page 9
Page
2.4 Selection of type of treatment 77 2.5 Organization of the treatment campaign 77 2.5.L Fixed treatment bases and staff 77 2.5.2 Materials and medicaments needed 78 2.5.3 Duration of treatment 78 2.5.4 Cost of the treatment campaign ... 78 3. Conclusions .... 78
ACKNOI,ILEDGEMENTS 79
SU,IMARY 79 FIGS 1 - 8 .. 80
REFERENCES 88 ocP/85.5 Page 10
INTRODUCTION
The Bissa onchocerciasis focus is, thanks to P. Richet, the one vrhich has been known the longesE in l.{est Africa. Nevertheless, rre undertook a systematic study of it durlng the last few years for several reasons:
(1) The Bissa people has the unfortunate distinction of belng entlrely confined to an area in whlch onchocercal infestatlon is extreneJ.y high. The Btssa country is an evident choice for anyone who wishes to examlne not only the problems of the distribution of the vector and of the disease, but also the economic and soclal aspects of this parasiEosls. (2) The economists of the Upper Volta have long been interested in the scope for agrlcultural development of this potentially rich country, with it.s vast area of uncultivated fertile land and the excellent work of the farmers of Niaogho on the White Volta in market gardeninS.
(3) The plan for the agrlcultural development of the Upper Vo1ta and the launching of the AI,RO 131 project for the reglonal control of onchocerciasis by the World Health Organlzation have now nadE the problem of land resettlenent and the control of onchocerciasls immediaEe and urgent tasks for t.he country.
Our personal work was initially nedical, entomological and cllnical, but when we decided to consider the problen of onchocerclasls control we felt the need to clarify the soclal and human aspects of thls parasltosis: the abandonment of villages and the retreat of the frontler of cultlvatlon line in the hlstorical and geographical context of the Bissa counEry-
I,le therefore adopted the following plan for our study: 1. A general presentation of the Blssa country 2. A review of the entomological and rnedical situation 3. A study on the contributlon of the disease to the abandonment of Ehe valleys 4. Examlnation of possibilities for onchocerciasls control
We shall consider ourselves conpletely satisfled should this work, which has resulted fron a close collaborat,ion, be able to contribute, even ln a nodest way' to the economic development of a people rrhon we regard as especially sympathetic, and to the iroprovernent of thelr state of health. ocP/85. s Page 1 I CHAPTER I - BACKGROUND INFORMATION ON IHE BISSA COUNTRY 1. The country The Bissa corrrltr,v (Figs. 1 and 2) is located in the south-east of the Uppe! Volta on the frontier with Ghana (between latitude 11o and 12o north and between lqngitude O" and 1o wesE). It forms a homogeneous whole with an area of about 6300 knz. It is quasi-plain with an altitude of 180m at iEs lowest, and 40On at its highest. point. Climatologically speaklng, the Blssa country, which lies between the 850 mn and the 1050 un isohyets, is a part of the Sudanese savanna zone. The Sudanese climate alternates between two highly contrasEing seasons:
The dry season (from November through May), which may be subdivided into: - a "co1d" dry season (Novenber to February), during whlch two dry wlnds blow, one from the east, the other from the north-east (the harmattan and the northern trade wlnd). The typical features of this season are its extremely 1ow humldity and its low nighttiroe tenperatures ; - a hot dry season (March to May) during which a current of moist air coming from the west-south-west (the roonsoon) appears and gradually establlshes ltself. Daytlne teoperatures are high, frequently above 40-C.
The ralny season (June to October), durlng which daytime temperature remains falrly low; on the other hand, moisture content reaches its maximum. The average annual ralnfall reaches 900 nm 1n 62 days of rain at Garango. The river network consists of:
- a part of the middle reach of the White Volta and some of lts principal trlbutaries (Dougoula Mondi, Tcherbo, Noahou);
- a short stretch of the Red Volta bounding the Bissa country in the south-west. A11 these lsatercourses stop flowing entlrely during the dry season.
2 The people The Blssa ethnic group consists of about 200 000 people grouped into four administratlve districts: 2 cercles* (Garango and Zabr6) entirely Bissa 2 cercles (Tenkodogo and Manga) predoninately {ossi Thls populati.on ls unequally dlstributed: the valleys of the Volta rivers and of their nain trlbutarles in fact constitute an uninhabited area of roughly 3000 kn2. (The only vlllages on the banks of the Volta rlvers are to be found in the Niaogho and Yakala areas on the White Volta). Ihis denographic vacuum represents nearly one half of the Bissa terrltory. Population density calculated in relatlon to the area of the cercles is 42.29 lnhabitants per koz for the Garango cercle, 25.5O for the Zabr{ cercle. In fact, these cercles include large uninhabited areas, and the population density in the lnhabited areas is conslderably higher than these figures. The Bissa people forms a homogeneous group litera11y enclosed betrdeen the other Volta peoples that surround lt on all sides: the Mossl to the north, east and west, the Kass6na, Nankana and Kousas6 to the south (see Fig. 2) and the practically deserted banks of the Red and Wtrlte Voltas, the Noahou and the Dougoula Mondi. 3. Economic organization of the Bissa counEry
We shall borrow this chapter from the work by Sister J. Bernard (Odette Pageard) - 1965; Ire quote: "The Blssa are a conpletely agricultural people, as ls clearly shown by thelr view of the year. For them, the cycle, the rhythrn of life, begins in the month that we call May and ends in Decenber. Decerober to May is a slack period".
* AdministraEive disEricts - translator. ocP/85. 5 Page 12
The perlods of the year June, July - "the tlme of digging and cultivation" August, Septeober - second digging, the nont.hs of comnunal labour october, Noverober - harvest Decenber - bringlng in the harvest. Once the harvest is In the barns, Ehe year is over. The divlsion of labour between the sexes and the cultivation timetable
Reference is made to the following tables taken from the same work by Sister J. Bernard (Tables 1 and 2).
These tables are useful for an understandlng of the times of the year at whlch Blssa men and wonen are in contact, although ln a different manner, wlth the blackfly vector of onchocerciasis. Thls w111 be the subject'of the following sections. ocP/85.5 page 13
TABLE 1. DIVISION OF LABOTTR AI4ONG THE BISSA
Men Women Boys Girls
Crops of rice + + large millet + + + + snal1 mlllet + + red miI1et + + maize + + srileet potatoes, yams + Peas + groundnuts ? + plants for flavourlng + cotton +
Grubblng + Manuri.ng (horses, asses, goats) + Dlgglng + + + + Weeding + + Harvestlng ni1let: cutting steEs + cutting heads + brlnging ln nillet + threshing + grinding + + Gathering: flavouring plants, shea nut, locust bean + + Transportatlon of water + + + of wood + + + Cooking + + Dolo + Carding + Splnnlng + Setting up warp threads for weaving + + Weaving cloth + Dyeing + Fenclng + Manufacture of ropes + + thread + wooden objects + basketrrork + cooking pots + + Manufacture of bricks + water Hut bulldlng + Rough-castlng and ramming + + Roofs + Huntlng + Flshlng + Shea butter + Soap + Washing clothes (of the husband or brothers) + ocP/85. s Page 14
lqr (d (!0(u .cu O+J o\o .c @o o. r{ hI) (atr(06 (t r(u .r{ o. o ts.I q ,ri v) o(dtr(d! oo @ E oc x @+J r, ti c,rr! $ t{ Q@ O @@ .dtr (u +4 L O lJ l. d +J: ..{ a I. 'H IJ CT, Fl o oo kro o 14{ ..1 o >.c E o a-{ !h r+{Joo do U+J (J C o, l+{'! lr-C tr oo (! Ot lq lZ oo'+{ud 3tr (, c.{:' -IJ x o0 @ ! tr! t (0 .r{ o rl dx,(! +Jtr-{ FI J'Ooo 6' 0JO F, lZ !EE (/lB
Jo,ooo @F{ tr r0) tr-.{ 6 lr lqFt d .Fl F{ O\O ,o(d rrErr @ AO trp O O -rr l+) E(! .r{ tr OF{ U o O .,i 0) o!z rro(! >F{r{ CF{ UFI U C ..{ !, lr qt tr (!F{ UFI od orJo rdEd0Jd a.A a> (J (!F{ fr(/,.cAE c)E
tr o I c ,.o o .i a J Ntr OE^(s & o +{O oo (0 (0 @rJ -lBl{ o Etru @o ,. O o z \o +, .HO du oE z I @rJ O Fi,TE EI l{ '.,{6r, aa pdFul FI o pobo .r{ 6 o'd (0 +{ ! otr rJF{ O otr E o C) o(0 r!>.H o o.o >aoootJ utt utr> oo frO(UFl+lO a oo O coF{ ) -g 6tJ(D.calJ a OE H-c b0 li h0(0 id o0o.B Ou, H (6trr, E..t O EA lr @o loo o @ IJ)E frl p 0)orJ E cE 0j J r{ H o oo oo '+{o! E U u tUF{ cd O O A lJr)o^! .o O - O0 > Oo.F{ O o oo) 'o\o tr c-c!{ 6t (, t(u OF{ ^ F{il€d } r{ l-l F{O @^OrJtrtrt U(! @'r{ > d oo(u o (! 3 o ld ora cE(U tl tr xo o o tr 'J a F{O oDF{ > rU > > d FE OOt Bto ooll t{ }r fJ (! d E ,o oqro .Fl <0 O t0Jl-l O O H
o Fi (! o ..O Orl .U .H q) c oFt o p -&, ojl E @o o trtl Elr t! trY{ o 0Jo oo 2trl Eq tq EB BB ocP/ 85 . 5 Page 15
CHAPTER II - THE VECTOR: Siuuliun damnosum Th. The entomological survey carried out in the onchocerciasis focus of the Bissa country was mainly concerned wlth the following two asPects: - search for the preinaginal breeding sites of Simulium damnosum and study of their evolutj.on in relation to hydrological variations;
- sEudy of the bioecology of females of the species.
1. Method of work 1.1 PreimagLnal habitats (1arval breeding sites) Three methods were used in seeking out and nonitoring preimaginal habltats: - The systematic prospecting of watercourses by notorboat. This method, which yields the largest amount of information, was used to prospect the ualn channels of the White and Red Volta rlvers;
- Overflying at 1or.r altitude. Thanks to the loan of the "Broussard" aircrafE, belonglng to the Enbassy of France in Upper Volta, we were thus able to vlsit the Dougoula Irlondl, the Soussougou, the Silnisilido and the Kou1lp€16. Although this rnethod does not provlde complete results, it has the advantage of being rapld, of naklng it possible to vLsit watercourses that are dlfflcult to access 1n the rainy season and of discoverlng all large and medium-size habltats; - Prospecting on the ground, essentially by visitlng various watercourses at points where they are crossed by a road or track. The larvae cnd pupae collected were subsequently identified ln the laboratory of the Ouagadougou unit. 7.2 Bioecological study of fenale blackfly
This study was carried out by catchlng S. damnosum females on human bait. Two trapping systems were employed: - serles of collections spread out over the whole yearly period during which the fernales blte actively, at a rate (in as far as posslble) of one day of collection every two weeks at each point selected (Figs. 6 and 7): Polnts A and D on the maln channel of the trlhi.te Volta; Point F on the main channel of the Red Volta; Point B on a soall right-bank tributary of the White Volta.
- perrDanent camps (dai1y collections) set up at points E (natn channel of the White Volta) and F (referred to above) during the period between the disappearance and the reappearance of larval breeding sites in the Volta rLvers (between January and l,tay).
A11 these collectlons r{ere made at each polnt from dawn to dusk by a collecEor who was always positioned In the same place and replaced every two hours.
Most of the females collected were dlssected on the spot, shortly after capture, by the usual procedure employed in the onchocercj.asis department of the Centre PIuraz (Le Berre, 1966, p.7) to determlne ln particular their psysiological age and their rate of infestation by Onchocerca volvuIus. ocP/85.5 Page 16
2 Results from observations of the breeding sites of S. damnosum 2.1 Site location
Those larval breeding sites of S. damnosum that have so far been recorded in the river network of lnterest to us are shown on Figs 5, 6, and 7. It should be pointed out E,hat whereas the main channels of the two Volta rivers and of some of their tributaries (Silmisilldo, Koulip616, Soussougou, Dougoula Mondi) have been systeoatically prospecEed by (p1ane and boat), other trlbutari-es have been visited nore irregularly. It is, in general, not possibte to use the above-oentioned working meEhods because of the density of the forest cover on nost of these smal1 watercourses, and the narrowness and obstruction of their beds. One is therefore obliged to fa1l back on prospecting on foot, following the bed of the watercourse. Glven the period (August-Septenber) when these vlslts are to be carried out, the working conditlous are extiemety difficult (1ack of tracks, continuous walking in mud, through thick, water-sodden vegetation, the crosslng of flooded lowlands and secondary ldatercourses in sPate' frequent ralnfall), and ghe output is especially low. Consequently, our investigations on these watercourses were in general limlted to sample surveys of polnts readlly accesslble from the exlsting road networkl Visits to the upper reaches of most of then conflrned the fact, already noted by us and by the entomologlsts of Bobo-Dloulasso (Le Berre t L966), that S. damnosum seems only rarely capable of establlshing its breeding sltes less than 6 to 8 km frou the source of the watercoursesr even lf the condltions are at flrst sight favourable (Iarval supports submerged ln sufficlently fast currents). The explanation for this phenomenon would appear to be the lack of food for the larvae of the specles (Le Berre, 1966, pp. Laz-La7). This iltuatlon oay, horrever, be nodifled by the creatlon of an artlficlal lake (by damning), as we had been able to note at the varlous sEall dams vislEed in our study area (tlnkodogo, G"."rrgo, Manga, Zabrl), all of which had habltats of S. damnosum ln thelr spillways. However, on the basls of the experience acqulred in the course of nearly seven y".." fn this area, rre consider that alnost all trlbutaries that. had a bed at least 8-10 kn iong, and dlscharged dlrectly into the Volta rlvers, do have breeding sites of the species, at ieast in their lower reaches. Thls is especially so of the trlbutaries that we have shown on our maps (Figs. 5, 6 and 7). 2.2 Seasonal variations of the distrlbutlon and size of breedi sites ln relation to lcal var ons River flow is completely halted for a part of Ehe dry season in the area that we are studying, when no permanent breedlng site of S. dannosum can be-found.- This cessatlon of flow lasts on aver;ge for two to four months in-TEa nain channels of the two Voltas (February to April in the White Volta, January to Aprtl in the Red Volta). IE appears to be markedly tonglr in most of the tributarles, Ehe smallesE of which have continuous flow for only three or four Eonths of the year during the rainy season. With the first big rains the first habltats appear between April and June in the maln channels of the Volta rivers and in the Noahou, with colonlzation generally taking place from the lower reaches to the upper reaches (observatlon identical to that of Lamontellerle, 1964). Thls colonlzation then extends to the large tributaries (roore especially the Dougoula t"tondi and the Kou1ip616) in June and July and does not reach the snall Iratercourses untll July-August. When ihe i..tt". begin to flow, the presence of an already qulte considerable poplt"tlol of feuales derived fron the large ldatercourses results in plentiful "seedln8" of it"i. habltats, which then nultiply very rapldly. The surface area of S. daelqqlqhabitats reaches Lts annual naximum at this tirue (August-Septenber). These breedlng sites seem ln general to be numerous ln the lower reaches of the rnain tributarles, in a large Part of the Io,r."" of the Red volta in the area under investigation by us and ln the course of the white Volta around and upstream from point A (Figs. 5, 6 and 7). Given that most of the rock steps are submerged at tirat tlme by the flood, these habltats are almost always establlshed in elbows or narrow polnts of the bed, where profuse vegetatlon offers a great variety of support Eo the preinaglnal forms. Breedlng sttes are, on the whole, less numerous in the of the whlte volta between polnt A and the frontier of Ghana or^7in8 to the type of bed "o,rr""(large and not especially tortuous) and the decreaslng number of supports (bank vegetatlon and esseniially concentrated on the steep Portlon of ehe banks). The abating of the fiood,"p"ri". often occurrlng abruptly, generally durlng the second half of the rnonth of September, inEeriupts the developr".,t and seriously affects the output of most of the sltes (those of ocP/85. s
page 1 7 the tributaries in particular) as a result of the rapid drying out of supports for preimaginal forms. As through-flow ceases, the habitats of the tributaries disappear (0ctober-Novernber). A11 that ultinately renain are the breeding sites of the main courses of the two Volta rj.vers. These sites, the number of which has sometimes been increased by the immerslon of numerous rock slabs (more especially the White Volta), may then (November) undergo relatively considerable developnent (such as, for example, the appearance of floodable causerray at Yakala). The last S. damnosum breeding sites generally disappear a few days bef ore the total cessation of througFf,ffilli-The Volta rivers (January to February). 3. Bloecologlcal study of blackfly fenales
3.1 &pcle!1e! !v!ee19 3.1.1 Seasonal varlations of dally counts
Before tackling the study of these varlatlons we would recall the special aspects of the disperslon of S. damnosum females in the Sudanese savanna zone (Le Berre, Balay, Brengues & Coz, L964; Le Berre, 1966): - the disperslon range of females is greatly reduced in the dry season and almost exclusively confined to the woodland vegetation along the watercourses (linear dispersion) ; - at the start of the rainy season, the dispersion extends along the trlbutaries, still remalning essentlally llnear; - in the middle of the rainy season (July to Septenber) the dispersLon of fenales takes on an additional radlated character (ln any direction fron Ehe hatching polnt), especially during days when cloud cover is particularly dense; - the end of the ralny season sees the females return progressively to a llnear type of dLsperslon.
Studies carrled out during the past several years on the rlver network of the Whlte Volta and the Red Volta have shown us that catches of S. damnosr.rm females nere lnterrupted
TABLE 3. CATCHES OF S. DAMNOST'M FEMALES BETWEEN JANUARY AND MAY IN THE FRONTIER AREA
Point D (White Volta) Point F (Red Volta) L966 Average of 4 years Month Half-oonth No. of Females No. of Females I catching caught 7" catchlng caught days per day parous days per day Parous (average ) ( average ) (average )
January First 0 3 20.7 0 45.9 Second 0 7 9.43 2L.3
February Flrst 0 t4 r. 35 L7 .6 Second 4 0. 50 0.0 23 o.57 9.0
March First 15 0 00 60 0. 18 20.o Second 16 0 t2 0.0 64 0. 19 16.6
Apr11 First 15 0. 13 0.0 51 0. 55 41.7 Second 15 0.33 60.0 45 3.3s 63.4
May First 9 29.22 62.0 4t 2L.20 67 .6 Second 7 43.57 60.2 13 L23.20 7 4.O ocP/85. 5 page I 8 aluost everywhere when through-flow ceased, and that this j-nterruPtion then cont,inued throughout a good part of the dry season; nevertheless, this phenomenon is not general, slnce fenales may occasionally be caught throughout the period when the rlvers cease flowing (and consequently when there are no local breedlng sites) ln a strip of land sone 40 km wlde along the frontier with Ghana especially on the banks of the two Volta rivers. Table 3 shows the results of several years of collections roade in thls area (Polnts E and F). Recent blometrlc studies (Le Berre & Balay, in preparation) have demonstrated that the flnales thus caught could not have come from 1ocal breeding sltes (before Ehese disappeared), but euanated from permanent sites on the White Volta Ln northern Ghana. This is indtcative of the flight capaclty of the females, which would be 70 to 80 km under the apparently sooerrhat unfavourable condltions of the dry season and sometirnes 150 to 200 km tiranks to northward advances of the intertropical (monsoon) front (Ovazza, Renard & Balay, L967).
Moreover, when we examine Table 4, we note that the figures for dally catches all peak in August-Septenber after a general rapid rlse following the re-establlshtrent of breedlng sites on the courses of ghe Whlte and Red Voltas irr Upper Volta. The develoPuent of the female populatlon reaches its annual maximum at this tlme; the dal1y catches recorded during this peilod are ln effect only a srnal1 proportion of the total populatlon of females exlstlng at the same moment ln the area by vlrtue of the extent of thelr dlspersion range at that titre (nultlplicatlon of breedlng siEes and radlated dlsperslon). SubsequenEly, the dlsturbances caused Eo the sltes by the rapid fal1 of water level in Septenber have repercusslons on catches, the number oi which decrease more or less abruptly. The renewal of the sites ln Novenber appears at soEe catchlng points (points D and F) as a peak that is sometllttes very oarked. tirl aaffy figures recorded by us at that time at Yakala were the highest of the year. However, as a result of the lintted dispersLon range of fenales at this tlne of the !ear, their poiulatlons are, on Ehe whole, very markedly smaller than what uay be the case in irrg,r"t-S.ptember ln the same area. We may note, furthermore, that the highest number of caiches (1349 fenales per man-day) was noE obtained on the banks of Ehe Whlte Volta but on a trlbutary. This was the largest number so far caught by us in one day anywhere in the east of the Upper Volta. The fact that this maxlnum was obtalned on a trlbutary and not on Ehe uain watercourse 1s not exceptlonal; the highest figures recorded ln the rLver network of the Red Volta also come from collectlon poinEs on the banks of tributaries or in their proxiulty. 3.L.2 Seasonal variatlons of the average sioloelcal age of fema le populations
On exanlning Table 5, we note that the average physlologlcal age of the fenale which is high during populations caught (here lndicated by the percentage-old of parous feoales), itre ratny season, decllnes sharply in the dry season and becomes very low in the hot dry season. The presence of a large majority of nulllparous females in collections made in the hot season, imnedlately before or during the period when flow is lnterrupted, ls characterlstlc of zones of non-pernanent lratercourses (Ovazza, Ovazza & Balay, 1965). In those reglons of the Sudanese savanna ln which there is pernanent rlver flow, the average physiological age of the populatlons of females at thls period of the year ls, on the alnosi invariably raised (Le Berre,1966). In the case of the Volta rivers we "o.rt...y,conslder that the absence or scarclty of parous females here stems logtcally from the absence of any current; gravid females, which are known Eo be selective in the choice of oviposltion slte (Balay, L964), and which fail to find any point conducive to such an operatlon, are probably tla to travel greater distances (increased dispersion), and probably have htgher uortallty due to retentlon of the eggs (Wanson, 1950; Le Berre, L966). From the tlne that flow co-.ences in the bed of the Volla rivers (April to June) the proportlon of Parous females among capEured blackflies become very hlgh at once' generally the hlghest ln the y"aa. Conveisely, these proportlons decrease whenever these flows are subsequently ienporarily interrupted, as does happen on occasion. It therefore seems thatr esPeclally in the'dry the-preience or absLnce of flow near a collection polnt in the area of our work uay""""orr, be a factor havLng considerable bearing on the average physiological age of the feoales caught. It should be stressed that these various asPects of the seasonal changes in the average physiological age of females caught are common to all our catching points located near the maln course of the white Volta and the Red Volta in the terrltory of the upper Volta- ocP/85. 5 Page 1 9
TABLE 4. RESULTS OF FOUR SERIES OF COLLECTIONS OF FEMALES (FRoM MAY T0 THE FoLLoWrNG FEBRUARY)
No. of No. of Date % % Month of No. of Date of No. of collection females Parous parous females Parous females collection females Parous
Polnt A (White Volta) Polnt B (Tributary)
June L8.06.67 32 22 68.7 L6.06.67 0 0
July 06 07 .67 78 77 98.7 05.07 .67 4 3 75.0 22 07 .67 s27 428 8L.2 2L.O7.67 199 54 27.L
August 02.08.67 1 020 313 30.7 01.08. 67 36 3 250 68. 8 19.08. 67 1 180 N.D 18.08.67 1 34 9 N.D
September 22.09.67 436 N. D. 2L.O9 .67 854 N.D
October 06.LO.67 572 N.D 05.10.67 759 N. D.
November 09.11.67 160 98 6L.2 07.10 67 30 19 63.3 25.LL.67 97 N.D 23.LL 67 1 0
December L4.L2. 67 22 7 31.8 73.L2.67 0 0 29.L2. 67 7 3 42.9
January 16.01.68 2 0 0.0 26.01. 68 0 0
Point D (hrhite Volta) Point F (Red Volta)
L2.0s.65 0 0 May 16.05.63 53 43 81 1 25.Os.65 0 0 30.05. 63 2L3 178 83 6
June 09.06. 65 3 3 100.0 13.06. 63 242 2L6 89. 3 23.06. 65 28 22 7 8.6
July 08. 07 . 65 84 51 60 7 04.o7 .63 L32 94 7L.2 22.O7.65 81 70 86 4 19.07.63 394 3t2 79.4
August 06.08. 65 60 46 7 6.6 11 .08. 63 42r LzL 28.7 19.08.65 188 115 6L.2 13.08.63 324 295 91.0 28.08.63 639 453 70.9
02.09 65 96 58 60.4 11.09. 63 L22 105 86 2 Septenber 15.09 65 64 28 43.8 25.09.63 L79 148 82 7 28.O9 65 I 62 t22 7 5.3
October 17. 10. 65 50 29 58.0 09 . 10. 65 103 81 78.5 23. 10. 63 103 63 61.1
Novenber 03.11 .65 L28 45 35 1 05. 11. 63 93 73 78.5 17.11 .65 255 82 32 2 20. 11 . 63 319 L75 54.8 ocP/8s.5 page 20
TASLE 4. RESULTS OF FOUR SERIES OF COLLECTIONS OF FEMALES (FROM MAY TO THE FOLLOI^IING FEBRUARY) (conrinued)
No. of No. of Date of No. of "/" I"lonth Date of No. of parous collection females Parous collection females parous fenales Parous females
03. 13 . 65 77 53 70.1 04.72.63 155 52 33. 5 December 15. 12. 65 22 L2 54.5 18. 12. 63 44 25 56. 8 28.L2.65 11 10 90.9
11. 01. 66 2 2 100 0 03.01.64 9 0 0.0 January 26.O1. 66 2 0 0. 0 L6 .O7.64 3 0 o:o 28. 01. 66 1 0 0. 0 28 .0t.64 0 0
03.o2. 66 1 0 February 0.0 22.02. 66 0 0
Note: The flgures given are the numbers of females or parous fenales captured per nan-day. N.D. = Not dissect.ed.
TABLE 5 SEASONAL VARIATIONS IN THE AVERAGE PHYSIOLOGICAL AGE OF PoPULATTONS 0F FEMALES (PorNTS D, E, F)
Month F M A M JJ A S o ND J
No. of females 36 22 L44 L 529 306 69t L 632 623 256 1 017 675 149 dlssected
Z of parous females 11.1 9.1 59.0 73.5 86.3 76.2 63.r 74.O 67.6 48.7 49 36.2
Seasonal Hot dry Rainy Cold dry percentages of season season season parous feuales L3.4% 79.6i( 47 .82
Note: Aprtl and October are months of transition.
3.2 Dally blting patttern
We sha11 here examine the daily bittng pattern of S. dannosuu females as seen on the banks of watercourses in the vicinlty of larval bre.dlr!-ffiTe shall see subsequently that thls pattern dlffers for parous females as distance from the sites increases. ocP/85.5 page 21
The daily blting pa ttern of S. daonosum females is controlled by two mai,n factors, the age of the fenale and ambient EemperaEure (Le Berrer 1966, pp. 57-68), and influenced by other factors such as cloud cover, wind and rainfall. According to the above-mentloned author: "Nulllparous fenales bite for the greater part later in t.he day than do parous females ... Temperature ls the essential limiting factor ... The upper tolerance threshold for temperature varies wtth the age of the female. The greater the age, the more likely is the fenale to accept high temperatures ... Under some conditions, nulllparous feoales begin to be ln evidence fron the precise moment that temperature faIls".
In order to Lllustrate the seasonal variations in the biting pattern of S. damnosum females In relation to their physiological status (nulliparous or parous) and to temperature, we refer to the results obtained at polnt F on the Red Volta, the only polnt that yielded a sufficlently large collection during the hot dry season to be of use. The vari.ous curves (see Fig. 3) represent the average of several collection days selected during periods ln which the clinatological aspects'specific to the various seasons were very marked, i.e. ln March-April for the hot dry season, in August-Septenber for t.he rainy season, and ln Noverober-December for the cold dry season. We reca11 that these curves are nean curves and that lt sometlmes happens, and quite frequently so, in particular in the rainy season, that a narkedly different curve from ours is obtalned for a collectlon day. These differences are in general due to the lnfluence of accidental and momentary factors such as rainfall, and variations ln cloud cover, as well as in wind strength and directlon. I'le note (Fig. 3) that our observatlons confirm those of Le Berre (see above):
appearance of the mass of nulliparous females at the end of the day especlally after the teroperature fa1ls;
spreading out of catches of parous fenales over the whole of the day, wlth a maximum in the afternoon around I or 2 orclock, except ln the hot dry season when the high evening temperatures shift the appearance of the greater part of the parous females to the end of the afternoon (after teuperature drops) i their curve then becomes very similar to the curve for nulliparous females;
the higher the dally temperature maxlma, the more does the "void" between the two daily peaks (morning and evening) Eend to enlarge and become more marked (Le Berre, L966, p.62). This void, which ls very narked ln all seasons among nulliparous females, ls less marked among parous fenales in the cold dry season and the rainy season.
Because we lacked adequate collections durlng the hot dry season, we were unable to determine whether or not there was a threshold tetrperature above which females ceased to bite. On the other hand we have never recorded catches below L6-L7"C, even in areas in whlch the females rdere plentlful and even lf this temperature was not attained untl1 qulte late in the mornlng (after 8h00 or 8h30). 3.3 Infestatlon bll O1rghocglqe lelyulu! in blackfly In this paragraph, and subsequently in our study, we shall apply the term "lnfested" to parous S. darnnosuu females havlng developlng forms O. volvulus ln the abdonlnal cavlty, the thorax or the head (thus excluding recently ingested nicrofllarlae). The tern "lnfesting" will be applled only to feoales havlng infesting larvae (stage III) ln the head and especially in the mouth parts. 3.3.1 Seasonal variations
We selecEed point D to illustrate these variatlons (see Table 6). There ls close man-vector contact in this locality throughout the year since two villages (Yakala and Foungou) are situated close to the breedlng sites. 0n examinlng Ehis table we note that the rates of infestatlon of females are clearly hlgher ln the ralny season than in the cold dry season. Furthermore, whereas we found one infestlng to two lnfested fenales in the rainy season, this proportion falls to one to three ln the cold dry season. An explanation for these dlfferences rDay be found in the fact that the average physiologlcal age of the populatlons ls, as we lndicated above, clearly lower in the cold dry season. It is also ocPl8s.5 page 22 posslble that, as for S. woodi (Wegesa, L966), the low night-time ternperaEure of the cold dry season ls a factor capable of having a limitlng effect on the developmen t of 0. volvulus ln the insect organism (prolongatlon or lnterruption of the cycle).
TABLE 6. SEASONAL INFESTATION OF FEMALES BY O.VOLVULUS (Point D: Yakala)
Number Percentages
of of of of parous infested infestlng A B c D females females females females
Whole year 1 368 782 72 35 5.3 2.6 9.2 4.5
Cold dry season 518 2L5 10 3 1.9 0.6 4.7 L.4 ( Novenber-January
Ralny season 651 439 53 27 8. 1 4.L Lz.L 6. 1 ( July-Septenber )
[= Infested females x 100 c= Infested fenales x 100 Total of fenales Total of parous females
Infesting fenales x 100 Infesting fenales x 100 g = p = Total of females Total of parous females
Our results for the hot dry season relate only to a smal1 number of females, given the extreme infrequency of catches at that tlme of the year. when we added up the females caught at points E and F between February and August 1966, we obtalned the following results:
Nnmber of females dissected i L28
of whlch parous 75
Nnmber of lnfestlng femalesi 7, amountlng to 9.3% of the parous females and 5.5% of. the total nrrmb€r of females. These rates are clearly higher than those obtalned at point D in the rainy season (Table 4, columns B and D). Wlth the exception of the hot dry season, ln whlch the numbers of fenales caught dally dld not enable us to establish dal1y infestatlon rates, the htghest percentages that we obtalned in the Bissa counEry Irere as follows:
Infested: 26.67. of the parous females on 22/7/65 at point D
2L.8% of the parous females on 02/8/67 at polnt A
2L.5i( of the parous females oa 25/9/68 at point F Infesting: L6.6% of the parous females and 12.3"1 of the total of fenales on 2217 165 at point D
L4.9% of the parous females and 11 .77. of the total of females on 25/9163 at point F
L2.5"1 of the parous females and 7.LZ of the total of females ot l/8/67 at point B. ocP/85. 5 page 23
lle note that all these maxima were obtained in the rainy season; the highest rates relate to point D where, as stated above, man-vector contact is particularly close throughout the period during which the Whlte Volta f1ows. IE follows from all these results taken together that the average potential for transmission of an S. damnosun female population seens to be seven tlues Sreater in the rainy season than during EhE-Ary season and nine times greater in the hot dry season than in the cold dry season.
3.3.2 Daily observaE ions
The distribution of lnfesting bites throughout .Ehe course of the day follows in general the activity pattern of parous females (see Fig. 3). However, it appears, and this is something that should be confirmed by further study, that there is an appreciable reduction in the proportion of parous females possessing infesting forns of O. volvulus between 15 00 and 17 00 hrs. 3.3.3 Other remarks The nunber of lnfesting O.volvulus larvae (found in the head of the insect) varies between 1 and 8 for all fenales dissected; onLy 25% of the infesting females were found to have two or Dore infesting stages rrith this locallzatlon at the same time. The nuober of thoracic fonns (lnfesting larvae, stages II and III, or sausage forns) per female ranged between 1 and 9. 3.4 Variations in the populations of blackfly feoales as a function of distance from breedlng sltes
Series of collections made on the Red Volta simultaneously at point F (on the line of breedlng sltes) and 6 ko to the rilest of that line, confirmed by a later study hlgher upstrean (Balay, Rolland, Remy and Le Berre, in preparation), showed that, as the distance from the llnes of breeding sites lncreases (results obtalned in the ralny season): the nuober of catches (a11 fenales) generally decreases progressively; the average age of the female populations fal1s very appreciably and very regularly (642 of parous females at point F as against 37.8% at a polnt 6 kn away from the river ) I whereas the ratlo of infest.ed parous females appear to vary 1itt1e, those of lnfestlng females decline appreciably (7.5% parous at point F as against 4"1 6 kn away). Thls phenooenon, taken in conjunction r,rith the preceding one, has the effect that the capacity of S.damnosum to effect transuission appears to be approximately four times greater in this area along the line of the breeding sites than at a dlstance of 6 kn from that line; the reduction ln Ehe ratio of parous infesting females between 15 00 and 17 00 hrs would appear to be urore pronounced far from the breeding sltes than close to then; the datly biting pattern also differs appreciably; if we consider the curves in Fig. 4, which were plotEed on the basi.s of the average fron 5 days of collection ln the rainy season carried out si.multaneously along the line of breedlng sites (point F) and 6 krn fron that llne, we note that whereas the two curves for nulllparous females are practically Ldentical, the curves for parous feroales differ, that obtained at a dlstance fron the breeding sites being very sinilar to the curves for nulliparous females. ocP/85.5 page 24
3.5 Srud of the transmission of onchocerclasis
There is considerable variation every year in the contact between man and the vector (in duration, extenE and nature) in t.he area covered by the present study owing to seasonal variations in the distribution of the breeding sites, in the type and range of dispersion of the feroales and in their potential for transmission. In this set of factors, the seasonal movements of a proportion of che human population towards the watercourses (bush cultivation ln the rainy season, fishing ln the dry season), have only a uinimal overall influence. On the other hand, at the local 1eve1, on the scale of the village and above all of the family, they noay have a bearing on the extent and severity of the disease (Balay, Rolland, Reroy and Le Berre, in preparation), Table 7 reflects the seasonal dlstribution of t.he transmisslon of oochocerciasis (perlod and extent) in relation to the various collection points.
In February, March and April (times at which flows are j.nterrupted), Eransmission seems to be non-existent or at least extremely low. It affects only an insignificant proportion of the Bissa population, and only ln the south of the country, essentially the infrequent villages or fisherments camps along the courses of the White and Red Voltas. For the most part, transmlssion occurs during the rainy season. In effect, according to table 7, we find that the period May-Septerober inclusive accounts for 692 of total annual transnission at point D and 8LZ at point F. At the local 1evel and overaIl, the maxj.num flgures for transmlssion are almost invariably reached in August-Septenber. At that Eine, consldering the proliferatlon of breedlng sites and the appearance of radiated dispersion of the females, rre are of the opinion Ehat no village in t.he Bissa country is completely exempE from an lnfesting bice. Consquently, the proportion of the human population liable to have had contact rdlth the vecEor is conslderable.
In general, transmi.ssion in the cold, dry season (November-January) seens to be much less inportant; it only affects an increaslngly reduced human population insofar as the females return to a linear disperslon range, confined to the bank areas of the najor watercourses. From December onwards, the only human groups that nay be concerned are those llving along the banks of the Volta Rivers (the villages of the Niagho and Yakala regions in particular, flshermen). At the 1ocal level, relatively hlgh figures for catches may be recorded aE this tlme (255 females per man-day at point D for exanple), but these are females whose transmlssion potential remalns low by comparlson wlth the rest of the year, as we have stated previously.
We nay also note that, in general, the periods during which transuission can take place are j.ncreasingly short as one ascends the Volta Rivers from the lower to the higher reaches or moves away frorn then (varying fron one year at points F and E to a few weeks for some vlllages at a trlbutary head). It is, Eoreover, lnteresting t.o note that some villages several kiloneters fron the Volta Rivers (the case of Niarba, polnt B, in particular) may be subjected to appreclable masses of bites for some nonths of the rainy season (5 nonths in this particular case); the masses of bites may be as great, lf not great.er, than those received by some bank vlllages of the Volta Rivers during a narkedly longer period (8-10 months). The presence of such quantltles of females, far frou the main course of the Volta Rivers suggests that a large proportlon of then come from habitats of the tributaries (Koulip616 in the case of Niarba). lrle are of the opinion that the tributarles play a role that may be more important than that of the Volta ltself in the diffuslon and distrlbution of onchocerciasls, at least in the river network of the Whlte Volta, between polnts A and D.
The sane hypothesis was put forward by Ovazza (1956) following a tour ln this area.* * Thl" hypot,hesis was aroply verified by a survey of an area of the Red Volta: Sechan (1968): Etude d'une populatlon de Simullum damnostrm Th. dans la r€gion de Nob6r6-Donsin sur 1a Kouroumba (Haute-Volta). (Rapport Centre Muraz No. 219/0ncho, 9 pages) ocPi85.5 page 25
F\ r\ o\ Fl FI .f \o o o F- (H @ o\ o @ o c.l .r.t < (\l rn (f) \? o\ rn N ! D<'-1 tn 0) .(, Or+{ z? c o\ @ o @ \? -{ zo Fl r{ .f (7) tr >t+{
4.L Parasites of S. daronosum females
Most of the parasites of S. damnosum females described by Lewis (1953) were found in the course of three dissectlons: Mermis spp., parasitic nenatodes of the Malpighian tubules, hynenopteran larvae, gregar inef-aiZ_c i lia te s . 4.2 Other species of Sinuliidae
In addition to S. damnosum the followi ng speci.es were collected: 4.2.L fn preio"gl"al habi (breeding sites)
S. adersl Pomeroy S. ruficorne Macquart S. unicornutum Pomeroy il66ETEt'Ie-i11on s. seicolle typical form Becker S. griseicolle, tridens forn Freeman & de Meillon S. schoutedeni Wanson S. meduseforme hargreavesi, form Gibbins S. alcocki typical form Poneroy S. coc djallonense, form Roubaud & Grenier S. alcocki occldentale form Freeman & de Meillon
4.2.2 Collected by huoan bait
At the height of the rainy season we noE.ed the capture of occasional S. adersi and S. bovis females on human bait. Some of these feoales had taken blood r".I[-th" aiilnr-opoptrilion of these species has previously been reported by several authors. "hance OC Pl85.5 page 27
CHAPTER III - ONCHOCERCIASIS 1. Background information The Bissa focus i.s one of the oldest known foci of onchocerciasis in West Africa. It was in 1939 that Richet flrst described onchocerciasis in the Bissa country in an arEi.cle entitled "lt0nchocercose afrlcaine ou volvul-ose". However, no overall idea of the extent of the infestatlon was available until the mass survey in 1948-1949 by Puyuelo, of 102 188 persons, including 59 270 in the cantons of the l^Ihite Volta. In 1957 the ophthafunologlsts Veui.lleux, 1e Breton-Oliveau and Aubry made a cllnlcal, parasitological and ophthalmological examinatlon of 34 170 indtviduals in 150 villages.
Because the Bissa focus was revealed as one of Ehe largest foci in West Africa, there were many subsequent surveys lncluding those of Lagraulet and Anman in 1960-1961, Monjusiau (L962-I964) and Lauontellerle (L963-1964). gne of the present authors (A. Rolland) also studled onchocerclasis in the Bissa country betlreen 1958 and 1960 as Chlef Medical Officer of the Tenkodogo cercle and between 1966 and 1968 as Chief Medical Officer of the nobile ophthalmological group of the Upper Volta Rural Health Directorate. 2. Clinical st 2.L ExtenE of the disease Fron 1963 onward, the prospecElng teams of the Department, of Major Enderoic Dlseases, followed by the Rural Health Department of Upper Volta, have been detecting persons wlth nodules frorn village to village ln the Bissa focus and elsewhere ln the country. The following results have been obtained for the main Blssa cantons. For the whole of the Bissa country vre arrive at a figure of 17.6% of Ehe populatlon presentlng onchocercal nodules. However, such individuals are only a ProPortion of the sufferers fron onchocerciasls. If we accept that persons in whom dermal ulcrofilariae may be detected by skin snip are sufferers from onchocerclasls, their number nay be aPProxinately determlned by nultiplying by 2.5 the number of individuals having nodules (thls coefflcient rdas arrived at fron parasltological surveys conducted on several thousand individuals ln the area).
Consequently, the number of carriers of Onchocerca volvulus rnlcrofilarlae maybe estlmated at 447. of the total population, which would correspond for a tot.al of 200 000 inhabitants to ln all 88 000 sufferers. An addltlonal number of onchocercal patients could ln fact be detected by other methods (serologicaJ- - l(azzotti test). It ls therefore almost lmpossible to deternlne precisely the total number; sufflce it to say that more than half the lnhabitants of the area suffer to some extent from onchocerciasis. 2.2 Distrlbution of the disease fhe village by village detectlon of individual carriers having nodules enables us to plot the distribution of the dlsease in the Bissa country.
The villages have been classified into three categories:
(1) vlllages in which the dlsease is hypoendemic and in which there are less than L27" of tndividuals wlth nodules;
(2) mesoendemic villages with 12-21.9% of. individuals having nodules; ocP/85.5 Page 28
(3) hyperendenic vlllages with nore than 222 of indivlduals having nodules.
We obtained the following results: (1) no village in the Bissa country is free of onchocerciasis; (2) the villages most affecEed by the disease are obviously the villages closest to Simuliun damnosum breed ing sites; (3) in the restricted, sparsely populated areas enclosed between tr4lo rivers, rich in S. damnosum breedi ng sites, practically all the villages are hyperendemic i.e.:
- the Tanema area between the White Volta and the Dougoula Mondi; - the Niarba and Niagho area beLween the White Vo1ta, the Kou1ip616 and the Silmisilido; - the Zabr6. area between the l{hite Volta and the Red Volta; - the area between the White Volta and the Noahou. (4) In areas where population density is high, on the other hand (Garango, the area said to be that of the Yeribas betlreen Gomboussougou and Zabr€, and Yargantenga) lnfestatlon decreases regularly as distance from watercourses with S. damnosum increases. 2.3 Serlousness of the disease This was investigated at the ocular and general 1eve1s in the selected villages.
2.3.1 Selec tion of villases
We chose nine villages on the basls of their location in relation to the 1arva1 breeding s ites Proceeding uPStream, we examined:
(a) In the Zabr6. Canton, three villages located either in direct proximity to breeding sites (Yakala), or bordering on the depopulated zone (Zarparia Zabr€ towards the Red Vo1ta, Sambaregou towards the tr{hite Volta). These we refer to as first line vi11ages. hte also exanined one village located within the inhabited zone between the White Volta and the Red Vo1ta, Boka Zourma (second line village). (b) In the Canton of Niaogho (Garango cercle), we exauined two vl11ages close to important breeding sites on the White Volta or its t.ributaries (Tigr6 and Niarba) and, in addition, a part of the village of Niaogho, which is practically on the White Vo1ta, but in a zorte with very few breeding sites of S. dannosum.
(c) Lastly, we exami-ned the Zatga quarter (third line vlllage) within the Garango zone, where population density is high. Our survey thus covered nine villages and L264 inhabitants.
2.3.2 Examination method (a) ParaslEological examination
Two skin snips were taken from all inhabitants of the village (one on the shoulder, the other on the iliac crest) and examined when fresh for Ehe pres ence of O. volvulus nlcrofilariae.
(b) Ophtha1roological examination
The purpose of the exarnination was essentially to detect lesions. In all Persons more than four years o1d infected bY Onchocerca we examined the anterior segment by slit larop and the fundus oculi by direct ophthalmoscope. ocP/85. 5 Page 29
As regards ocular function, we contented ourselves with recording those individuals who could not see fingers at two metres, whom we regard as blind. Recording the results
The age-groups adopted were: 0- lyear 1 - 4 years 5 - 9 years 10 - 14 years 75 - 29 years 30 and over. Individuals exhibiting ocular lesions were classified as follows: (1) sufferers from punctate keratltls alone; (2) sufferers from punctate keratitis in association with the presence of microfilariae in the anterior chamber of the eye (MFCA); (3) sufferers nerely having microfilariae ln the anterior chamber (MFCA); (4) sufferers with typical iridocyclitis; (5) sufferers from sclerosing keratitis; (6) sufferers from chorloretlnal pseudodegeneration (nottled, tigroid or Rldleyrs pseudopigmentary degenerat lon) . PaEients in groups 4, 5 and 6 have in most cases other assoclated onchocercal lesions (punctate keratitis, MFCA, associatlon of scleroslng keratitis and iridocyclttts), but they are defined in our tables according to their most developed lesions.
The sufferers from ocular leslons thus defined are next grouped into three tyPes (Ir IIt III) by the severity of t.he lesions: (1) sufferers from punctate keratitis, in whom only the cornea shows slgns of the passage of mlcrofilarlae, and sight is not affected, are classifled in type I; (2) type II incorporaEes patients in whom punctate keratitls is associated wlth I{FCA or in whon MFCA is present alone; the nlcrofilariae have crossed the sclerocorneal barrier and are established inside the eye; slght is not yet affected; (3) patients of type III suffer fron developed lesions of the cornea, the iris, the choroid and the retina that threaten the eyesight (sclerosing keratitls, iridocyclitis, chorioretinal pseudodegeneratlon) .
The results of the parasitological and ocular examLnatlons categorized in this way are reproduced in the tables, which constitute a complete "onchocerclasls" file for each village examined. (c) General exaoination
The working methods and the results will be dealt with in a following sectlon: General complications of onchocerci.asis. Pathologlcal associations. ocP/8s. s Page 30
TABLE 8. DISTRIBUTION OF ONCHOCERCIASIS SUFFERERS WITH NODULES CARRIERS BY CANTON
Individuals Individuals Cercle CanEon Persons seen with with nodules as nodules % of persons seen
BEgu6do 3193 279 8.7 3 Boussouma 53 74 427 7 .83 Garango L27 94 T T28 8. 81 Lengha 2 327 87L 37 .4 GARANGO Niaogho 5 888 L 487 25.2 Gouboungou 3 75L 368 9.8 Sanogho 10 249 1 559 L5.2 Komtoega 6 L20 1 111 18. 15
Ban6 77 69 1 s66 20.t TENKODOGO Zoangha 68 04 458 6.7 Yargatenga 57 62 663 11.5
Zabr6. 30 517 I 223 26 Gouboungou 8 968 7 283 L4 Zourma I 810 311 t7 Yakala 2 8t5 776 24
Total L74 44t 20 244 L7 .6
3. Epldeniology of ocular compllcations
The villages examined have been grouped as follows:
(1) first-llne villages located close to S. damnosum breeding sites or just outside the depopulated zone (124 vll1ages);
(2) second-Iine villages at some distance from the flrst (86 villages); (3) third-llne villages deep into the cultivated area (76 villages).
3.1 FLrst-line villages (Tigr6, Niarba, Yakala, Foungou, Zar paria, Sambaregou), 772 of. whose lnhabitants are Lnfected wlth Onchocerca. The distribution of persons infected by Onchocerca is as follows , by age-group:
0 - 4 yearsi 7% infected 5- 9years: 33z. infected 10 - 14 years | 887" lnfected 15 - 29 years: 917" lnfected 30 years and over: 927" infected. Of the total population, 7.6% are blind as a result of onchocerciasis.
Out of every 100 individuals infected by Onchocerca: 14 have slight eye disorders (stage I); 25 have the parasite within the eye and are likely to have ocular complications (stage II); 20 have severe irreversible ocular lesions (stage III) and 10 of them are blind. ocP/8s. s
Page 3 1
The eye disorders are unequally distributed by agei they are more frequent, and, above all, more serious as the age of the individuals increases. Slight disorders (stage I and stage II) affect 307. of persons infected by Onchocerca in the 5-9 year age-grouP and 502 of thoie in the 10-14 year age-group. Serious eye disorders begin to appear from the age of 15; our records show L4Z of. serious eye disorders between the age of 15 and 29, vith 5Z b1ind, and 32'l of serious eye disorders and 22% bLirtd at age 30 and over.
3.2 Second -1ine villaees (Niaogho, Beki, Zourma) Fifty four per cent. of the inhabitants are infected by Onchocerca.
The distribution by age-group is as follows: 0 - 4 years: L.57" infected 5 - 9 years: 18 7" infected 10 - 14 years: 322 infected L5 - 29 years: 85 7. infected 30 years and over: 87z. infected Above the age of 15, the percentage of persons infected by Onchocerca ls the same as that found in first-line villages, but below Ehe age of 15 it becomes less lmPortant: O.8% of the total population 1s blind on account of onchocerclasls. Out of every 100 persons infected by Onchocerca in this group: 18 suffer exclusi.vely from eye disorders (stage I); 11 are in stage II; 5 have serious eye disorders (sEage III); 3 are blind. Similarly, rhe age at which ocular lesions appear increases. Stage II leslons do uot appear untll age 15 and 1ater, and severe lesions and cases of blindness due to onchocerciasis are not found until age 30 or o1der, with the following percentages: 7.L% for stage III lesions and 2% for cases of blindness. 3.3 Third-line village
The percentage of persons infected by 0nchocerca renains hi.gh (402), but the rate of ocular conpllcations i.s further reduced. Most sufferers frou ocular leslons have benign lesions, and the age at which they appear has increased (15 years as against five years in the other villages). The two Patients with severe ocular lesions are patienEs who came froo abandoned first-line vi11ages. Thus, it is the location of the village in relation to breeding sites of the vecEor that deternines the severlty of the disease. The percentage of blind persons and of serLous eye disorders is very high, even catastrophic in first-line villages, for the age-groups over the age of 30. On the other hand, as distance increases, severe ocular cotrplictions and cases of blindness caused by the parasltes remain fairly infrequent (32 of the total of persons infected by Onchocerca) , although the percentages of persons infected and of benlgn ocular conplications remaln relatively high.
Those individuals who have ocular lesions are often agricultural workers who farmed in first-line zones.
4. Sex distribution of eye dlsorders
Whereas the number of persons infected by Onchocerca is about the same in both sexes (75.47" of the men examined in the first-line villages and 73.5"1 of the vonen), the situation is qulte different regarding eye disorders. In thls same group of vil1ages, 9.72 of the rnale inhabitants are blind as a result of onchocerciasi.s, as agai,nst 5.12 of the $romen. The reason for this is that women are in general less often in contact with the blackfly vector than are men, owing to the divlsion of agricultural labour (see Tables 1 and 2). ocP/85. 5 Page 32
TABLE 9. SEVERITY OF OCULAR LESIONS IN PERSONS INFECTED BY ONCHOCERCA (CLASSIFIED IN THREE STAGES) IN FIRST-LINE, SECOND-LINE AND THIRD-LINE VILLAGES (PERCENTAGES )
Total of Persons with onchocercal ocular lesions Total persons infected blind by 0nchocerca Stage I Stage II Stage III
Flrst-line village 100 L4 25 20 10 (rate of infestation 77%)
Second-line vlllage 100 18 11 5 3 (rate of lnfestatlot 54%)
Thlrd-llne v11lage 100 27 2.5 5 2.5 (rate of infestation 4O7.)
TABLE 10. DISTRIBUTION OF ONCHOCERCIASIS AND EYE DISORDERS OCCASIONED BY oNcHocERcIASIS By AGE-GROUP, IN RELATION TO THE LOCATION OF THE VILLAGE RELATIVE TO S. DA},INOSW BREEDING SITES
First-Iine vlllage Second-line v11lage Third-llne village
Ex O+Sr I Sr II St IIIAv Ex 0+St I St II St III Av Ex 0+St I St II St IIIAv
v4 101 7 66 1 22
5-9 93 31 11 2 4382 25 1
10-14 75 66 22 L4 I 46 15 8 27 I
L5-29 224 205 35 65 29 11 6L 52 11 3 2 18105
30 + 266 257 15 66 84 47 L26 LLo 13 18 93662861 2 1
Total 759 566 83 L47 114 58 342 L86 34 2L 11 3 158 40 11 I 2 1
Z Ex 100 74 7.6 L00 54 0.8 100 25 0.6
7" O + 100 L4 25 20 10 100 18 11 53 100 27 2.5 5 2.5 ocP/ 85. 5 page 33
h N e.t o o ! o o CN co E ! ]J FI .Ft .{ FI ! 'N o o fq .+ -? | '-l ?, oo c, ,c(! e{ o\ F{ q O'rl F{ d tro C) ok c.l N o o
I o I ..{ 14 .f, \t Ou oH H lrtr r-l o\ o & O"i -{ Fr ()C,l.Cr) U' F{ r^ \o H tr a rlt
H H o h F-{ FI H lF{ H H OrJ fr E 'r{ 6t (r) t< o .Fi .{ @ !o tn (d Hh c{ c\,1 -f H u o z .-. a HPt o =i F QE o @ .Ft tro h FI v) .F{ i -{ *9 o u}u Ya F{ O +.1 F{ .+ rn a< lf! a(J l] o.! $ F{! E F{ (r) .+ til FI oo 'EI ) a:z o z2 o UE ;(J h rl cr') \, co +J .r{ 3e () B F{ c.l @ o\ o tr]t h 6t @ E F( r,r tr H E GI ttl rn e.l o H o ,l tr o o @ Hd=3 A r0 o A> arJ UU .ootrc! ..; .rl o fq FI cr) CO \o o\ e{ F{ O lr F{ a.l rn !lJ() f.I o u xo N (f) .+ r\ @ \? o o! o .$ t.rl (n Fl aJ -t -t EA '+{ -C F..t otr o A r{ o FI FI o\ 6,t A.-l F{ H ot Fl CN N @ fq F\ $ $ F\ o ct dto(u F{ (n \o O '.1 Fl o ltl o o \o oa (\ e.l -l rn \o \o lr r! FI ox \? \o r-{ (Y) o .+ FrO F-{ r-t Fl (n (f) o F{ o th o. lr lr o o (! (d o t{ ! o o tt, tr (0 d x x lr @ o o (! I x x \t o\ o FI 0) Fl N >\ (d @ -f o\ I I rJ I I o I^ o o o n FI r-l CO H ocP/85.5 Page 34 tr (n o o L o o (Y') (n c t r) a o E pFI r+{ o v, fq Fl (r) .f lFl o oq) o .c(! .+ @ ct o Or{ F{ d tro () Orl E (v) @ o o o I"{ t\ (n tn co Ot, +.,lr{tr il o o o Or{ F{ Fl N !, oo)-C E r\ r.t 6l ! F{ I frl ().1 H o fq N r{ (n & H l+{ ,{ H orl o td N (n n o r{ F{ o @ t{ c, (9 (, HX E N N z u o U) S,,l o F 3I o o0 QO k lu, o rld o r,L) .f F{ O+{ 6l \o lru QE k o(0 2n (! Fl I{ E 6l .f \o F{ oo 3X ut .y o Ho^c) o XCJ .c ft. N .$ .if o rJ F{ <1Hv ..{ B (, N r\ r\ \o zl fi FI o ('t I rrl tr H = E (n \o o H gE (,, dH lr o o, @ A{ d o t, O, r{ fr F{ .$ .s o\ E! U) +JrJ< 6+{C) ri ura 6t \o -$ 6l rE o (0E F{ trk (n (rt'I + , o+ E F{ N {5-r. AJA EF\d >lr ttt H O fq d F{ N tJu'r{ o tU ''{ @ TJ TJ 6t 6t tt1 F{ o d or! F{ .i +J trtr FI U' ,@ E N N .i @ E] a,! Fl la tr(6 H €o o h (Y) r\ N N .J. Or{ t{ N 6l tn +JrJ o o o xo (n t\ r\ N .t cr) o op o Fl .f (Y) o lrq E FI otr o (") .f o o cl o\ F{ .f O-l oA F{ 6l t la \o r\ N 6l N oo N N \o ctr o\ (n co 6l \o co Ot{ .s (7) oa F{ Fl F.i N lro F{ ox E (r) @ Fl o .f \o OiO A F.l N F.{ \o @ art A H ! a o (,, (! (U o lr t{ o o o ! (0 (0 h x H oo o o) ru I >i .+ o\ 0, F{ o FI 6l >' q, .f I ! @ c I rn I I o (tlo o o rn F{ F.l H ocP/ 85 . 5 Page 35 (t fr @ tr 0,) 0, F.{ c.t c -{ € U .rtc o A FI Fi 6t pr-t t! o U) h 6l a-l I ..{ q oo o -c(! r-{ o\ o o O 'r{ Fl (0 tro () Of. E FI N 6 o o U) I .-l k c.l c{ Orr .F{ .F.l litr Fl T\ o\ O .F{ -{ Ep (-)o t F{ r^ F\ tr -{ I rd F] H tt Fq C) H I .ri il H OU El t'r{ cl Fl (n C) o .r{ r-{ @ lrO f:I d H>\ 6l F{ (') & a..J o 3H o NH a r o @ I .d FO fr Fl ,-{ a U) 'H ..1 2H o thJd o(/J r-.{ O ..{ tn rn ts< !lJ ZH l] o(6 14 @ \o (aC)! \o \f \o o r.l F{ rn o ..{ o\ N 6 o oa F{ Fi c-l (n o lrd .-t OX N c') \o 6 o pr c) Fl Fi n o o a lr tr o U) (0 (! o tr lr c) o o tr 6 x x l] @ 0,) (u o I x x $ cl\ o r.{ o Fl c\.1 x (! oo \t c'\ I I rJ I I o ln o o rn r-{ Ft (f) Fr 0cP/85.5 paSe 36 h o o ! o o F{ ...{ d t U F Fl Fl ..{ o E pF.l qr o tt, frr FI Fi I ..{ th Oo o -c6 FI 6t c7) 6 U '.{ I (u tro (.) Olr .-{ Fl (\t o EI o c)'J & vt I fq F{ ();d O+,'.{ -l r{ t{ rr1 lrtr Fl 6l .i d Or{ FC EU c)o E .-{ e.l (n N tr I z qt o H f{ F{ 4 F{ H I '.{ z H ou € 'r{ -{ 6t (",1 o o Fi Fi @ lr (J (0 Hh F{ F{ 6l .I r, (, < rrl u) Vrf o h .f, .f tt, th l{ o o .s \s t o+J F{ ! l+{ o U) F.{ (r) .$ I tq o OU,'r'l o .c(! SI 6t $ (t) O 'r{ F{ FI (0 Cc) Q Orl E r-{ o\ o o FI I o z U) o | '.{ h FI (n .i H OIJ z .r{ ..{ r{tr N N o\ C) O'.1 fr] -C tJ & ()o F.{ .f !n a tr = N H o h F{ F{ H H I 'r'l a H Ou t) t"i \o \o (u .F{ F{ @ !o 14 (0 H>r E tn tn E u o tq U) o tr o @ 'r{ fr N N o Co 3F o ou zP od rf) l^ -{ lrrJ fls ! 0r6 tA. (u F.{ H (v) (Y) q{ ^ Fl oo a @,9 5H o ex o fq rn rr1 o dP r] F.l 8ts ..1 :.; o B C) \o o\ t.! h F{ U' E 3e a H E FI \? rn o H t) So: ! o o @ dH A{ (0 (n EE aU {JU q) o lrUt k 5 o o (u 6 o t l. o o o lr (u o x >\ t @ o o (! I x h -f, o\ o F{ o F{ C\ .J. h rd @ o\ I I u I I o rn o o o rn F{ Fl (7) H ocP/8s.5 38 Page k F{ FI oCD ! o o 6l 6l t rJ tr o E F{ FI 'F{ FI ! t.|{ o th h (7') (7) lil o oo o t6 F{ r\ @ (tt O+{ d tro o Orl E F{ .f o o o I ..{ fq N N Ou r.tr N \o co O '.1 .C Lt C)o E 6t .{l \o I lJ rd ().l l-{ o E .+ .$ & H lr{ trl H O!, o El t{ o\ o\ o +l Fl frl @ trO il (6 rt\ Fq H>, E Sg aIJ o to o @ 'il Q@ E oCN g}rj V* Ft F{ -, U) F{ O+{ N lr fJ t{ o(0 s3 (0 F{ F{ N '-{oo ll -ta a.y s# o EE o N6 h F{ FI ..i tz ("'t B o FI N fr !r o E tr H E F.{ N Hu o H '-{ gi o !a Fi l. c, o 6I, (U A o .5' IJ Or{ fr. (\l N 3E lJrJ< v) (!r{() U (v) (n \o rE !, (!Efr. tr}{o r{t' , o+ E F{ F{ N {il oiJ 'id iFIr .D >) t-{ Or{ k o\ (t'l 6l +JU F{ o q,t{ ?.{ l/1 o\ @ rJrJ ..t N (\l \o (6 OG N Fl TJ trrl a F{ N N N N a0) E r{ F.l EI P{J .l Fq tr(! t{ F{ F{ to o h N F{ r\ O Fi li F{ (n ln }J!J O o o ho .+ @ o\ @ o\ o op o (Y) tn o u r+{ .c ri N N N co otr o E r\ rn Or{ ot 6t 6t Ir o\ o\ \o (r) N CN (,,oo cl ('t t\ da @ \o o?{ @ o .fn t1 OE FI 6l F{ f{6 F{ ox c FI o\ N \o AO F.l N 6l N o o A F H a att (t 6 o o k o o o tr ,r 6 h >\ lr @ (U o (, I o >t .f o\ o -{ o h -{ N >\ (, .+ I ri @ Ch I tn I I o (no o o tn F{ FI Ei ocP/ 8s. 5 Page 39 h FI .-t o (t) lr (ft o 0, c') c .du t N (\l ..itr o rip tH o Eq o I .'{ IJ' Ou) o ,<(0 F{ F{ (t) O (! tro'r{ (J Orr E FI FI o o o I .'.{ h -t F{ O}J .F{ .H frtr N N O ErJ'i{ (,o E -{ FI t{ J FT C) & H q h frl H I ..{ o H OU 'r, .H frl o .F.t Ft & @ trO tq (! Hh E *s au o ID o @ 'E .r{ FO fq 6 .rl ."{ 6s o ou .r{ F{ o r..l -{ !l, vc)E3 tr o(! (U Fl lr r{ FI F{ oo Hfr a @)l o 38 o .c fq ,o,z IJ rl () N 6t Sr , h o *u tr H = c\.1 6l o H H3 o H o OJ o0 Ar (0 o #! .J Otl fa Fet,l ar.) U]J< cn ..1 (J FI ri r)rJfq(UE TE tr}Jo tlI o+ r.{ F{ A{l, <64() o H O t\ (n .'f !H UtJ'.{ o t0 '.i 00 UU Fi F{ Ln F\ (d o(! F\ u trlr r{ (n aa E F{ c.l (7) A{J El FI co d(u H to o h c'\ r\ \o O ..{ tr (\l (7) rJ.J O u o xo .-t N o\ \' \o o op o r{ rrl F\ +J qr -d o F-i c-l ()..{otr o r\ o od F{ 6l .$ E h -t N @ rn \o rn o0) r-t FJ F{ (a @ ct O".{ N (') (7) @ \o C! oe (n N c\ (\I \o F\ rr(U .-t OX z co Fi tt'l cr) o F. A0) -i -t -i FI (7) @ @ (n o. tr lr (r, (t) (u d o lr ! 0) o) ah tl r! (d x x tl @ o 0,) I x >\ -$ o\ OJ Fi o Fi 6l h (0 @ .$ c I I r, I I o rn o o o tt) -t Fi (7) H ocP/85.5 Page 40 o 14 o tr o o tr o oTJ .F{ Fl E t+{ o o h F.{ I ..{ o oo o 6t c{ o -q(! (! trUOt{ (J Otr E FI FI o I o l! @ g I ..{ F{ N -? \o ..1OrJ .d Bs lrtr 6t F. O+{ Eu HE (.)c) FI FI F{ qt t 5g-H H o h H I n{ ig H OIJ HE € 'r{ o Fl F{ (99 @ tro (0 H>, E Eg ! o U) o 36 t 6l t o @ +{ Qo h 7g o 0, OU F{ Or{ F{ F{ oi lrrJ lr o(6 (u F{! Fl F{ EE F1 oo a ax o E= o lk F{ @ o\ a)- rJ B (.) F{ o\ 46 fr ,{o o E EH H F{ r-l 4v) o H rql o lr o) o 00 B r,I A. (! o 2i arr rr! o u, A li t a o o rd (0 o l{ tr (u o tt, l{ (d .! >r x l{ @ o o (U I >\ h .$ o\ o F{ o -{ N h (0 o0 *, o\ I I U I I o o o o F{ F{ (f) H ocP/ 85 . 5 Page 4l fq -{ F.{ U' o tl o cl C\ N tr t {J tr o E Fl F{ 'r'l !F.{ t+{ o o t\ FI I 'r{ I o Oo o .cd F{ F{ att O+{ E] (0 C) () Otitro H o il o ats H o o | '.{ h rd oU..{ Fllrtr H Ori F{ .cu(Jo d t{ = aF{ zH H H th fri 6l N H lil H e .Oo! ..{ N N o .F{ Fl (Jo @ trO z d Hh E atl o Se ttt d 3E o @ Y{ lo h lu) at) F{ ..{ o.) ou 7.a F{ O r.| lrU H< ! o(0 (0 Fr! FI oo 72 ttt .y o o9 o a<) r{ F.t u r il ()l*3 B () FI F{ h (o lpt a H o H ^(2 tt Ertea tr o t-{ H o, @ O{ (! o gE rJ od fq (/) {Jrr< t-g rB+{() rJ!fa oF1 o (dE L'H trli, o+ 3b Orl (Jrlatr vF t, H 14 N rl r\ uuO "{ o o t0 '.{ z @ rJrJ t/) \o FI o o(! F{ ! trr. N u) ao E (n Fi .i AJ oE{ ()El tr.u !o o t\ (n @ ,{ Fl O.H t "{ 6l ,-l r]u o H O O >rO Fl r-{ o @ o o op o F.l N -f r, t4,{ .c o6 (J E -t Fi N o c O-l ot F{ F{ "iFl (') F{ \o o\ 1I1 t fq sl r\ FI oo Fl .-l r{ (f) r\ ca dt O '.1 6t r\ @ \o @ OE sl e{ 6,1 .{ \o !n Fi lr(0 FI OX E o N \o r-l o o\ aq) Fl FI FI FI (Y) r\ o o A lr lr a v) o (U (u o t{ ! (l, o o tr (! (0 x x tr @ @ o (! I >l >' .+ o\ o) -{ 0, Fl e{ >r 6 @ .$ o\ I I rJ I I rn o o o (v) o tn F{ r{ H ocP/85. 5 Page 42 5. General complications of lnetleeereig€iq_: Pathological associations Whereas lt is conceded that onchocerciasis results in serious ocular conplications, the general conplications of thLs parasitosls are far less known. It ls, howeverr lnpossible to study a focus of onchocerciasis without attenpting to specify the effect of the disease on the general health status of the people and to list. the pathological associatlons Dost frequently encountered. To that end: (1) ne sha1l set out lnfornation on the main epidemlc and endemo-epidemic diseases of the Blssa focus gleaned from medical adninistrative archlves and from the results of previous surveys; (2) we shall give the results of our own personal surveys. 5.1 Endeooepldemic dlseases of the Bissa focus Sources: Adminlstrative archives of the Tenkodogo cercle (fron 1930 to 1958) Medlcal archives of the Rural Health Departnent (fron 1931) (1) Measles concerns only children; it ls unlfornly distributed throughout the country. (2) Snallpox: two epLdemics are referred to in these archives, one in 1947 (545 cases), the oEher ln 1948 (239 cases). (3) Cerebrosplnal neningitis, which was reported in 1930, became very serlous between 1946 and 1951 (7L25 cases for the whole of the foroer Tenkodogo cercle, wlth 152 of deaths), and between 1955 and L960 (5725 cases during the period 1955 to 1958, with a peak of 3805 cases in 1956). The whole of the country was uniformly affected, both the northern cantons (Garango, Kouto6ga, Niaogho) and the southern cantons (Zabr6, Yargatenga). (4) Has t.rypanosomiasis been a serious dlsease ln the Bissa country, especially ln the abandoned areas? It would appear, ln fact, that the index of contauinatlon has been relatively low. In 1936-1938, Richet detected and treated an lmportant focus at ZLd'rE (Garango tercle), and in the sma1l vlllages along the Dougoula Mondi in the north of Konto6ga and Garango (Tabs6, Soutaya, Malenga) (roughly 150 cases). Systenatic ProsPecting for the whole of the Tenkodogo cercle (the Bissa country and the Mossi country from Koup6la and Tenkodogo) began ln 1939. The total number of detected cases of trypanosomiasis for the Tenkodogo cercle was 783 la 1942,1307 in L947, and L426 Lt L949. Apart from the focl of the Dougoula Mondi and Garango, which have already been mentloned, the disease appears to have been dispersed as mlcrofoci throughout the country. The Chief Medlcal Officer of the Tenkodogo medlcal distrlct treated 108 out of a total of. 270 cases of trypanosomiasls in the Garango Canton (13 OOO inhabitants), and 95 in the Konto6ga Canton (6024 lnhabitants). The flgures for the other Bissa cantons ranged between 2L ar.d one sufferer froD trypanosomiasis. It can in fact be stated that the Blssa country has been little affected by comparison with the Lobi, Gourounsi and Mossl foci. On the other hand, except on the left bank of the Dougoula Mondi (Tabs6 reglon) and perhaps in the Mandi6-Bagr6 Canton (oral survey), trypanosomiasls has not especially affected the people living along the rivers where onchocerclasls ls highly endemic. At the present time, there is no trypanosomiasls in the Bissa country (only one case lf,as detected in 1966 for the three cercles of Tenkodogo, Zabr€ and Koup6la). ocP/8s. s page 43 5.2 Other endemic diseases (1) Leprosy in the Bissa country: according to the 1966 annual report of the Bissa Rural Health Department, the average prevalence of the Bissa (60.9/1000) is one of the highest among the peoples of the Upper Volta; it is exceeded only by the Lobi (74.5/1000). For purposes of comparison, the l{ossi have an index of 35.4/LOOO and the Fulbe an index of 10.6/1000. In the above report, Sansarri.cq notes that the leprosy map in Upper Volta is, broadly speaking, superposable on the isohyets, and therefore correlates with rainfall. (This also applies, to some extent, to the onchocerciasis map.) In the Bissa cantons we have tried to establlsh whether the first-line vi11ag es i.n which 0. volvulus infecEion is hyperendenic exhibited higher average indices for the prevalence of leprosy t han villages away froo the first 1ine. We did not note any significant differences between these two population groups. (2) Intestinal parasitoses. Association of ankylostomiasis with onchocerclasis was reported by Richet (1938) and found again by Chastang (1951), but unfortunately preclse figures on this subject are lacking. (3) Schistosomiasis and malaria. The only survey available to us ln this area was carried out in 1951 by Chastang, who had been instructed to enqui,re into the disappearance around 1947 of sma1l villages on the left bank of the Dougoula Mondi. Chastang studied three population groups: (1) the inhabitants of four villages wlthin the cultlvated area (Garango, Pagou, Boura, Tangar€, 3637 persons exanined); (2) two villages (Lourgogo and Bargasgo - 907 examined) located nearer the rlver, whose inhabitants were continuing to work land on the very edge of the zone; (3) the refugee population from the abandoned zone. The examlnatlon was aimed at discovering: - indlviduals wlth onchocerciasis nodules, whose eye disorders were noted; - sufferers from trypanosomiasis; - cases of schistosomiasis detected by examinlng the sediment fron -centrifugation of the urine of 50 chlldren in each vtllage; - cases of malaria detected by investigation of the spleen rate and the parasite rate ln 50 chlldren from each vllIage. The results are presenEed in Table 20, from which 1t can be seen that there were many sufferers fron trypanosomiasis in the abandoned village of Tabs6 (we have already mentioned the part played by trypanosomiasis in this area). On the other hand, no significant increase ln cases of nalaria and schistosomlasis is to be noted on passlng from the third-llne vllIage to the first-line vi11ages, in contrast to the increase in cases of onchocerciasis and ln eye dlsorders. 5.3 Nutritional deflciencies ln 7962 a nutritional survey (Raoult, document WHO/0NCHO B 465) was coupled with the ophthalnological survey of Monjusiau in savanna and forest terrain to examine possible relatlonships between nutritional deficiencies and the ocular complications of onchocerciasis. This survey, which covered seven savanna vi11ages, including Niaogho in the Bissa counEry, 1ed to the followi.ng conclusions: (1) it cannot be proved that a specific nutritional disorder plays a major role 1n the appearance of the ocular lesions of onchocerciasi.s; (2) there is an association between vitamin B12 and niacin deficiencies and the ocular lesions of onchocerciasis; ocP/85. 5 page 44 (3) in the savanna zone hypovitaminoses of the type of pellagra and ariboflavinosis are more comnon in villages where onchocercosis is hyperendernic and in persons infested with Onchocerca than in other groups. Lastly, we should note that food shortages are sometimes mentioned in administrative reports, especially in 1936 in the Niaogho region, and in 1952, 1953 and 1955 in reports of the Zabr6 subdivision. 5.4 General disorders of onchocerciasis patients In 1939 Richet gave an excellent description of general disorders in sufferers from onchocerciasis in tl-re Garango cercle. Havlng referred to a previously published work (Ouzilleau), he writes: "For our part, we have noted the frequency of organic deficiency states, and even of cachexia in our patients infested with 0. volvulus"i Richet invokes the following factors: (1) the association with giant elephantiasis; (2) the intensity of parasitization and the accompanylng terrible itchlng, which causes insomnia; concomitant infections (dermatitis, lymphangitis, pyomyositis, which were known at the tine as Bissa disease); (3) pathological associ.ations, more esPecially ankylostomiasis. TABLE 20. RESTLTS OF CHASTANGTS MULTTPLE-PURPOSE SURVEY (1951) Trypano- Spleno- 0nchocerciasis somiasis Schisto- No. of megaly somiasis persons in Persons in examined children with Eye o1d New (malaria) children cysEs disorders cases cases (Puyuelo) Group I Within the cultivated area 3 637 LO7" 0 1.27" 0 62% 50"/" Ihird line Group II 907 l-57" 5% 2.57. 0 42"t 7 07" Second line Group III line First t2L 437^ LL% L7Z 0 7 67" 7 67" Refugee population froo Tabs6 village ocP/85. 5 page 45 Richet tel1s us that this set of pathological conditions lnvolves a reduction in working eapacity that leads to famine. Thus there is a vi.cious circle: volvulosis, ankylostomiasis, hypovitaminos i s . Survey on the general condition of persons infested with O. volvulus in the Bissa country (1) Working methods: ln the absence of long and costly multiple-purpose surveys, Ide considered it possible to determine differences in the general condition of populations infested to differing degrees by O. volvulus by the use of quite a slmple nethod: weighing. trfe weighed all adults, both men and wouen, In the villages in which we carri.ed out clinical and parasitological examinations. We distlnguished two SrouPs: a group of 114 men and 135 wonen from the hyperendemic villages of Niarba, Tigr6, Yakala, Foungou and Zarparia; a group of 86 men and 172 women from mesoendemic and hypoendenic villages (Nlaogho, Zar.gha, Beka Zourma). The observed weight of the men and women in Ehese groups was compared. The statlstical analysls was made by J. Coz, an ORSTOM nedical entonologist, who computed varlance and calculated the reduced variation. The following are the results: Men of mesoendemic and Men of hyperendenic vlllages hypoendemic villages flrst-line (second and third lines) Mean = 53.071 Mean = 57.058 Variance = 72.02 Variance = 63.38 t-coefficient=3.4 Women of mesoendemlc and Women of hyperendernlc hypoendenic vlllages flrst-line villages (second and thlrd llnes) Mean = 48.11 Mean = 5L.62 Variance = 66.75 Varlance = 48.06 t-coefflclent=3.99 The observed dlfference between the mean weights of the men and the women of the hyperendenic villages and of the men and the women of the mesoendemic and hypoenderoic villages is significant at a 5Z probability level. The poor general condition of the adult populatlon of hyperendemic villages ls evidence for any doctor with experience of savanna villages in which there are persons infested by Onchocerca. Thls impresslon is confirmed by numerical analysis of mean weights, which are basically the resultant of all the pathological factors in the whole of a given populatlon. This fact is of great significance to us. (2) Study of rnortality ln the first-line, second-line and third-line villages. We had access to the census returns of 196.5 and 1968 for the flrst-line vlllages of Sambar6gou, Zarparia, Yakala and the second-line village of Beka Zourma, also ln Zabr6. Canton, frou which we were able to extract deaths during these three years. The results are sumraarized ln the following table: ocP/ 85. s page 46 Inhabl tant s Blind persons Deaths 1965-1968 recorded recorded (excluding children) First-line village 229 27 16 ( Zarparia) First-line vll1age 193 10 t4 ( Sanbar69ou) Second-line v11lage 228 5 6 (Beka Zourna) Mortallty ls undoubt.edly greater in the first-line villages, in which onchocerciasis is hlghly endemlc with many cases of eye disorders, than ln the vlllages at some distance from the first llne. 6. Conclusions We can assert that mortality is higher and the general conditlon poorer in the flrst-llne vlllages where onchocerciasis is hyperendenlc than in the villages at sone dlstance frorn the first 1ine. On investigation of the present and past nedical picture of these two lines of villages we have not found signlficant differences regardlng endemo-epideroic conditions (with the exception of trypanosomiasis in one case some 20 years ago) capable of explalning these dlfferences In the sEate of health. Admittedly, the information at our disposal is partial aod it would therefore be extremely useful to supplenent these surveys by a study of arbovirus diseases and their vectors in flrst-line and third-line villages. In fact, as our knowledge stands at present, it seems to us that t,he level of O. volvulus infestation of the patlents is capable of explaining the general dlsorders of the inhabitants of vll1ages borderlng on the depopulated zone. Where onchocerciasi.s is a cause of blindness, i.e. in the first-line villages, it is also a conEributory factor ln increasing the [[ortality of adults and in gravely affecting general conditlon (in this connection sre rDay recall the dwarf, wizened adolescents and young adults encountered almost exclusively in first-llne villages, who are invariably highly infested by O. volvulus). How does onchocerciasls lead to these general disorders? In our opinlon it does so both directly and indirectlY: 1) Dlrect eflee!: through the following physical disorders: - the leveL of cutaneous parasitism wlth its corollaries of prurltis, insomnia and concomitant lnfection; - premature aglng; (2) Indlrect effecE t hrough: - pathological assocationsl elephantiasis, lntestinal parasitoses, .leProsy, malaria I - reduced working capacity arising fron poor nutrition; - premature aging of the whole population tl'rrough Ehe departure of young men and young women for healthier regions. ocP/85. 5 page 47 CHAPTER IV - THE ABA]JDOM"IENT OF THE VALLEYS Study based on adninistrative records An attempt was made first of all to estj.mate the general movements of population in the Bissa country on the basis of the existing administrative records. The sources available for consultatlon vrere the annual reports of the administrators of the Tenkodogo Cercle from 1921 (the date it was established) until 1968. The dennographic data in these reports are based on administrative censuses, whose inperfections are common knowledge. Since the censuses were used to determine the head tax, inaccuracies due to fraud may be frequent. However, for all their faults, these reports represent a valuable source of information. 1.1 Census of the total Bissa population Ihe figures given by the censuses are as follows: L92Lz about 110 000 L932: 93 000 7945: 90 732 1949: 109 000 1965: 177 000 A denographic sauple survey carried out in 1960-1961 by the National Institute of Statistics and Econoroic Studies (INSEE) throughout Upper Volta estimated the Bissa population at that time at 205 000. L.2 General evolution of the Bissa population Two periods can be dlstinguished: Between 1921 and 1946 one fact is certain: the total population diminished considerably and certain cantons (Tangar6, Niarba, Bangoula, ZLgla, Torla) became administratively non-existent; this fall in population was a source of great concern to the adEinistrators, who ascribed it to the following causes: (1) the compulsory recruitment of labour for the plantations in the Ivory Coast and major works on the rallways; (2) the high rate of taxati.on; (3) the excesses commi.tted by certain customary chiefs; (4) at certain times, and to a lesser degree, famine and epidemics (sraallpox, cerebrospinal neningitis ) . The three first causes nentioned 1ed to a spontaneous exodus of the population towards the Gold Coast (now Ghana). 1946, the year in which coropulsory recruitment of labour was abolished, represents a turni,ng point in the general evolutj-on of the population. Emigratlon, which had been particularly high in 1945 (7796 ithabitants left Tenkodogo Cercle) came to an end. The eroigrants returned to their vi11ages. During the subsequent years, the population considerably increased. The denographic survey of 1960 already mentioned indicated that the Bissa ethnic group had an annual growth rate of 22 per 1000 (in order of importance the second highest rate among the various ethnic groups in Upper Volta). The birth rate was estimated at 50.8/1000 and the death rate at 28.8/1000. 1.3 Evolution of the population in the individual cantons The authors studied the evolution of the population in the various cantons from 1935 till the present day with the help of the adminisErative reporEs. Their findings are summed ocP/8s.5 Page 48 up ln Table 21. Ihe population changes in the individual cantons followed the general pattern. Thus, an increase in population was observed in all the cantons after 1946, except in Lenga Canton, which as a result of a change in administrative boundaries lost a certain number of villages populated by enigrant.s (Y6ribas) between 1954 and 1963. L.4 Evolution of the population in the villages nithin the individual canEons We had available population figures fron adminisErative censuses for Zourma Canton (Zabr'e Cercle) fron 1934 to 1964. During that period in thaE canton: two villages disappeared; the population of two villages diminished, fron roughly 350 inhabitants in 1934 to fewer than 100 inhabltants ln 1964; in three villages, the population narkedly increased. It was also possible to study the way in which the villages of Namenda and Bangoula in Tenkodogo and Garango Cercles disappeared.(cf. Table 22). Although the population is increasing in these cantons, in fact it is only the villages 1n the interlor that are prospering. In contrast, the villages on the edge of the inhabited zone, on the banks of the watercourses are losing populatlon and even in certain cases becoming depopulated altogether. The authors will explain in subsequent chapters the significance to be attached to these facts. The role played by onchocerciasis in this loss of population was not mentioned in the adpinistrative reports until 1957 and onwards after the series of medical surveys conducted in Upper Volta after 1948. 2 Survey arnong the populations In the second stage, the authors attempted to suppleroent thelr original data by Eeans of a field survey anong the populations directly concerned by the abandonment of the valleys. 2.L Method of work In the first few investigations the following standard questionnalre was developed for submission to the persons covered. 2.1.2 Standard uestionnaLre I. Search f or abandoned villages Do you know i.n this region villages or quarters that have now been abandoned by their inhabitants? What were their names and where were they situated? Were they old villages or recently established (atteropts at settlement)? In this latEer case, at what date was the village est.abllshed? I,rlhere did the settlers come from? What was the slze of the vlllage ln its heyday? At what date did the last fanilles leave the village? I{here did they go to? Was the vlllage abandoned suddenly or gradually? 0cP/85.5 Page 49 TABLE 21 - EVOLUTION OF THE POPULATION IN THE BISSA CANTONS FROM 1936 tO 7967 Census populations CANTONS Tenkodogo Cercle Ban6 Population increasing Loanga Yargatenga Garango Cercle Garango Population increasing Sanogho Niaogho Lenga Loss of the Y6ribas in 1957 (mlnus 1666 inhabltants) Komtoega Population unchanged Boussouma Populatlon increaslng Zabr6. Cercle Yakala 3 Y6riba vlIlages attached in 1957 Gonboussougou Population lncreasing Zourma Zabr6. The Y6ribas are groups of Bissa who caoe to settle north of Zabr€ between the two Voltas. At different periods, they were counted in different cantons. It is therefore difficult to interpret variations in population for the Lenga, Yakala ar.d, Zabr€ cantons. ocP/ 85 . 5 Page 50 TABLE 22 - EVOLUTION OF THE POPULATION IN CERTAIN VILLAGES Census population Cercle Canton Vtllage Tenkodogo Tenkodogo Namenda Disappeared owing to admlnistrative changes Garango Niaogho Bangoula Dlsappeared Zabr6. Zourma Zourma Increasing Mouibango Yarsipiga Yalaga Decreasing Douuagou MoI Ma Disappeared Kouniani II. Determlnation of the reasons for the village belng abandoned (in each of the I{hy dld the inhabltants abandon the vl1lage? If the people giving the informatlon had not Eentioned them, the Person conducting the survey enquired about Ehe following factors which night have had sonething to do with the abandonment of the village: - depredations by wlld animals (lions, elephants, nonkeys); - compulsory recruitnent of labour; - ende6o-epidenic diseases: trypanosomlasis, stral1pox, meningitis, onchocerciasls; - rrere the inhabitants in good health? - rrere there an abnormal number of blind persons? - what was the relative importance of each of these factors ln the abandonment of the vllIage? - rras the soll good? - why dld the fanllies walt for ao many years (20 or 30 years) before abandoning the vlllage? III. MoveEents of the crop-qrowing "frontler" In the region, |s fhe crop-growing "frontier" recedlng or novlng forward lnto the bush? ocP/85.5 PaSe 51 IV. Resettlement of the abandoned areas Does the population of the region wish to resettle the abandoned land? If so, aEong all the unfavourable factors mentioned, which must be eliminated first (make sure that the persons giving the information realize the inportance of thelr replles and leave them enough time to discuss it among thenselves). V. Knowledge of onchocerciasis (the "disease of the trees") Llhat is the local name of oachocerciasis? Vlhat are lts synptoms and how does it evolve? I{hat causes it? Are the blackfly and other bitlng insects known? What are they called locallY? 2.L.3 Persons questioneq (I) The survlvors of the vlllages and quarters that have been abandoned. (2) The inhabtrants of the villages on the edges of the depopulated zone (notables, heads of fanilies, old people). (3) The customary authorities responsible for maintalnLng the historlcal records in their areas. Thus t6 canton chiefs, 1.e. all the Bissa canton chiefs and the Mossi canton chiefs in neighbouring cantons (Bind6, Mandi6-Bagr6, Gaongo II, Zounweogor Manga) together wlth the inhibitants of 20 villages on the edge of the depopulated zone were questioned. The number of points at whlch the questionnaire was used was thus 36. 2.L.4 Recording the results The names of the vlllages and quarters that have been abandoned have been brought together ln a table (the nunber attributed corresponds to that on the map). The ethnic grouP to which the villagers belonged and the years in which the village was founded and dlsappeared (Table 23) have been recorded. A few comments are needed on the value of the tnformatlon gathered. The authors went separately at different tines to the same survey poLnts to try to corroborate the Lnfornation recelved by the previous enquirer. They are, iror.r"r, of certain gaps: the site of the abaridoned villages, thei.r size and the dates of their foundatlon"r"i" and diiappearance are only approxlmate. Sone villages were classlfled as abandoned by their inhabitants, when in some cases one or two families are stil1 living Ehere, as was found by enquiries on the spot. 2.2 Results of the survey 2.2.1 Name and situation of the abandoned village s and quarters The narnes of L24 vi-ll.ages and quarters that have disappeared were gathered in the survey area: 87 had been populated by Bissa people alone 3" by Bissa and Gourounsi 2* bY Bissa and Mossi 2" by Bissa, Mossl and Gourounsi 38 by Mossi The Mossi villages in question bordered ironediately on the Blssa area that was studied. ocP/8s. s page 52 2.2.2 Origtn of the abandoned villages Out of 58 villages whose origin could be ascertained, 34 had been recently established. There seems to have been a considerable movement to settle on the banks of the river valleys betvreen 1913 and 1938, with a peak between 1920 and 1930. Out of the 23 villages whose date of foundation is known, 19 were established between 1918 and 1938. 0n1y one attempt at settlement was recorded after 1938 and that was at Nonoaghin (in the Bitou region between t.he Noahou and the White Volta). This movement for settling new lands was much less considerable among the }Iossi but did affect the populations i.n contact with the Blssa between Manga and Gomboussougou. The movernent tordards the valley lands fron the large villages seems, in rrany cases, to have been a means of escaping compulsory recruitment of labour and the exactions of the chiefs. Sone fanilies Ident abroad, whi.1e others formed independent villages in uninhabiEed areas. A few villages on the other hand (24 out of the 58) had been o1d-established. 2.2. 3 Size of the abandoned villages It is very difficult to obtain precise information on this point. Most seem to have been smal1 villages (between 10 and 60 fanilies), some were bigger (between 60 and 100 families). Two villages in the Bltou region, between the Noahou and the Whlte Volta (Porgare ar.d Zinzane), seem to have had oore than 100 families llving 1n then. 2.2.4 Date when the villages were abandoned 3 dlsappeared before 1917 60 disappeared between 1917 ar.d 1947 36 disappeared betweeo 1947 atd L957 25 have disappeared since 1957 Other vlllages sinply noved further away from the rivers, the village population renaining the same. Ihis applies to Tlgr6 and Korkaga near the White Volta. 0n the other hand, mention should be made of the special case of little groups of Hausa fishermen, who according to the 1oca1 people do not stay long on the banks of the watercourses. A departure of such fishermen after five yearst stay on the Red Volta and another after nine yearsr stay at Tigr6 on the Wtrite Volta have been noted. 2.2.5 Survival span of the 18 recently established villages or settlements Thls varied considerably: less than 10 years in the case of two villages; between 10 and 20 years in the case of six vlllages; between 20 and 30 years in the case of six villages; between 10 and 40 years in the case of four villages. 2.2.6 tr{ay in which the villages disappeared Wirh one exception (Zanbo), the disappearance of the villages was gradual rather than sudden. Families departed one by one. A few tried to remain, generally around the vll1age chlef, but ln the end went away in his company. 2.2.7 Places to which the lnhabltants of the abandoned villages moved Ihe surviving inhabitants of the abandoned vLllages retreated either to the nearest large village or to their village of origln (Garango, ZIgLa Po1ac6, etc., in the case of the Bissa). The Mossi, following the advice of the administratLon, sometimes went off to dlstant vlltages (Koubri, for example) situated some tens of kilometres fron the village they abandoned. ocP/ 85 . 5 Page 53 2.2.8 Changes in the frontier of the cultivated area The frontier of the cultivated area, in general, retreated at the same time as the frontier of habitation. However, i.n a few regions the frontier of the cultivated area is tending at the momenE to move forward towards the watercourses (towards the Dougoula Mondi to the north of Garango and towards the Tcherbo in the Sanogho, Boussouma and Lenga reglons). 2.3 Reasons for t.he abandonment of the villages according to their populations These reasons differed in different vi11ages. However, certain essentlal causes ernerged. 2.3.L Damage caused by wild animals was the reason most often clted: - ltons at BiEou, Lenga and Sanogho used to attack people and livestock; - rnonkeys (at Tanema in partlcular) were accused of plundering the fields; - antelopes ln Tlgr€ used to eat the growing crops; - elephants, which spare the Whlte Volta, seem very xouch feared by the populatlon along the Red Volta at Zabr€ and Zourma; - hyenas (Tanema) were blarned for thelr attacks on domestic animals. However, in other regions (Yakala) lt was said that wlld anluals played no part in the abandonment of the vllIages. 2.3.2 Conpulsory recrultment of labour for the Ivory Coast or the bulldlng of the railways (Dakar-Nlger, Abidjan-Niger) was almost everywhere consldered to be an essential cause of the depopulation of the villages before 1946. Other constralnts were also often mentioned: local denand for coropulsory labour, the compulsory cultivaEion and sale of certain crops such as cotton, and worklng as porters for the adnlnistratlon. According to the o1d people in the vllIages, many vlllagers came back as soon as compulsory recruitment of labour lras abolished in 1946. 2.3.3 Diseases Accordlng to most of the survivors of the abandoned vi11ages, the country they Ilved in "was not good". People were "killed by the bush". DeaEhs were very numerous. People died one by one before reachlng o1d age. Children, on the other hand, kept well untll they were seven or elght years of age. After that age they became weak and fe11 i11. An attenpt was made to determine the disease or diseases which those questioned believed to be the cause of these deaths. Ihe "disease of the trees" ("gono" in Blssa and "tiss6" ln Mossl) was always mentioned, followed, less commonly, by sleeplng sickness (at Bitou, at Tabs6 north of Garango and at Zambo east of Manga). In reply to our questions, all the inhabitants emphasized the large number of cases of bllndness in the abandoned villages. *If you go over there, you lose your eyes" (Zourna). Other diseases were associated with onchocerciasls: epilepsy almost everywhere, leprosy often, suallpox (Niarba), measles rarely (Kounlani). The inhabltants had no memory of major deadly epidenics of sudden onset except for sleeping sickness in Tabs6. Popular opinions concerning the "disease of the trees" (The disease whose ravages rrere so often described by the survivors froo the abandoned vil1ages. ) Local naroe: "gono" anong the Bissa "tiss6" among the Mossi and the Bissa living in contact wlth then. 0cP/85.5 page 54 Causal agent of the dlsease: "The dlsease ls caught by drinking lrater into which leaves fall fron the trees; if you wash with this water, you have to scratch a 1ot afterwards." Description of the disease the children remain well up to seven to eight years of age; a6 you grow old, your skin becoroes hard and rough like the skln of crocodlles (arrows cannot pierce iL); nodules appear ( "pauh" in Bissa); you have to scratch a lot; your chest grolrs smaller and your body shrinks; 1n the village, you see llttle old nen. These are young and snall people whose skin is like that of old peoPle; then you lose your eyes. To begin with, you see worse at dusk; the disease reaches the stomach and you dle. And yet the people were rich and ate well ("the land was good"); before, the disease was less serious; only the old people became blind; now even the young people go bIlnd. Eow better could onchocerciasis, with its cutaneous, ocular and general syndrome, be described? Popular oplnions regarding lnsects along the rlvers The loca1 people easlly dlstlnguish blackfly (they are called "gozir6" ln Bissa and "karfisse" by the Mosst) from other biting lnsects (tsetse flles, mosqultos, etc.). They know that blackfly blte ln the legs and that, afterwards, drops of blood ooze down the legs whlch become smeared wlth blood. To farm in the bush, the people have to put on trousers. They are bltten during the day and cannot sleep at night afterwards beeause of itching. Howlver, the farners do not establlsh any link between the blackfly and the "disease of the trees", which seerDs to them to be a disease of standlng water and of the leaves of trees in the bush. 2.3.4 Varlous causes Disagreements with chiefs were blamed in Ban6, Niarba, Kaibo and Yakala (the Mossi chief of Sanogo, Mustapha, regularly indulged ln extortLon round the year 1930. He was finally replaced by the adminlstration). A lack of women was blamed, particularly in Tigr6. "Women will not come to our village to get married because we have no money and no clothes, and the men are not stron8." Lack of food was rarely blamed, except in Tigr6 and Niarboa. On the contrary' people cl-ained thar "{n the o1d villages, there was plenty of millet and plenty to eat". Also blaned were difficulties of water supply in the dry season (Niarba and Zakour6). The spirlts of the rivers and the bush were rarely mentioned but do Perhaps have a certain importance in the psychology of the population. 2.4 Posslbillties of the popul ation returning to the abandoned areas Anong the inhabitants, a keen desire was noted to return to these areas where Ehey know that the land is good for crops, but they pose as a rnajor condition for such a return the disappearance of iirur blindness. Their only other problem is that of monkeys and elephants in certaln areas, a problem which, however, they consider to be secondary: "If there are a lot of us 1n gooa tteitth and if we have guns, we sha11 be able to drive then off". ocP/85.5 page 55 3. Critical study of the causes of the abandonment of the valleys 3.1 Summary of the characterlstics of the movement array fron the valleys This rnovement dates back a long tiroe. It is known that some villages disappeared over 50 years ago. Other villages, whose traces were found in some regionsr Eust have disappeared even earlier than that, since the loca1 people could supply no detailed infornatlon concerning them. The novement was couurron to all the big river valleys on which there are lines of S. damnosum breeding places (the White and Red Voltas, the Noahou, the Dougoula Mondi, the Tcherbo and the Kou1ip616 ). It affects only vlllages in the valleys situated on the edge of the uninhabited areas (Waddy rnade the same comment for the north of Ghana in 1949). The frontier of the inhabited area is still moving back. It has been doing so contLnuously despite attempts at resettlement between 1910 and 1940. During the last 10 years, an additional 25 viIlages, sooe of them very o1d, have been abandoned. At the moment the frontier of the inhabited area in any one region always seems to be narkedly further away from the watercourses among the Mossi than among the Bissa, who seem to have fewer places they can retreat to. Today, the Bissa population has stopped Erying to resettle ln the uninhabited areas (the last attempt for 20 years took place at Nonoaghen near Bttou). These resettlement vlllages dlsappear in almost every case less than 30 years after they have been established. The falllng back of the fronti.er of the lnhablted area i.s not always accomPanied by a simllar falling back in the frontler of the crop area, which reoains unchanged or is even being pushed forward lnto the bush ln certaln reglons (north of Garango towards the Dougoula Mondi and south of Sanogho tohTards the Tcherbo). 3.2 Factors leadl to the abandonment of the The rnain factors oentioned by the popuLations and also found in the administratlve and nedlcal surveys have been summarlzed in Table 24. 3.2.L Factors that have disappeared or whlch no longer play a parE (1) Coropulsory recruitment of labour had its usual adverse effects on all the villages ln the Blssa country but where it could have played a declsive role was i.n hastenlng the disappearance of small villages in the va11ey zone whlch had already become demographically unbalanced. This factor was important untll the abolltlon of compulsory recruitment ln 1946. (2) Disagreernents with the customary authorlttes (whose political power t.oday is very slight) inpelled certaln lndividuals or isol-ated groups to flee fron their villages. This factor was in polnt of fact operative throughout the country, and not specially so in the val1eys. On the contrary, lt seems even to have been a factor ln the scattered settlement of srna1l communities in the valleys between 1910 and 1940 (Hunter, 1966, in Ghana, made the same comment ) . (3) Lions and hyenas at one time caused very considerable damage. Today they are disappearing (as a result of the greater number of efficlent firearms Ln circulation, trapping and polsoning caropaigns carried out by the veterinary services). Although very nunerous ln the past, but they have practlcally dlsappeared from the Volta valleys for some years past, except here and there. If unprovoked, they no longer attack man. Their ravages among domestic anlmals are lnsignificant conpared with those caused by eplzootics and snakes. The often spectacular nature of thelr attacks and the fear that they inspire are the reasons why they were quLte often accused of being responslble for the disappearance of some villages. ocP/85. 5 page 56 TABLE 23 - VILLAGES INDICATED ON THE MAP IN FIG. 7 Year Year Name of No Ethnic Name of No Ethnic the vl1lage grouP the village grouP of of disap- of of disap- estab. Pearance estab. Pearance KarE 1 M 01d L957 0utare 42 B 1951 Zennetenga 2 M 1947 Linfou 43 B L952 Dawonogomde 3 M L937 Ztgla 44 B Zoungui 4 M L962 Berregou 45 B 1940 Koupelem 5 M L937 L947 Daya 46 B 1930 Nakiternga 6 M Soukonga 47 B Kankalaguea 7 M L922 L937 Limba 48 B Dakilissoumtenga B M o*d L957 Kisside 49 B L927 Dakoatenga 9 M L964 Wenegande 50 B 01d t927 Dondourl 10 M L927 L952 Porgare 51 B L927 Kossoumtenga 11 M t9L7 L947 Zegore 52 B 1940 Linoghln 12 M old L957 Koungou 53 B 1957 Zoungou 13 B ? ? Zoungou 54 B 7964 Boussltenga L4 M L937 L952 Sao 55 B 01d 19 60 Guirkt 15 1,1-B L922 L957 Zouni 56 B L922 1936 Gon 16 B 01d L967 Biouma 57 B Recent 7964 Kazanga 77 M 1930 Gargou 58 B L952 Tambaogofenga 18 M t937 1958 Dirlako 59 B 1963 Goumissi L9 M Sarobo 60 B 1953 Garian 20 M Koudougouno 61 B Niongore 2L M 1918 1948 Niantakoumeni 62 B Sarla 22 M 1925 1950 Boud6re 63 B L952 Ganbili 23 M 01d L966 Tissinpare 64 B 1950 Kabontenga 24 G L923 L948 Dounka 65 B MaIma 25 Gl,IB 01d L946 Tangare 66 B 1935 Koya 26 GMB t9L7 794s Ouanre 67 B Wennata 27 B L940 Loaba 68 B o1d L929 Teogotenga 28 M Soumpa 69 B Zanhire 29 G-B L9L7 Sonka 70 B L927 Kouniani 30 G-B 1913 1938 Kouki 7L B L922 Gargara 31 G-B 01d L942 ZLtzane 72 B 7932 Yambasse 32 B Badema 73 B old l-947 Tanga 33 B Belarnierla 74 B 1950 Saregou 34 B Tale 75 B Dangou 35 B Zambalga 76 B 1918 1950 Poussita 36 B 01d 1952 Nonoaghen 77 B 1956 L964 Sarla 37 B 1909 1940 Kakamogre 78 B 1918 L956 Bire 38 B 1955 Soadin 79 B 01d L943 Sunga 39 B Sougoudl 80 B 1938 1943 Dabri 40 B 1930 Patin 81 B 01d 19s8 Plfou 4L B 1935 Douraki 82 B ocP/85.5 Page 57 TABLE 23 - VILLAGES INDICATED ON THE MAP IN FIG. 7 (continued) Year Year Nane of No Ethnic Name of No Ethnlc grouP the village SrouP the village of of disap- of of disap- estab. pearance estab. Pearance l,l 1900 L927 Noignedegogo 1 M L937 Moetenga 22 L927 1950 2 M 7937 Gombo 23 B Karkuiyaguen L948 Tanema 3 M old t947 Kalhindi 24 B 1950 4 M L927 Tabse 25 B L924 Bekouma L948 Sera 5 M-B 1960 Galgani 26 B 1948 Ibogo 6 B L964 Sorogare 27 B 1948 Nontenga 7 B L942 Niaye 28 B 194S Zlmpata 8 B New 1950 Santaria 29 B New 1950 Kourgo 9 B L947 Bassouwego 30 B B 01d L952 Yeletenga 10 B L937 L947 Gourba 31 L957 Nonka 11 B L897 L927 Zamsse 32 B Tigre L2 B 01d Bougli 33 B L96s Goutinga 34 B L9L7 Bangoula 13 B (very Nabitenga L4 M New L922 Kayan 36 B 37 B long Zakour6 15 14 L957 Bourma Nonka 16 B Feleta 38 B tine) 1950 Gul1a L7 B New L932 Saropali 39 B 1950 l4ozi 18 B L922 Zepa 40 B L952 Zambo L9 B L9L7 Nonda 4t B Klra 20 M Norghin 2l }T old L964 Villages indlcated on the nap in Fig. 5. Sao18L9231933 Nonoaghen 2 B 1950 Abbrevlatlons: B = Blssa M = Mossl G = Gourounsi The nuobers of the abandoned villages have been plotted on Figs 5, 6 aod 7' ocP/85. 5 page 58 Antelopes are also disappearing very rapidly for the sane reason as the predators, but also as a result of poaching (hunting at night in particular) which is intensively practised ln some regions. Some speci.es which, as litt1e as 10 years ago were very nunerous, have today aloost conpletely disappeared from certain uninhabited areas. (4) Trypanosomlasis, which in former times depopulated a few scattered villages ln the Bissa country, has practically disappeared today. 3.2.2 Factors sti1l present Some of Ehese operate both in the valIey villages and in the villages in the interior r*rere the populatlon is constantly increasing. They could not therefore be cited as uajor factors ln the abandonment of vlllages; they include voluntary emigratlon to neighbouring States, a wldespread phenomenon throughout Upper Volta, adverse economic factors which are unfortunately also very widespread (shortage of food, lack of wat.er) and the different endemic diseases (rnalaria and varlous parasitlc diseases) together with eptdemlcs (smalIpox, cerebrosplnal menlngitls, treasles), which do not particularly single out the valley regions. Next to be consldered are the factors at present leading to abandonment of the valleys and the way in which they should be classifled. (1) Depredatlons are stll1 belng caused by wl1d aniuals: Elephants still damage crops in a very restricted area on the banks of the Red Volta, but only occaslonally and during short periods. Monkeys are certalnly a nuisance to farmers. Their numbers have possibly increased over the last few years as a result of the disappearance of the predators. Troops of several dozen monkeys, particularly dog-faced baboons, a very self-confident assured and sometimes aggressive specles, are dlfflcult to chase away from the flelds in the case of small village communities with the bush presslng close in around them and at great physieal disadvantage (bllndness, etc.). Thls is why in the opinlon of some of the inhabitants monkeys have been a factor in the dlsappearance of a village. The lnhabitants of solidly established villages, on the other hand, are perfectly well able to get rid of these undesirable guests. (2) However, an essentlal role today is played by unhealthiness of the abandoned areas. Ihls unhealthiness ls shown essentially by excess Dortality, a high incldence of blindness and a poor general state of health among the adult population, which is found only ln front-llne vlllages. Thls ls the essential fact. Excess mortality is blaned by all the former inhabitants of the villages now abandoned. IE was found ln our survey ln the front-line villages. Bllndness is the scourge of these front-line vlllages. It suffices to recall the figures: LOZ of blind persons ln a vlllage as a whole, l5Z of the population over 15 years of age and 302 of certain fanilies, but this i.s when only total blindess is taken lnto account. If persons with severe eye disorders are included the flgures are even more alarming: over 40% of the population above 15 years of age. The siek persons Ln a single village could, by thenselves and for several nonths, take up all the beds in a university eye clinlc I Even to the casual observer the poor general sEate of health of the populatlon (dwarfism, cachexia anong o1d people and some young adults) leaps to the eye and it was confirmed by a calculation of the mean weight of adults. This phenonenon too occurs only ln the first-Iine vlllages. In the chapter on clinical conditions (Chapter III) it has been shown Ehat onchocerciasls, lndisputably the cause of the cases of blindness, is also the major factor in these general disorders, probably because of supervening infections, a combination of several pdthological conditions and a decrease Ln working capacity which leads to the Lmpoverishment of the fantly concerned. Likewise, anong the biting insects, it is blackfly that are the major nuisance, since they develop and bite rnainly during the croP season. In some places people may be exposed to so nany blackfly bites that they are forced to move away (Waddy, 1950; Philippon, Congo Kinshasa, personal comnunication). The fact that in sone areas ocP/8s.5 Page 59 (d(0 UrJ Floo Fl Hz €€ frl &&oo, o o q, oJ = rJ ts t UtJ z o E] oo a a ]J }J rIl o & () Eid Ar oo .-lta .Fl rI1 r+{|+{ H oodG H ()(J za r, o(, u) tr rr>r ld o q, o O-{ H 0, t{ r-{ = r+{ (0 H t{o .H> ++ + + ++ & o fs] U oo (! a,c e (,)+J o o fr{ r-t o z t{ H (, (r-) I @ o frl d u F1 FI >r oo (d .Hx r+i o -ta .r{ F{ IrI OF{ o o(0 ++ + + H ! o> o (D h rJ o o (,) PE (0 o+J zH r t frl o Fl zA tr}) ca +JO rr(! t0 h-{ tro .c-r o O 'r{ El uOlr oq{ a OF{ H oo6 }{tr + + !Fl o@ + o o .F.l H IJoro>r uo Otrh cdtr o 64(u .Fi 2 h F.l o H a Fll-too e & EI Ff @0ro a .Ho & TJ TJ o ..t (! H lrU o () oa o E , ...,1 t\ U bI) € o )v ! r (0rl o a o li l; o lrh) IJ u z 5HO o d o o(u.0 c, l+{ o o H o .oE-d (,) o TJ tr H t{ (!0@ o c rx o F{ rJ .F.l lr .{ .Fi lr (J rJ oo o(0 d o t H o +,E o bol o ${ o f& (! 'c{atOU t0 'r{ dc o r+{ rJ H (! o !tr tr '-l o (U u a u (.) aJ (d O.){J o F{ 6 a FI ld X 'r{ (0 aq tl (! orJd CE, .cD o) lr o. o) @ .r +{ EO 6F{ o o o@ r{ (J o U .C .r{ .Fl -x .H U o.(d d +{LtU €! o! '\, 1rO O FI E o 4.4(0(,J o tr tro >t (6 O r-{ r.{ lrBlili o>! OE o (a do rJ t+{ .dil € (,)@o fr3 .F{ o'} .rl .F{ U, (! .Fl ri> x \f 0, U, .Fl lJ Fl U) E o 'Fl O CJ F{ F.l tr 6l (! lr+JEO fx6 a o tU r,) 'Flo tU t0 r+{ @ (t trl (! .Fl c! E..{ rJ O tro(B r+{ o € otr.Ft E] F{ >\ o o ..o '.{ E .'i 0, t tr .r{ l+{ (! r.E>r ^ ..{l o@ o oo€o@ orr o FC'J o OOIiO OU !uo, o O H trO E O ,a urO6.rl @(d otroo I o 0., o ..{ ri ,o o H lr F{lrrrA (6'd u(6xc o troEoo rJp o o Jdoco u0) (!.do(! E dOlrottr-c l{E d u a.(!5d t.tr !a)a.o o cl E oE o o (d 6I) o o Eulr-iO oo. ootr...{ € >r O .Cr{ O > O. +{ o o..too .co h.-{o5 6 litr{JAXo oo p u) al AE]EZ o Fr O OO 14 Ar atr ocP/85.5 page 60 such as Niarba, the population manages to stand firro despite the hlgh nunber of bites to whlch they are exposed every day nay be due to the facE that the period of mass blackfly bites is very short (1-2 nonths per year). Tsetse flies are also a very greaE nuisance in certain areas but much less for the farmer clearlng the bush than for the hunter or flsherman. The entomological and clinical sections of this report have shown the close relationships between the distribution of the exposed populatlons and the severe ocular and general conplicatlons of onchocerciasLs on the one hand and the situation of the depopulated area on the other. At the Doment, therefore, onchocerclasis is the major factor ln the unhealthiness of the villages on the borders of the depopulated zone. Thls unhealthlness causes fear or distrust of the bush, a powerful psychologlcal factor which causes the population to flee fron the front-Iine vllIages to villages nearest the centre of the area and llkewlse dlscourages the other lnhabitants in the interior fron making any attenpt at resettlement, however eager they may be to find cultivable land. A study of the recent evolution of the village of Yakala serves to denonstrate the role of onchocerciasls in the slow disappearance of a village. 4. Denographic study of a vlllag e where onchocerciasis ls hyperendenic Yakala vil e Yakala canton Zabr6. cercle A conplete medical census had been carried out in Yakala in 1963. t{hen the vlllage was surveyed tn 1968 the authors thought that it would be valuable to carry out a new census in order to see how the village had evolved over a sufficiently long perlod of time (five years). fhey noted deaths, departures (enlgration to nelghbouring States or villages' departure of women to other vlllages to get narried), births and incoroers. 4.L S ituatlon of Yakala village 1he village of Yakala is 2 kn north of the Whlte Volta, on the left bank, at. 24O m above sea leve1 and 26 m above the bed of the river. S. damnosum breeding places exlst in this area (Flg. 6). These breeding sites are of llttle importance except when the Voltars flood lraters finlsh receding, as is shown by the results of catches of fenale blackfltes (Table 4). Hlstory of Yakala village A customary vlllage (formerly cantonal capl.tal - the capital has now been noved to Foungou - and the place where the chiefs are buried), Yakala, according to the lndlgenous 1ocal population, wa6 much bigger in former times. The village was also surrounded by vast cultivated areas, as is shown by aerlal photographs of the region. Between Lenga and Yakala there are nunerous sltes of villages that have disappeared (Sao, Zougou and Kourgou towards the north-west, Zoumi, Bourma and Feleta towards the north-east and Pousslta to the east). The population of Yakala village has gone down. Accordlng to the latest censuses the population was 309 ln 1953 ar.d L27 in 1963. 4.2 The demographic evolution of Yakala village fron 1963 to 1968 ls surnmarized ln Tables 25 ar^d, 26 ocP/85.5 Page 6l o It @ (!0, E .Ft o a t) '}{(uOF{ .cu o, r-{ (d F{ o F{ ud u h'.1 .r{t0 O 4^ o F{ > t+{ .d Bt r{ @ z .r{ o tro.r .N E o '-'l .,r=ootr Eo\ (! !.c Fl F{ .r{ tU F{ tqrJo F4-{ O oIE F{v U' +J F (! 6t -$ fr) !J@ + I I +{ \O Efq EE 14 E{ fr{ !o\ EErq td-l F{ r'.1 d) 6l (Y) o Fl .+ ln o 6l \ON o F{ ,{ F{ d H th tr o a o x o FI H H = h o FA @ !J Erq 14 14 \o tr () o\ FIN (vl F{ F.l la FI I FI c") t^ 'r, t{ \o o, o oo^ o\ o d^ hrr ^^(0r.lE .r{ o r-{ o tr6t ! o tr l'tr.l !"{ tr rd.s o(0c,l{o tt ttt J a 5or >O.Cdu (UrJ u ()-{ t-{()() E, aa v L v vO vo rd o Err fa o (f) F.l F{ fqo a F{ -t N-l z !O o o H @ N H t, N ct'nN d) D o Eo\ EO\= O\ o\ FI o F{ F.l Fl F.l o a r-{ v F{ v6t (r) fr] @ U rrr (!t 6l u (f) .r{ \O tqE h IE t&=h 14k El po\ =E Fl (U F{ c\l NF{ 6t @ F{ .if .if (7) (\l .+ F{ .f I\ -{ (n 4 '-{ F.{ F{ 4 a Fi H h >\ h Fl -.1 .r.{ r{ -td E a E 6 (0 (d l+{ t+i |+{ a c t+{ o t+{ o l+{ o oo t oo lr oo tl {J ! F{ rJ Fl rJ t FI t (0 d-{ F{ (0 €-l F{ 6 .O _t F.l 6, +J (05 ,Ft TJ 65 i{ u or o ot o ot o !c< (J H :tr< (J H (J H (n zo Fl N ocP/8s.5 Page 62 o.l i I 4F @O AO\ OrrO@>i rn sl @ .f o0 (a rr. l. r+{ F.{ tr (0 NO\ c.tE c!tr o € OFr, B o\ F{ oo O\ s{ >t p (nF{F{+l O (t Ft t{ Fl! o o r{ >fa .o v.o rovr+{-l v(u o z -.c (l,) e tr6 trH l+{ET. o > o, t{J -lEFl ..{ E c! E+{ o A = r0.d o F{ Fl F.t 3 5r.o -t NJ-uq{N €Np EQ r-l E Fl OHFI uo d 6 cl rj@ + +{ \O o EE fq E frr EE fq Por F{ 6-l I r-{ tn f\ \O F\ \o r-{ c) (f) o o o (\l a t H o o a fl u o tr lr o o o a o o I tr FI H H Efr x€ srh @ rJ EI \o l{ fq Err (J o\ +{ F{ ta FI FI (Y) 6l rn FI I F1 (n 'o^ H \o oo I I o\ o r{E F{ o !rl o\ FI k lrO .$ { a (!U o\ ort o 4 ! F.l ot k voE) v(0 -t * (, d LU} F A H E(0 fq !r, o ,d, fq F{ F{ n() o a -lEo z q !A o o € r{ .c o^ o\ o o O^ H r, FtO\ -{O \O .$ \o NO\ p q, EO\-lfrO\rn E(no\ Eo\ EO\N Ff o F{ O\ F.{ O\ o\ F{ _t Ft o\ o a N vF{ C..l vFl .+ 6l F{ Flv (7) N vF.l trr o U tr t\ (0 N rJd) Fl \O E E fr tr EE f:{Eh EE t\ frl .oc (f) .f .f .if F{ (7') Fl t0-l -.1 N o F{ \o r\ \o -t la F.l (\l tr H li x >r h F{ F{ Fl r.{ 6 E 6 (U (d (! l+.l t+{ t.|{ F l+{ c) r+{ o l+r o ta tr oo lr Oo p € Fl +J \, F.{ +J ! r-{ F.t d d-{ r+ d €Fl 6 a r{ rJ d3 '.{ u d, o t o ot E o ot () H o H =E< rd< .f zo rn \o ocP/85.5 Page 63 oot (0f. €-f, o -c(d tro\ o o 'Fl Fi l.J >r o. FI o Fro. p z .r{ d rnO Eo Eo-, t! '.1 O\ O\ fr€ (f) F{ F{ o r, (6 N .+ N U@ I I I po\Fl \O h 6-l (v) o o tn .i o\ Ft t H o J tr Fl ! a o o t{ o o o rr5 (u E ouoo o ..{ (u o lr OF{ -l lr r)F{ H H .(0 tri e -r E.H > F.l E{ F o ta .c @ tl rlt \o l{ E fr () o\ F{ tEt st \o F{ F{ Fl I Fr (Y) @ H \o qa I Ot o | '.{ F{ o F{ O\ tl \o t (n.fa .f g a o\o\loo or1J o 4, }J Fl^Fl .o 60 F{ ot !l tr v (! v^Jd d (u tr O@-r ! (r, o. E (lE!.lrlF{ ktrrJ o ,f 6 O-{ (t, fr o C' tr > (n o -tc)N-{ -tEo "..t z o o H E \' oo o F U .f ON o p (d EC'r EO\EO\ ft{ O\ .1 o r-i Fi FI F{ o a F.{ Flv F{ F.l vF{ v F{v (Y) Ir1 (rt rJ 6 N r, cf) r{ \o Era fr tt h trl FO\ EE t!F{ (\t (\l .+ (f) Fl 6t F{N -{o F{ \O F{ co E Fl F.{-t H H >\ x F{ r-{ ri E d (0 (0 (}{ U{ tr a tr q,) t+{ o t+4 o lr oo Ir Oo l{ ! F{ }J 'o U o F.{ F{ (0 -{(d €-l Fl 1, F{ F.{ (! .r.,1 U (05 rl U (!, .Fl rJ o O'c, o ot o () H !E< () t-r o H zo T\ @ ocP/85.5 page 64 r+lr+{ ?E| ^ r\ ooo trol{o o 6l t{ >\O (d td o o OFI o.C O IJ FI >ilt{ O. o v'o .u FI E OE O. z a d > (U AC' q' E '.1 d tr tH .'.{ O _{ F{ , .f, E'r'l F.{ p € (/) 6F.'r B€ uo (! \o 6l F.l rr@ I + I E{ \O E l\ fq Po1 EEr.{ Efr t0F{ c7) Fl 6l t\ F.{ \O \O tn F{ o\ o o a -t ! H o a F IJ tr o o tr o o oE o FI H H t\ o 14 .c @ ! H \o l{ (9 o\ r{ E FA (r) (r'' F] -tI FI (") fr@ H \o otr rJ o\ o i+{ r{ lo Ft o fr. l{ or(u tr !, .SO .1 a (f)ooo o\ q) u T' .o OI) F{ ,l ! ra !.c (U vh (, t! @-{ t{ F A E O. +.1 r-l f+O o (?t€O Or{ ok a tr > \o FtH ,-{ z o o l-{ .s ts u o i] 6 Eol FI o FI o o F.{ H ah rJ d r\ (d N r,(f) +{ \O EE fqEfq EEh E r:{ E rd FO\ Ff (!ri F.l 6l .C 6l .if (n Fl 6(n d) r/) N F{ EA E F{ -t tr -t ts H h h >r r-{ FI Fl +{ .Fl E a E 6 (0 (! t+4 l+{ q c l+{ o r+{ o l+{ Oo tr oo ,r o ri ! r..{ }J € Fl FI tFl r{ (d 'O Fl (! u (! (U5 .r{ u (d,-l t, (0 u ot o OE o o o ;E< () H !E< () H H o o\ o F{ z Fi F{ ocP/ 8s. 5 Page 65 Er{o)I t+i(,,!Ooor@ o otrr+{.o_{ .c-r ho@@'F{ ! d+{ > '-.,1+{ O.F{ O AE AO !00dE tr h.C O td"{ o U tr (d rJ@ po\.rl \O tfqEfq d-{ F{ F{ F.l .if E -.1 a € H o a tr .'.{ a U o d .'i o +J o (! }J oo I r{ FI E ErqErq H d H Fl Fl F-{ F{ .if = E{ x ttl lq co rJ frl \o }{ (J o\ .il F{ FA FI I Fl (n H \o o\ o F{ o lr FI a U lr v (! x o. o) ofr. a z Ho CD H U (U oFl ao fr1 o rJ d ln (0 (\l !(n .'.{ \O rI] po\ o oooo o Fl tllF{ cat ,ct H H x Fl E 6 t+{ G |+{ o o o! +J€ F{ t F.l F{ r! G J 'r'{ rJ @ €E o ts o 6t z Fi 0cP/85.5 Page 66 o r, t t o o € t{ t{ o (0 (! o {J o) o rJ (, o. A d ! o o o @ 6 (0 E r{ o o E a r{ o otr t t C' >,o h h ,-{ @ ,{ FI +{tr .'.{ .r{ F] EA 6 E (!0 6 (0 v hh r Fq F k uo o tr r\ o\ o F: rd o o o \o o o o\ F.l (, cO +) o F{ FI N FI orF\O r{ F{ FI Ft(0 Fl E l-{ a r{ td H Hz o tr co o F{ u, E ()o\r'l\O o ZF{ to o2rdo l-.1 () (Y) Hdt (r) iE \o @ FI ul 6l F{ ai or rJ ()zd ! O trl EE rdBE rrr F{ OH at) EI o rd ca t{ FI (f) F.l ri 6l (r) F{ \o FI H .J fr l. o Ar0 o & A 4 E D o U' TJ F{ (f! .s (Yl N F{ (') F.l (! oo d N o ET p Ff co d (t') (r)rJ co .+ (7) o .+ 6l i$ FI r\ F{ H \oil FI F.l (\ F{ F{ F{ F{ orP -t (, -{ E tr .r{ (D o -{ F.l FI N cr) -+ tn \o F\ @ o\ o -{ E FI F{ r(0 ocP/85.5 Page 67 o pF{ d E +J o o +J tl o c t,ll .r{ o E TJ E F{ o ..{ t FI o (d(da r!p E Br..H uo) oo d 'J a z> o I o Fl \? o F\ (n U h IJ o o \' rr tr d o Erq E fr{ r4 @rJ F{ o (9 \O F{ l{ orp \o rn F\ T\ $ (?) (t) FI F{(0 F{ F{ FI E H t o +{ li t{ o ida a F<€ t o o (Y) o a Htrza u 6 (! .t rn F{N F{ 6l o tt) t) lr Htr @ F{ o ()0 .r{ E rr. Z<) a rJ dv E fa o@ H o0 \o \o r{ (.)or ,{ ti HFi o \o F{ O\N t piA !J 42 lr € d< .H E r o C) F4 -l O fr) Fl t E\O I frl Or (7') o\ o AFI o Fl o o B taz F{ lr ! !E ET o\ o o\ d @ H IrI U Fl o \o B tr -t x o\ frH d FI OH A Erq .if co o OF{ t I a (!otl & ou o >\ (t) E th o \o c) N tal o\ =(n u co Fi FiE F-{ (7) (0 F{ o o tl{ a a E O r+4 o = o d h Oo B e\,1 t ! IA oo o ld +J N rn lo 4 Fl d co .f Olr lq q, oo tr (?) !J r\ trQ ! Ei \O .r{ (\ rn r/) 6r\ o o c.o FI .f (t) F{ cl oI € F.{ r! E [tr tr c o o +{ Efr Ere (,)}f t +J ro 'o Fl Fl F{ o ,-r 'r{ t' dE E o tr(0 <() () o oo r{ o t{ >r F{ F{ u E (0 r-{ -{ .+ q, E rJ J ''.{ Fl rJ (d o ! .ct o fr E< C)o z ocP/85.5 Page 68 Ihe onchocerciasis file for the village was reproduced in the clinical survey of the Bissa focus. It can be surnmarized in the following tab1e. No. I.Iirh Slight eye Severe eye Bllnd from Suffering Age-group examined onchocerciasis disorders disorders oncho- fron (positive biopsy) (r & rr) ( rrr) cerciasis leprosy 0-14 36 11 9 1 2 15 years and over 64 60 29 L6 10 13 Total 100 7L 38 L7 10 15 4.3 Concluslons (1) The decrease in population recorded over the past five years is due to the following causes: (a) excess nortality among the adults: 16 deaths aroong 82 adults; (b) departures of adults or faroilles who have emigrated outside the area: 12 men, 11 women and two chlldren; (c) rnany young men leave for good to go to Ghana or the Ivory Coast; (d) the women fo11ow their husbands or still more often marry in the neighbourlng large villages (Foungou, Gomboussougou, Y6riba villages). The loss of 43 inhabitants was not matched by increases (17 live blrths between 1963 and 1968, the return to the village of a Y6rlba famlly whose forebears had come fron Yakala, one marrlage with a woman from outslde the vlllage). The overall result was abandonment of the village by two whole familes (rillth 10 and four members ln 1963) and the disappearance of an o1d faruily whlch by 1963 had been reduced to a single individual. (2) The factors responsible for this loss of populatlon work gradually: deaths and departures follow one another, then suddenly the family reaches breaklng point and leaves the vlllage. A good example of Ehls process is provlded by fanily No. 4, which in 1963 comprised one head of fanily, two male adults, three fenale adults and three chlldren: Two nen, born in 1910 and 1919 respectively, died in 1963 and 1965. Two women, born in 1919 and 1950 respect.ively, dled in L964 and L967. One 20-year-old woman married in Gomboussougou. At that stage, therefore, only one head of famtly (blind), three women and two glrls were left. The famlly left Yakala and settled at Foungou, a much bigger vlIlage. Fanily No. 7 disappeared as follows: out of four counted ln the 1963 census one died and three adults departed for Ghana and Ivory Coast. (3) The present situation in most of the fanilies is a matter of grave concern: Two families are sti1l prosperous (Families Nos 1 and 10), including the chiefrs family, which is always richer than the others. One fanily is ln normal balance (Family No. 11). ocP/85.5 Page 69 On the other hand five families, totalling 63 persons, are out of balance. Famlly No. 5, although increasing in size, includes three b1lnd heads of famillesl two young men (32 and 36 years of age) died; three ldomen are widows. However, there are numerous children. Thus, the working capacity of the famtly is already reduced. If the adolescent boys and girls leave the vitlage to work outside or to get marrled this family will soon be bound to dlsappear. Fanily No. 8 comprises three bltnd persons, out of nine in all, and three bachelors. There are no children. As women from outside do not come to Yakala to get married, what will become of this fanily in a few years? Family No. 6, consistlng of seven persons, includes one blind head of fanily, one twenty-year-old adult suffering from dwarfism, severe onchocerciasis and leprosy and one wonan suffering from leprosy wlth deforroities, as well as three children. Fanily No. 9 is disappearing: of its 13 nembers five settled at Gonyanga and one girl married outside the vlllage. There remaln one blind head of family, hls wlfe, one bachelor and four chlldren. One fanily, probably after a disagreenent vrith a chief, has settled ln the village but it comprlses trrro adults, who already have severe eye leslons caused by onchocerciasis, and two young children. The only posltlve element cones from outslde: a non-commlssioned offlcer, llving in Ouagadougou, does a lot for the vlllage (he pays the taxes for a large part of the village and distributes money and clothes). It nay be inagined that wlthout this elernent the village would have suffered stil1 nore. Ilowever, if Yakala is left to tts fate it is very likely to disapPear in the falrly near future. In brief, the essential reason for the gradual disappearance of YakaLa is the state of health in the vlllage (numerous deaths, numerous dlsabillties: bllndness, elephantlasls and deformlties due to leprosy). Whlle certain fanilles are succeedlng in keeplng themselves together, others are ln a very precarlous state. Working capacity is dlnlnlshing and departures are belng organized. The young men go abroad, the young women marry ln other villages. These departures are not, wlth very rare exceptions, oatched by lmnigratlon fron outside (the women fron neighbouring vlllages do not wish to come and get married ln Yakala and some famllies end up by leaving the village en bl*). The main factor ln the physical deterloration of the vlllagers ls onchocerciasis, whlch causes bllndness ln this vlllage to a frlghtening extent. Ot 74 adults over 15 years of age, 10 are bIlnd, slx others are suffering from very severe eye leslons and almost all of theo are sufferlng from a severe degree of onchocerciasis whlch inplies lnfectlous leslons ln addition, elephantiasis (assoclated with Bancroft fllariasls), prenature aglng and dwarflsn Ln some lndivlduals. Furthermore, 18 adults are suffering fron leprosy, often with assoclated def orrolty. It is therefore easy to understand the young people leaving the village whlle they are still healthy, young people who do not Eanage to flnd someone to marry and cannot bear the heavy burden of their families (widows, chlldren, old people, the blind and the cachectic). If an external facEor (cornpulsory recrultnent, exactlons by the chlefs, food shortages, etc.) cones lnto play the process speeds up. Thus the death of the vlllage is consummated. In brief, this five-year survey of a vlllage with hyperendenlc onchocerciasls provlded a better understandlng of the process of abandonment of the v11lages and the way it ls regarded by the inhabitants. The factors leading to the vlllages being abandoned are so lnterwoven and act so slowly and gradually that those concerned only remember the more spectacular aspects (wild anlmals, food shortages, high nortality). 5. Study of a particular case: the Niaogho region It has been seen (Figs. 6 and 7) that settlements by the Bissa people on the very banks of the llhite Volta were relatlvely dense Ln the past. Of those settlements only a few lsolated vl11ages that are now disappearlng still remaln (Yakala and Foungou), together lrlth a considerable nunber of people concentrated in the Nlaogho region. Slnce the major role played by onchocerciasis ln the movenent away from the banks of the Volta rivers has been well docunented, questlons obvLously arlse as to the reasons which enable this populatlon in the Nlaogho region to stand put in an area where there are whole series of blackfly breeding places. In the authorrs oplnlon the reasons are as follows: ocP/85. 5 Page 70 (1) The breeding sites of S. damnosum on the White Volta in this reglon are lsolated and snall; some of thern dlsappear during the flood season. Moreover, no blg tributary passes through this group of vlllages, except for the Dougoula Mondl in the north. Even that, however, does not have any breeding places for 5 or 6 km upstream fron its junction wlth the Volta. The Nlaogho region therefore occupies a relatively favourable posltion in regard to large breedlng sltes of S. damnosum. (2) fhe population thus settled astride the Volta totals almost 15 000 persons (the cantons of Niaogho and B6gu6do and part of the canton of Ouar6gou) il an area of about 50 kD2, giving a population denslty of almost 300 inhabltants per knz. It will readily be understood that the relatlvely snall blackfly populations from the breedlng sites in this populated area are considerably diluted in such a large group of people. The result is that the lnhabitants in the centre of the populated area (in the vlllages of Niaogho and B6gu6do, for exanple) probably only receive on the average a small number of lnfective bites. On the other hand, infectlon seems to be on a masslve scale in the llttle villages on the edge of the populated area, towards the large breeding sltes on the Koulip6l6 to the south-Irest, the Whlte Volta to the north-west and the Dougoula-Mondl to the north-east. There a1so, the frontler of habltatlon ls stlll retreating, as ls shown by the recent (1965) disappearance of the vtllage of Bangou16, which is somewhat isolated to the north-Irest of the densely populated area. The vlllage of Niaogho itself ls therefore protected by this line of outer vlllages or quarters and lt is easy to see why, although it is slt.uated on the bank of the Volta, an ophthalnologlcal survey led to its classlflcatlon as a second-line village (Table 18). Moreover, this masslve settlement inplles intense bush clearance, which probably tends to keep a more or less conslderable fraction of the fenale vector populatlons outslde the cleared area. (3) The growlng of foodstuffs and market-garden crops whlch is carried on in the reglon earns lts lnhabitants lncomes that are hlgher on the whole than those of nelghbouring reglons. Food shortages are much less to be feared and the general state of health ls narkedly better than in the other viLlages sltuated near the Volta, such as Yakala. In addltlon, thls relative prosperlty leads to exchanges of population (marriages, etc.) whlch are to the advantage of Niaogho vlllage. Several posltlve factors emerge fron this survey and they nlght help human populatlons to Eaintain thelr settlements ln the i nedlate nelghbourhood of certaln serLes of breedlng sitesi they lnclude: - very dense settlement; - sources of lncome hlgher than the average. This, moreover, brings us back to the factor that maintalns the prosperlty of a few fanilles ln vllIages ravaged by onchocerclasls (famllies financially supported by soldiers, for example, at Nlarba and Yakala). ocPi 85 .5 ?age 7 1 CHAPTER V - THE CONDITIONS UNDER WHICH CULTIVABLE LAND CAN BE RECOVERED 1. Stud j-es of various possibili ti-es of controlling S. damnosum A campaign to control S. damnosum must nearly always be spread over a long period of time and is often di.fficutt to bringre a successful conclusion. lts imPact en the evolution of rhe endemic disease is generally not perceptible until several years have elapsed. It is for rhat reason that the authors consj.der it essential before entering upon a djscussion of the various methods of control to define the general characteristics that a control campaign would have to have in the reglon under study (Le Berre, L967). 1.1 General characteristic s of a control campaign 1.1.1 Framework The uninhabited areas along the major watercourses in the Bissa country constitute only a small proportion of a vast area of land to be recovered for crops (nearly 9000 kmz) on the part of the White and Red Volta basjns that lies in Upper Volta (between 11-N and 12'30N). Consequently, any project for controlling the vector in the Bissa country should be so planned as to fit in with a larger-scale project designed to recover, over a Eore or less long period, the whole of the land in these va1leys. 1.L.2 Definition of the ob'iect-i-ves Since up ti11 now it has always proved J,mpossible to eradicate S. damnosum a vector control campaign must aim at reducing the female populations in order, i not to interrupt, at least to restrict considerably the transmission of onchocerciasis. In view of this, the anbjtiousness of the objectives will depend on whether it is thought enough to reduce transmission sufficiently to prevent the occurrence of severe disorders (damage to the eyes and impairment of general healttr) or whether the more or less long-tern aim is to eliminate the endemic disease altogether. In any case, and unless the establishment of breeding sites can be prevented once and for all (by the creation of artificial lakes), there can be no question of stopping vector control operations until the reservoir of human infectjon has been eIi.mj.nated, since otherwjse the protected zone would be more or less rapidly reinfested. The duration of control operations must be at least 15 years (the life span of the adult worm of 0. volvulus) unless a para11el treatment canrpaign makes it possible to eliminate the reservoir of human infection l{rithin a shorter period. 1.1.3 The control methods at present used Since attempts at direct control of S. damnosum females have never succeeded, the basis of any effort to control the species is stil1 the elimination of the pre-imaginal instars. Thjs can be done in two ways (Le Berre, L967): Destructjon of the larvae in their breeding sjtes. This is achieved by releasing insecticide into watercourses upstream fron the breeding places, at intervals o f time less than the duration of larval life (in the reglons concerned weekly spraying is generally practlsed). This procedure almost always requires the establishment of a considerable network of access tracks to the points where the insectj.cide is applied. Aerial spraying can also be envisaged, subject to previous triaLs. A campaign of thj.s kind should be carrjed out methodically, strictly and precjsely. Any relaxatjon of supervision or error in the amounts of insecticide appl-ied may have very serious consequences (massive reinfestation of the protected area by the vector, ravages among the aquat-ic fauna). Prevention of the establishment of breeding sites This consists in eliminating an ecological factor essential for the 1arval develo pment of S. damnosum viz, a sufficiently rapid current (between 0.70 m and 2.00 m/second). Apart from localized activitj-es such as the destruction of rocky obstacles or breeding places on artificial substrates, this can be done by building dams that will create reservoirs big enough to submerge vast areas where breeding places exist. However, the dams nust be designed in a way that will preclude or considerably reduce the possibill'-ty of breeding sites beconing established in the spi.llways. Visits to over 30 dams in the east of Upper Volta (Balay, unpublished report) showed that evacuation of flood water through ocP/85. 5 Page 72 spillways at one or both ends of the structure always created very large S. damnosum breeding p1"""" on medium-sized dams. Furthermore, it is very difficult to use inEEEIiciaE-to eliminate breeding places on these lateral spillways because some of them are very wide (600 n in the case of the l"Ioktedo dam, for example). A central spillway (along the axis of the former river bed) seeras to be the only satisfactory solution. It should take the forro of eitl-rer an inclined vertical veir, or a standard-crested weir; both shapes of weir, at times of flood, confine S. damnosum breedi ng places strictly to the corners of the spillway. These breedlng sites generally occupy a limited area and can be easily elininated through the use of insecticides or by simply brushing the place concerned. The only period during which they may spread on the weir is at the end of the flood period when the sheet of water crossing the spillway becomes very shallow. Thls threaE can be removed if the dam has a system of gates with sufficient throughflow capacity to absorb these residual flood waters and thus permit periodic drying-out of the spillway with consequent destruction of the pre-imaginal instars by desiccation. However, it would seem possible to preven t the establishment of S. damnosum breedlng places on a dam altogether by evacuating flood waEer not through open channels but through the body of the daru (a procedure similar to that used in hydroelectric dams). Exanples are the Akosonbo dam in Ghana and the Bia dan in Ivory Coast (Marr, personal communication; Le Berre, personal comrnunication). t.2 s electlon of a control proiect Control operations, whatever the method enployed, will only be a success if human populations can not only settle but also remain settled in the areas at Present uninhabitable. They should therefore offer the best possible safeguards agalnst any subsequent masslve reinfestatlon of the settled areas. There are tl^ro ways of avolding this threat: - eliminatlng the main breeding areas once and for all by building large dams so as to prevenE excessive breeding of female blackfly; - in the case of control operations based soIely on applylng insecticides, making sure that they can be pursued over a long period and possibly on a permanent basis. While the financlng of Che first years of a control c,ampaign (particularly the attack phase) can be undertaken by external sources, provision should be nade for the Upper Volta budget itself to assume responsibility after a more or less brief period. ContinuaEion of conErol operations (maintenance phase) should not therefore exceed Upper Voltars budgetary capacity. In either case and to help remove the threat of reinfestarion, a parallel canpaign of treatment leading to a rapid reduction in the reservoir of human infection seems to the authors to be essential. 1.2.1 Insecticide barrier Implementation of a project of this nature, under the auspices of WHO (project AI'RO-131), entered on its first phase at the beginning of 1968. The region to be protected covers the whole area between the White and Red Volta in Upper Volta and Ghana. The project aims at establishing a wide insecticide barrier by treating permanent breeding places on watercourses in the White Volta basin i.n northern Ghana and Togo. Since this barrler is being established and maintained during the dry season, it is hoped to delay the appearance of breeding sites on temporary watercourses further north and t.hus reduce the development of female vector populations. Ihe first results obtained in 1968 have been quite disappointing. While efforts to control permanent breeding places in Ghana produced satisfactory results (902 effective according to Scheffel, personal communication), they seem to have no effect on the reinfestation of the Upper Volta breeding places (see Table 28). Hotrever, such a caropaign should not be condemned out of trand, particularly as from the hydrological point of view the 1967i,968 dry season proved parti.cularly unfavourable (flow in the White Volta stopped for less than one Eonth in the Bissa area). ocP/8s.5 page 73 TASLE 28. COMPARISON OF DAILY CATCHES OF FEMALES AT POINTS E AND F BEFORE 1968 AND IN 1968 Point E Point F Months Fortnight Average t966 1968 of foul 1968 years 20.70 (3 2 00 (8) January 1st ) 2nd 2.00 (1) 9.43 (7 ) 1 00 (16) 1.27 ( 11) 1.3s ( L4 2 00 (1s) February 1st ) 2nd 0. s (1) 2.25 (4) 0.57 ( 23 ) 0 22 (14) 1st 0 00 (15 0.00 (4) 0 18 ( 60) o.27 ( 1s) March ) 2r.d 0 12 (ls) 0. 06 (16) 0 19 (64) 0.12 ( 16) April 1 S t 0 13 ( 1 5 ) 0.73 (15) 0.55 ( 51 ) 4 07 (1s) 2nd 1 33 ( 1 5 ) 2.00 (1s) 3. 35 ( 45 ) 3 13 (ls) 1st 29.22 (e) 20.10 (13) 2r.20 47 42.80 (1.2) May 2nd 43.57 (7) 723.20 13 1 Ar"..g" of the years 1963, L964, 1966 and 1967. The figures given are the mean for several catching-days. The number of catching-days is given in brackets. This project, if it succeeds, will improve the state of health of the populatlons at present living in the area to be proteeted but does not seexo to provide sufflcient safeguards Eo a1low for settlenent in the valleys. It is based on insecticide treatment that is mostly, if not entirely, carried out i-n two foreLgn countries by 1ocal teans. An excepEional hydrological year or a failure by one of these teams or a group of thenr (relaxation of supervision, stoppage of spraying as a result of social or polltical disorders, etc.) would be enough to breach the insecticide barrier and thus lead to massive reinfestation of the breeding places in the region concerned, with the caLastrophic consequences that may be imagined for populations newly settled in the valleys. Upper Volta would be completely powerless ln the face of such reinfestati.on, since it would not have available the considerable resources needed to conbat 1t (spray teans, access tracks to the watercourses, etc.). The situation would be different, however, if the land was resettled only when protection was available fron big daros which submerged the areas where lmportant breeding places exist (a project whlch will be dealt with later in thls paper). L.2.2 Local larviciding campaign No part of the region belng surveyed can be isolated during the rainy season because of the multjp11cit.y of the breeding sltes and the wide distrlbution of S. damnosum females Thus, any atternpted insecticiding campaign [Bust necessarlly cover most of the perlod during which there is sti1l a flow of water in the streans. The blggest efforts would have to be deployed during the ralny season, that is to say, under the conditions that are most unfavourable to such work because of: - difficulties of gaining access to spraying pointsl - changes in the effectiveness of insecticide application (sudden vari.atlons ln the rates of flow, flooded areas); - extremely difficult working condltions. Consequently, there is a risk that vector control operations of this kind w111 have poor results that will probably vary greatly fron year to year and from zone to zone in the area to be protected. 0cP/85.5 Page 74 Furthermore, the extension of a project of thls kind to cover all the breeding places on the White and Red Voltas (development of all the valleys) would require considerable resources. At a first approximatlon 15 spray teams would be the mlnimum for ensuring control. It seens unlikely that the Upper Volta budget would be able to assume responsibllity for paying them on a rDore or less long-term basis, partlcularly as the onchocerciasls focus on the I'lhite and Red Voltas is far from being the only one in Upper Volta. Under these clrcunstances the authors advise strongly against a project of this kind. L.2.3 The building of large dams fhe bullding of dams, quite apart from any idea of onchocerciasis vector control, has been consi.dered by the authorities in Upper Volta (particularly by the Board for Water Resources and Rural Equipment), who are lnterested in developing the Volta va.lleys. In these regions of temporary watercourses it is a problem to find water not only for the needs of hunan populatlons and their livestock but also to water dry-season crops. It energed fron exchanges of views with those responsible for these servi.ces that iE rvas perf ectly possible to plan dan projects in such a way as to succeed in ellninating vast areas of S. damnosum breedlng. To give an ldea of what a vector control operation based on a set of dams could be like' our choice fell on the region in the north of the Blssa country (see Fig. 7) for which most lnfornatlon rras available, in regard both to the endemic disease and to lts vector and where, r1oreover, the shortage of cultlvable land ts particularly acuEe. The daros lndicated have been emplrlcally sited without taking lnto account the condltions needed for building such rrorks (the existence of favourable sites). The artlflcial lakes were drawn on the basis of cont.our llnes plotted on maps at Ll20O 000 (reservoir at contour line 240 m for dams Nos. 2 and 3, and about 230 m for dam No. 1). In drawing up this outline of a control scheme a certain number of essentlal measures whlch someElmes have conflictlng effects had to be taken into account: the creation of vast lakes of iupounded water stretching far up the secondary tributaries and thus able to submerge the greatest possible number of breeding sites, particularly in the areas where the biggest sltes are found (course of the lJhite Volta, middle and lower courses of the roain tributaries, lower courses of the secondary tributaries) ; - the bulldlng of as sma11 a number of dams as possible, in case it is known, that a breeding place may become establlshed on the spll1way; - the submerging of as sma1l an area as possible, particularly in regions at present inhabtted or cultivated and in the vast zones of rich soil (vertisols as they are called in the ORSTOM teaching report) whose recovery is one of the objectives of the control pIan. Such a set of hydraulic works should, by itself, make it possible to stop any conslderable development of female vector populations. It will have to be supplenented, at least for a few years, by loca1 insecticide applicatton or an insecticide barrier (as in the case of project AFRO-131) and by a campaign of treatment designed to reduce the Present reservoir of infecElon as rapidly as possible. Local insecticide spraying wilI be nerely a supplementary operation, since control w111 be assured for the Eost part once and for all by the dans. In the region under study, it would consist nainly in: - treating the reaches of the White Volta downstream fron dams 1 and 3 frorn June to December. If iE becomes necessary to elimj.nate breeding places after Decenber, it could be done by opening and shutting the dam gates to produce alternate sluicing and stoppage of the flowl - treatlng the headwat.ers of tributaries with breeding sites of this species fron July to SepteEber. ocP/85.5 Page 75 Another question that may arise is thaE of the impact such hydraulic works migttt have on certain other endemic diseases (ma1aria, schistosomiasis). Hor,rever, on the one hand, these are not dj.seases that would result in a new abandonment of the land and, on the ofher, it is not certain that the lakes formed above the dams would worsen the present situation. In the last analysis, the building of big dams seens to the authors to be a sine qua non for any attempt at resettling the valleys in the region under survey. However, drawing up a project of this nature will require very close cooperation betrseen the various departments concerned and, in particular, when it is a question of deternining the site and characteristics of the dams to be bui1t, betl^7een water exPerts and entomologists. 2 Role of treatment in onchocerciasis control 2.L The aims of an onchocerciasis treatment campaign (a) The prlme objective of any campaign Eo treat onchocerciasis Eust be interruption of t.ransmission. It must not be considered as a supplenentary means of controlling the blackfly vector. Eradication of that vector is impossible to achieve at the momenE in the large foci. However, as has been seen, a reduction in vector numbers is possible. It is reasonable to hope that by conbining it l,rith a reduction in human infectlon through treatment, interruption of disease transmission may be achieved more quickly. In the first stages, it will be possible to try to naintain the amount of infection below the threshold aE which severe eye and general disorders aPPear. Later' the amount of infectlon wi11, if possible, be reduced below the threshold where the transmisslble parasitlc dlsease appears. It will then be possible to consider that onchocerciasis has been stopped in a partlcular focus. (b) The second objective may be a reduction in morbidity, particularly through a decrease in the severe eye and general disorders that in the villages most affected by onchocerciasis have serious social and economic consequences (abandonnent of the 1and, abandonment of the vlllages). It should not be forgotten that even in the total absence of any reinfestatlon, the eye will continue to be damaged by the microfj-lariae from Ehe worms that had developed in the patient before the beginnlng of the control campaign. Thts danage will continue while the worms continue to be fertile, i.e., for a maxi.mum of 15 years, or rather, in our estimate, for seven to elght years because of the natural death or aging of the adult onchocercae. If, on the other hand, it is possible to destroy the adult \rorms in persons not subjected to reinfection, several years of nlcrofilarial production will be avoided. Aged patients, who have been lnfected for too long and in whom the process of degeneratlon of the chorion and retina has evolved independently, are beyond any therapeutlc help. In the younger age-groups (10-30 years), on the other hand, therapy will indisputably be able, to reduce the lncidence of severe ocular disorders. (c) Finally, it is essential to insist at the outset on the psychological aspect of treat.ment. The populations involved are being 1itera1ly decimated by onchoc.erclasis and know the evil reputation of the river banks. Hors can there be any hope of persuading them to settle on the new lands if they do not feel thenselves to be under nedical protectlon? The populations very seriously affected by it must be given the benefit of specific medlcal treatment against onchocerciasis, together with multipurpose treatment against associated disorders. 2.2 The means of treatment, their effectiveness and their dangers This section will not deal with purely ocular treatment, such as nydriatics, corticoids and the treatment of secondary ocular hypertonia, since it cannot be practised on a big scale. Insteadr lt is the etiological treatment of onchocerciasis that will be discussed. Such treatnent, if it is to have radical effects, must ki11 the adult worus and the ulcrofilariae. A table below summarizes the advantages and disadvantages of the classical, well-tried means of treatment already widely used in onchocerciasis foci in Africa and Ameri.ca. ocP/8s.s Pa8e 76 (1) Methods aEtacking the adult worms (macrof ilar lcides ) Drug Advantages Disadvantages Suramin or (1) Very strong effect on the (1) Need for doses repeated moranyl adult worms every week (minimum six lnjections) (2) Strong effect on the mi.crof ilarlae (2) Need for inEravenous injection and measurement of (3) Toxiclty can be reduced by urlnary albumin levels adapting the dosage (0.20 g followedbylgxsix (3) Need for follorv-up of the injec t ions ) patient after the injections (4) The possibility, though they rarely occur, serious or even fatal toxic reactions Nodulectony i1) Safe (1) Only attacks a percentage of the adult worms (2) Very much appreciated by the patients, who ask for it (2) Must be repeated (3) Requlres consi.derable numbers of staff and amounts of materlal and dressings (2) Methods attacklng the microfllarlae in the skin (microfilaricides) Drug Advantages Di,sadvantages Diethylcarbamaz ine (1) Kills all the rnicrofilari.ae (1) Very weak action against the ( Note z ine) adult worns (2) Does not cause serious and fatal complications (2) Needs long and repeated courses of treatment (3) Causes important allergic reac t ions The present therapeutic armamenlarium against onchocerciasis 1s not easy t.o manage. To use it to besE advantage, it is essential to adapt it to the epidemiological realities by treating in the nain the populations at the greatest risk of transmitting the dj.sease and the most seriously affected by it. In such patients the risks of the antiparasitic treatmenE. can legltimately be accepted. 0n the other hand, populations who tolerate their onchocerciasis well and are not a serious transmission risk may progress to clinical cure as a result of a reduction in vector numbers alone, without it being necessary for them to undergo sometimes dangerous forms of treaEment. ocP/85.5 Page 77 2.3 Patient.s to be treated 2.3.L The villages This point has been emphasized already on several occasions. In the Bissa focus severe eye disorders, damage to the general state of health and disastrous economic consequences caused by onchocerciasis are nainly found in the front-line villages bordering on the breeding sites or at the edge of the depopulated area. In the second-line and third-ltne villages ocular cornplicatlons are much less severe and less common, there are no general compllcations and the demographic and econooic situation is satisfactory. It is therefore the fronE-line villages that should be treated. In the protected area outlined on the map ln Flg. 8, it would be enough to treat about 70 villages out of the total of 170. The cantons of Niaogho, Lenga, Yakala, Boussougou, Zourma, Mandi6 and Bagr6 will have t.o be treated almost in their entirety. On the other hand, lt is only the front-line villages that will have to be treated in the canEons of Komto6ga, Ouar€gou, Sanogho, Loangha, Tenkodogo, Gaongho, Manga and Bind6. Very roughly speaking, the total number of patients would amount to 25 000. However, account will have to be taken of those families recorded by the census as living in the villages in the niddle of the area but who, in fact, farm in the bush and are therefore highly infected. 2.3.2 Age-groups Analysis of the onchocerciasis files in the villages shows the line to be fo11owed. In hyperendemic villages it w111 be necessary to treat almost from the age of 10, since fron Ehat age onrrards all the population is infected and serious ocular complications begin to appear. 2.4 Selection of type of treatment In the lTyperendemic vil1ages, if it is wished to make any considerable reduction in the reservolr of infectlon, it wtll be essential to administer mainly the macrofilaricides, which are the only drugs capable of destroying adult worms and the microfllariae they produce withln one or two years. Treatment with Notezine and nodulectomy on their owrt will only be possible in children under 10 years of age or as a supplenentary form of therapy in other patients. 2.5 Organization of the treatnent campa]'gn 2.5.1 Flxed treatment bases and staff The need for protracted repeated treattrent and follow-up of the reactlons of the patients oakes it necessary to establish nurnerous fixed treatment bases. From these bases varj.ous rounds can be organized in whlch treatment will be given periodically by well-trained nurses. It will be necessary to double the size and staff of the present di.spensaries. Temporary strengthened adobe buildings should be enough and a nurse and assistant nurse should be provlded 1n each centre. At the moment there are dispensaries at Garango, Niaogho, Kalbo, Boussouma, Lenga, Gogo and Gomboussougo. New treatment centres will have to be set up at Tan6ma, Komto6ga, Yakala, Foungou, Dassanga, Ounzeogo and Bagr6. Each treatment centre would be able to deal with 2000 patients. SEaff needs for treating the protected area would therefore be as follows: 1 supervisory physician 2 technicians, responsible for the treatment teams on the right bank and the left bank of the I,rlhlte Volta. They could be based at Gomboussougou and Garango 13 nurses ocP/85.5 Page 78 13 auxlllary nurses 13 labourers (one per centre) Every labourer should have a blcycle. Every nurse should have a power-assisted cycle. Every tean chlef should have a cross-country vehicle. 2.5.2 Materlals and medicament,s needed Apart froo specific drugs for Ereating onchocerciasis, provision will have to be made for surgical lnstrr:ments for excising nodules, and also for materlals and medicaments for all types of care. There can be no questlon of treatlng only onchocerciasls among populations sufferlng frou a very wide range of diseases. 2.5.3 Duration of treatnent The patients ln this area are often difflcult to reach because they are conEinually on the Dove. Thus, a canpaign spread over five years seerns to be the mi-niroum if tt is wished to reach the greatest possible number of patlents ln the vlIlages. The drug treatuent w111 have to be carried out only ln the dry season (October-June) for the tvo followlng reasons: (1) Ease of rlovemeot. In the rainy season the roads are impassable. (2) Ease of treatment - In the rainy season the paEients are in the fields. The disadvanEages and inability to work caused by the drugs would certainly not be appreciated by the population durlng that perlod. - It shouLd be noted in this respect thaE trlal treaErDent with Notezine in Sar6gou village, from a base in Lenga vlllage, during the 1963 rainy season, ended in compleEe failure because only a very small percentage of patients turned up for treatment (MonJusiau) . 2.5.4 Cost of the treatment campaign The difflculty of launching such a treatment campaign will be easily understood, not only In regard to the maEerlal needed (drugs, premises, vehlcles, dresslngs) but also in regard to staff. The authors are convioced, however, that, lf it is really wished to push onchocerciasis back and to launch the Bissa region on the road to economic recovery, the effort would certainly be worthwhlle. If for various reasons only a proportion of the means needed for such a campalgn were to be avallable, it would be possible, and very valuable, to restrict treatment to a sma1l focus (that at Niaogho, for example) and to compare the resulEs obtained ln the treaEed focus wlth an equivalent unt,reated focus that was nevertheless Protected agalnst the vector (Yakala). Ihe information that. could be obtained from an operaEion of thls kind would be extremely valuable for estl-mating the possibllities of an onchocerciasis control caupalgn in the Bissa region on the basis of t.he entomological and clinical survey work done in this area. 3. Conclusions In concluslon, effective vector control, together wLth a treatment campaign, should not only make lt possible to open up large areas of rlch soil for seEtleEent but should also Lncrease consLderably the economic potential of numerous villages at Present ravaged by onchocerciasis. ocP/ 85. s page 79 ACKNOWLEDGE[,IENTS We wish to express our deep gratitude to His Excellency Mr F. Levasseur, Ambassador of France in Upper Vo1ta, for kindly placing at our disposal the Embassyrs Broussard aeroplane an,l its crew. We wish also to thank the air crew, lvlr Bonnefond and }lr Marchand, for Ehe ski11 and kindness which they invariably showed during numerous flights we made together. In addition, r^re r.rish to thank all those persons who, by giving us information, contributed to our work and, in particular: - the comrnanders of the Cercles of Tenkodogo, Garango and Zabr€; - the chiefs of the various Bissa cantons; and - the priests 1n the Zabr€ and GaranSo Parishes. SUMMARY The authors studied the important onchocerciasis focus in the Bissa country in Upper Volta from the entornological and medical polnts of view. An analysis was nade of the various historical, social, economic and pathological factors which have contrlbuted to the abandonment of the valleys of the Whlte Volta and Red Volta by the population. It was concluded that onchocerciasis, in its various asPects, has been in the past and is sti1l the rnajor factor ln that abandonment. Solutions that would nake it possible to resettle the abandoned areas have been studied and proposed (vector control together with a treatment campaign). ocP/85.5 page 80 FIG. 1. SITUATION OF THE BISSA COUNTRY a (y \ iE z= tr, tr) o (9 () I ao o J o (, z l! - (5 a a :< \ u f co (rlrl J o a{ o= Lrl (fF o a a{ o ocP/85.5 page 81 FIG. 2. THE BISSA COUNTRY c, lo z ..I9 +oF o d .'+ .,{ lrJ tr o t u c,r 'o ,'. 0, , o t'O o ot CF , (ri l{A tr E '! .i: OJJ E " EO ee) o. c, utr d.' L 2 l. oo0 f' o li o '. ,11' t o' ---y* .'* :s r' , ,. ''r+ f, +.'.'. (!r! ')l / UU .'r , +.'<. t I s' .'Z (u(t,OA noq tr..' ..<' oo o , o tro (, l-..': .5 (! od + th !O x ?n .J trlr(!c, '9. ,l ()(J FA dt ----J___ t E)@ @,' I I a- - , ! ! ,l rl I {f.---., I l+.,'. \\ \ I I \ oI t 'i..'. E'I \ \ t- '* I \ I I o I (9 o o , z o G i c :'.(, I a-_s : rd, a- \ .--,{P--- -.'q I ;.t.a or I ali cl I 1 !r t t t:o .?; i o, o l: of ---! , ,l --*i --- -i r., 8! FIG. 3. SEASONAI, VARIATIONS IN TITE DAILY BITING PATTERN (POINT E) Nullipares Parous A11 females TemperaEure E % females a t, t ! :-o DRY SEASON, HOT I I 37.5 I s I I I o,2 a Lt i 30. I , I I : 0,t ic , I i 20. I I It. I I 0 DRY SEASON, COLD I T 35. 2i lt ta I \ 30. l0 200 I I '12. I 10. I I 0 t I I RAINY SEASON I I t tI I T I I 30. 0. i I I i I .( t0 I 22' t 20. i : ! i ?t 0 .i. 6 t r0 t? IE h 58 12 l( 16 iu ,} ocP/85.5 Page 83 FIG. 4. DAILY BITING PATTERN OF S. DAMNOSIJ}I FEMALES IN RELATION TO DISTANCE FROM BREEDING PLACES RAINY SEASON Females caught near the breeding places (Point E) Females caught 6 km from the breeding places .0 I 4 I A- A11 females I I I /\ ,l t I I ,\ I I /\ I I /1 , t I ! I I I I \ I I I I t I \- I n 30 / t I I I I B Nu1 1 ipares I I I 20 /\ I \ t \ I I I I t I \ t \ t 10. I I \ t I It I l0 Parous C- t.ur"f"t /--\ ro t,' \ - -4. \"----zJ --- ),' 0 557a9rort12ll la t5 l5 t1 lt trl ocP/ 85 . 5 Page 84 FIG. 5. TIIE BISSA COUNTRY SOUTII-EAST REGION (71 fr N o o qj (l, a ?r F{ 2 (d .o (u E E H (n a rg0) t rd & o o (.) o 0, E H J, z E EI th Ff if N] (! 6 o) or o .o 3I o po (, o ! rd F{ t t 0, EI 0) z r! l. v) dl t H u>. H (h (! 'dl o(,) (d o! a \o l+{ 0) 6o, rI1 a tro (,)'i t{ l-.1 o o .t o. td Fq (^l Eo5 A O '.'l & TA o +J F{ .o d >r, ca .J U} (d6 EI rd 0, q{ .,{30 o 6 o o BrC ..{ .c 0, A H b0 .r{ d o t ;f . r.l rrl{ U) u H al, E{d5 (,) (d'r{ z fq A t!A q) rJ (,at) (,l o H a q) ! -9 .co) z t{ o l{o0 o {JB E O t u.C a o rutr rJ d ..{ do!,."{ e H l+l (I, (0 B Ee r, t{ t, a H (\l (d !r U Otr l(, o 'dd o .c (/, l< oGl +J E.E N E Ei ''l t+a N u 'E,Olr an lH E uo .F{ lr oNl{ c t{ ,E o o ;{J (alo o rd rH oo f! & u !p .r{ oo o> frl (, tn (0 q, o q) o, E F{o o t{o} Ff -o(d -cd Fl 'o lr o> z o dB 'r{ d rd (! uH o .r.r o tr .J O r, (uJ H (J tr cd q, c, a 3cn H z H ifJ a o C)(, Fq + H OP d o(0 H o a trl tr oc@ H (, 1..{ il A + )+< J c)(/) J o..oo(d t ; F5 ce@ i"( +.H , , o I --e- -g + e , (, t (\. o + I 6l + 4 e e + + + + + 'g + I r9 + + (\. tr, \ t oo +t @ r, I + &>{ @- \i E I H \ + z + ozoo @ l-{ .rlr_r 'a ,-' c. (nrll At.l* a& a \-/--/ + raHl-{ l+ (n l+ + @ l+ HI H l+ .o l+ rn u) o e, + z o @ I + () o{D oh' 4'1' z'z' -' t- __+ H +-- I k I 19 ocP/8s.5 page 85 FIG. 6. THE BISSA COUNTRY SOUTHERN REGION 1l .-:@ ,t * .L61.' t+ 'ri + ," l + z @ /a + ,t s/ + , + :E u t @ o I (9 ,g . i--f&..': I .t '3 t o ..t , a @ I t I I I @ I s. '! :o + \-3 :@ ,@ /a M )v €,e o o 0 .ti CI @ @ oqroq, I Y4\9' al @e ? @ a I , @ , t J I t ?a' @ I E/' g.eo'l -@-j: o \ 0 e 9-- I @. .t I E o, F t $). e, o 6 a\ I FIG. 7. TIIE BISSA COUNTRY NORTHERN REGION O o e E U o , t , t o , t t t , o 69. O I e e e t e o e ry o @ "o - 'ril .re/ O -@ I @ 9:q@ %I , aI e @ \y ffi I @ \sl I o , I @j t (D '-"-t-.. 6 e @ e o EE<-( @ r .i:.. \ ri. '6) .x. o. .E/ aD St. t t. f I I ,:...... t6 "t? I s I ffi , O ocP/85.5 Page 87 FIG. 8 SUGGESTIONS FOR THE CONTROL OF S. DA}'INOSIJM IN THE NORTH OF THE BISSA COUNTRT- :i at .t Kcttr ng.1 2 oungou o a I I I .\.l I I I /- ...... '1. 't ...... 1 "l o .\ \ I .:' .l \ "a')-'- e , t , a-/ B 4? /- (s Cictgayc €m(l .. :'. t.\ I .to 9 O.U_ \ E I 't I 8.3 , t 8.2 I ,..... t I t. -.:.. ! 6GARANGO n1 i:., TE$ .? 0 :'. ll Ioogo o ':t 1., .! io'ibo L t' l: t. it€ t Xotl'lrP , ANGA \ \ I-t \ I i- .: I I 7 o \-I -r-1 '." t. .. :: N 'i:'. .t Yokola I o t Baqii I e \ \\\ \ ..\ t I -:-'- i-.'\ G SOUgoU a 0 t0 Km :l Boundaries of the boundarles ot the protected =-=s'--r croP-growing area area B .1 Virgin lands 1 Vertisols Dam (ORSTOM report) ( Other soils Larvicidal control operations (to be envisaged) --Gt+rrs.-!F- ocP/8s. 5 paSe 88 REFERENCES BALAY, G. (L964) Observations sur lrovipos Ltion de Simullun damnosuu Theobald et Sinuliun adersi Pomeroy (Diptera, Sirouliidae dans ltEst de la Haute-Volta. 8u11. Soc. Path. Exot-ZG-):s88-611 BAtrAY, c. (1964) Sinuliun damnosum Theobald inullidae) sur 1es barrages de retenues dans ltEmta (Unpu rt) BAtrAY, G. (1965) Recherche des gltes pr6-inaginaux de Simuliurn damnosum Theobald existant en a p6rlode de dEcrue dans 1e 1it princlpal de la Volta blanche (part,le Voltalque). Rapp. lnterne Centre Muraz 11 pp., 7 maps BALAY, G. (L967) Recherche des gltes pr6-imaginaux de Sinulium damnosum Theobald 1903 sur le r6seau hydrographique de la Volta rouge (partte Voltalque du cours) .Ra rt lnterne Centre Murazr9pp.r4naps BALAY, c. (1968) Bio-6co1og le des fenelles de S. damnosum Theobald 1903 dans les foyers dronchocercose de la Volta blanche, de la Vol-ta rouge et de la Sissili (R€publique de Haute-Volta). Rapp. interne Centre Muraz BARLET, P. (1962) La Haute-Volta. Essai de pr6sentation g6ographique. Etudes Voltalques, (3)z 5-77 BERNARD, Soeur Jean (Odette Pageard) (1965) Structures et relations sociales en Pays Bisa. Cahiers drEtudes Africalnes s(2) BERNARD, Soeur Jean (1966) Les Bisa du Cercle de Garango. Etudes Volt. (2)z 252 pp 3 Pl., 1 nap BOUTILLIER, J. L. (L964) Les structures fonciEres en Haute-Vo1ta. Etudes Volt., (5):128-138 cossELIN, c. (1964) Bibliographle g6n€r ale des Bisa. Etudes Volt. (5): 199-200 HUNTER, J. M. (1966) River blindness in Nangodl, Northern Ghana. A hypothesis of cyclical advance and retreat. Geogr. Rev. , LvI (3): 398-416 JONCHERE & PFISTER, R. (L952> Enqu8te sur la rEpartition de lfonchocercose en A.O.F. 8u11. Med. Afr. Occ. , 9(1): 5-2 KALOGA, B. (1966) Etude p6dologique des bassins versants des Volta blanche et rouge en Haute-Volta. Cah. ORSTOM ser. Pedol., 4(1): 23-6L LAGRAIILET, J. & AI"IMAN, F. (1961) Diff6rences draspect clinique de lronchocercose en Afrique noire selon 1a localisation gGographique. BuIl. Soc. Path. exot., 54(6)z L32O-L327 LAMONTELLERIE, M. (L964) Sinullum damnosr:m Theobald (Diptera, Simullidae) en zone de savane sEche (r6g1on de Garango, Haute-Volta). I. R6infestatlon de Ia Volta blanche en d6but de saison des pluies. 8u11. I.F.A.N. , {, S€rie A(4): 1298-1312 LAMONTELLERIE, M. (1965) Sinullum damnosum Theobald en zone de savane stsche (rEgion de Garango, Haute-Volta) (DiptEres, Simulildae). II. Infestatlon par Onchocerca volvulus Leuckart. BulI-. I.F.A.N 27, S6rle A(L): 2L9-228 a LE BERRE, R. (1966) Contribution I 1'6tude biologique et 6cologlq ue de Sinuliun damnosum Theobald 1903 (Diptera, Simuliidae . M6m O.R.S.T.O.M., No. L7, 2O4 pp., 38 figures, 3 plates LE BERRE, R. (L967) Possibilit6 et modalitEs de r6alisatlon drune canpagne r6glonale de lutte contre 1e vecteur de ltonchocercose. Rapp. lnt. Centre Muraz, 316/Oncho du 30-V-67, 9 pp. IrE BERRE, R., BALAY, c., BRENGUES, J. & COZ, J. (1964) Biologie et Ecologle de la fenelle de $inuliun damnosum Theobald , 1903 en fonctlon des zones bio-clinatiques de lrAfrique Qccidentale. Influence sur lr6pid6miologie de lronchocercose. Bull. Org. mond. Sant6, 31. 843-8s5 ocP/ 85 . 5 page 89 LEWTS, D. J. (1953) Sinuliuro damnosum and its relation to onchocerciasls in the Anglo--Egyp tian Sudan. Bull. ent. Res., 43:597-644 MONJUSIAU, A. (1965) Un essai de traitenent par Ia Not6zine B Sar6gou (Haute-Vo1ta). 5Eue Conf. Techn. 0.C.C.G.E. MONJUSIAU, A., LAGRAULET, J., D'HAUSSY, R. & GOEKEL' C . (1965) Aspects ophtalnol.ogiques de lronchocercose au Guatemala et en Afrique occidentale. Bull. Or . mond. Sant6 32(3): 339-3ss a OVAZZA, lq. Rapport sur une tourn6e pr6liminaire dans 1e secteur dtonchocercose du Cercle de Tenkodogo (Pays Bousenc6). Rapp . lnterne Centre Muraz , ovAzzA, yl., ovAzzA, L. & BALAY, G. (1965) Etude des populations de simuliun damnosum-Theobald 1903 (Dtptera, Simuliidae) en zone de gltes non perEanents. II. Variatlons saisonnlEres se produiffis-fGloffiations adultes et pr6imaginales. Discusslon des diff6rentes irypothEses qui peuvent expltquer le maintlen de ltespEce dans les r6glons sEches. Bul1. Soc. Path. exot., 58(5): 1118-1154 ovAzzA, M., R.ENARD, J. & BALAY, G. (1967) Etude des populatlons de Slmulluo dannosun Theobald 1903 Di tera Sinuliidae en zone de gltes non permanents. III. Correlatlon possible entre cer ns nes ologiques et la r6apparitlon des fenelles en d6but de saLson des p lules. Bull. Soc. Path. exot., 60(1)z 79-95 PHILIPPoN,B.(1968)Infestat1ondesfeme11esd"@P"r Onchocerca volvulus dans 1es conditlons naturelles en r6glon de savane. Rapp. lnterne Centre Muraz pHILIppON, B. & BALAY, c. (L967) Etude de Ia blologie et de lrecologle de S. damnosum Theobald I Ia lirnlte Nord de son alre de r6partitlon en Afrlque Occldentale; consEquences 6pld6nlologiques . M6d Afr. noire 14(10): 507-509 plIyUELO, R. (1949) Note prElimlnaire sur 1'onchocercose volvulaire Africaine en Pays Mossl- 6(2): 147-151 Bu11. l,led. de I'A.O.F. ' pl,IyUELO, R. & HOLSTEIN, M. (1950) Lronchocercose humalne en Afrique nolre frangalse, naladie sociale. M. Lecolnte ed. , Marsellles, 116 pp. ROLLAND, A. (1967) LtEpld6mlologie des I€sions oculalres caus6es par ltonchocercose dans le foyer de la Volta rouge. TEne Conf. Techn. O.C.C.G.E. ROLLAND, A. (1968) L'6pid6nlologie des l6sions oculalres causEes par lronchocercose en Ilaute-Volta. 8Bne Conf. Techn. O.C.C.G.E. RICHET, P. (1938) Lfonchocercose africaine ou volvulose (travall r6a1is6 dans le Cercle de Tenkodogo entre 1936 et 1938). RapPort ronEot.' 54 PP. RICHET, p. (1939) La volvulose dans un Cercle de C6te drlvoire. Les Eanlfestations cutanEes et oculatres. Bull. Soc. Path. exot. , 32(3): 341-355 RICHET, p. (7942) Volvulose et El6phantiasis. Observations recuelllles dans 1e foyer de trypanosomlase du Secteur annexe No. 15 (Tenkodogo - Haute-C6te drlvoire) . Bull. mens. s.G.H.tI.P. dfA.O. F. et Togo. 2, January and February VEILLEUX, M., LE BRETON, c., OLMAU & AUBRY, M. (1960) Archlves drophtalmologie, pp. 543-553 a WADDY, N. B. (1949) Onchocerciasis and blindness in the Northern TerritorLes of the Gold Coast. Unpubllshed report, Gold Coast Government, Mlnlstry of Health WANSON, M. (1950) Contribution d lr6tude de ltonchocercose humalne africaine (ProblEne de la prophylaxle d L6opoldville). Ann. Soc. belge Med. troP., 30: 667-83I I^IEGESA, P. (1966) Some factors influenclng the t,ransmisslon of onchocerca volvulus by Simulium woodi. Ann. rep. East Afr. Mal. Vec. borne Dls., pp. l4-L7 ,/. ocP/85.5 Page 90 AI.IONYMOUS. Nutritlonal survey of onchocerclasis foci ln Guatemala and West Africa, conpiled by the Parasltlc Diseases Unit, Divlslon of Comunicable Diseases, and Nutritlon Unit, Ilivision of Ilealth Protection and Promotion ANONYI.IOUS. Comit6 OMS drExperts de lfOnchocercose (1966) Org. mond. Sant. ser. Rapp. tech. 33s ANONY'I'!0US. Comptes-rendus de prospectlon du Secteur Mossi-Gourmantch6 (1939-1966). Archives Dlrectl0n Sant6 rurale llaute-Volta a - I t Do .Fl B () (Y) o\ c.t tt h ,-{ o E