Area for Tuberculosis Control

Assessment of Community Infection Ratio in the r "Model DOTS Project" area for Tuberculosis Control P. Paul Kumaran Dissertation submitted in partial fulfilment of the requirements for the award of the degree of Master of Public Health Achutha Menon Centre for Health Science Studies Sree Chitra Tirunal Institute for Medical Sciences and Technology Thiruvananthapuram, Kerala, India. June 2002 DECLARATION I hereby certify that the work embodied in this dissertation entitled "Assessment of Community Infection Ratio in the 'Model DOTS Project' area for Tuberculosis Control" is the result of original research and has not been submitted for any degree in any other University / Institution. is\v4"2- Dr.P.Paul Kumaran Place: Thiruvananthapuram, Kerala Date: I (kA a-10 ii CERTIFICATE Certified that the dissertation titled "Assessment of Community Infection Ratio in the 'Model DOTS Project' area for Tuberculosis Control" is a bonafide record of original research work undertaken by Dr P Paul Kumaran in partial fulfillment of the requirement for the award of the Master of Public Health degree under our guidance and supervision. Co-Guide Guide Dr Aleyamma Thomas Dr K R Thankappan Deputy Director (Sr Gr) Associate Professor & acting HOD Tuberculosis Research Centre (ICMR) AMCHSS, SCTIMST • Chennai, Tamil Nadu, India Thiruvananthapuram, Kerala, India iii ACKNOWLEDGEMENTS At the outset, I would like to express my heartfelt thanks to Prof Arthur L Reingold, Professor of Epidemiology, School of Public Health, University of California, Berkeley, CA, for enlightening me about the concept of 'community infection ratio for tuberculosis control', and I dedicate this piece of work to him. My sincere thanks are also due to him for his healthy and constructive criticism in improving the methodology of my study. I take this opportunity to thank Dr P R Narayanan, Director, Tuberculosis Research Centre for his whole hearted and constant support, which enabled to undertake and complete the study in due time without any hindrances. I thank Prof Richard A Cash from Harvard School of Public Health, Boston, USA, Dr Thomas R Frieden, Dr Reuben Swamickan and Dr Alka Aggarwal Singh, Programme Medical Officers for Tuberculosis Control, WHO-SEARO and WHO-India, and Dr V Mohanan Nair, Dr R Sukanya, Mrs Shiney C Alex and Mrs Betty Susan Ninan from AMCHSS for their valuable guidance during the planning process of my study. My sincere thanks are due to Mr R Subramani and Mr P G Gopi, TRC, who helped me in planning the execution of the data collection process. My special thanks are due to Mr S Janakiraman and Mr K S Venkatesan, TRC, who were with me through out the data collection period and helped me in all possible ways for its successful completion. I would like to thank Dr P Sankara Sarnia, AMCHSS, for his talented advice regarding statistical analysis. I will be failing in my duty if I do not acknowledge Dr K R Thankappan, AMCHSS, and Dr Aleyamma Thomas, TRC, my guide and co-guide, who traveled along with me through the whole stretch of this research piece of work. Last, but not the least, I like to thank the Almighty for blessing and guiding me throughout my life and for making this research possible. I' Paul Kumaran iV It1111 01111RIIIIE CONTENTS I. Introduction 2 - 4 2. Review of literature 5 - 12 a. Epidemiology of tuberculosis 6 b. Tuberculosis infection 7 c. Control of tuberculosis 8 d. Identification of tuberculosis infection 9 e. Revised National Tuberculosis Control Programme 10 f. Assessment of Community Infection Ratio 1 I 3. Aim and Objectives of the study 13 - 14 4. Methodology 15 - 23 a. Study population 16 b. Study area and sampling frame 17 c. Contact-Control household definition 17 d. Sample size 17 e. Methods 20 f. Data entry and analysis 22 g. Definitions of parameters used during analysis 22 h. Calculation of Community Infection Ratio 23 5. Results 24 - 39 a. Interpretation of tuberculin skin test 28 b. Community Infection Ratio 37 6. Discussion 40 - 43 7. Conclusion 44 - 45 8. References 46 - 49 9. Appendix 50 - 56 a. Annexure 1: Form for Contact households 51 b. Annexure 2: Form for Control households 52 c. Annexure 3: Work instructions for filling the forms 53 d. Map I : Geographical position of Tiruvallur district 54 e. Map 2: Tuberculosis Units in Tiruvallur district 55 f. Map 3: Tiruvallur — Model DOTS Project area 56 LIST OF TABLES AND FIGURES 1. Table 1: Disease survey and tuberculin survey villages (with NSS+ve cases and children less than 15 years): Baseline — Model DOTS Project area — TRC. 18 - 19 2. Table 2: Frequency distribution of household characteristics of the study population ... 26 3. Table 3: Frequency distribution of the baseline characteristics of children 27 4. Table 4: Frequency distribution of the baseline characteristics of contact cases 29 5. Table 5: Mean distribution of the baseline characteristics of the study population 30 6. Table 6: Distribution of tuberculin skin test results by household characteristics • • - 32 7. Table 7: Distribution of tuberculin skin test results by characteristics of children 34 8. Table 8: Distribution of tuberculin skin test results by characteristics of contact cases 35 9. Table 9: Mean distribution of tuberculin skin test results of the study population ... 36 10. Table 10: Risk factors associated with tuberculin skin test positivity (Univariate analysis) • ,• 38 11. Figure 1: Frequency distribution of tuberculin test reading among the study population 31 vi dedicaled t6 Arthur aang-old fir Introducing- the concept of Foinniunitg, o7nfiction 6Qatio 1 assessment of 6ommunO9njeretion) aa-tio in the i'Modela0("C'33 Z'reject' areafir (nbercularir ontre,/ o7ntroduction... 2 Assessment of community infection ratio in the Model DGIS Project area lor tuberculosis control INTRODUCTION It is more than two millennia since humankind saw tuberculosis and more than a century since Sir Robert Koch discovered Mycobacterium tuberculosis as the causative organism, the magnitude of the global tuberculosis problem is still expanding. It continues to be a stigmatized disease and a major public health problem. It is estimated that, globally, one in three persons alive today is infected with the tubercle bacilli 1 , that there are more than 8 million new cases of active tuberculosis and about 3 million deaths per year 2, making tuberculosis the leading etiological agent among lethal infectious diseases for adults in the world. Tuberculosis is responsible for 5% of all deaths worldwide and 9.6% of adult deaths between 15 and 59 years of age 3. The global burden of disease study, initiated in 1992 at the request of the World Bank for use in its 1993 World Development Report 4, has estimated an increase in the disability adjusted life years for tuberculosis worldwide from 38.4 million in 1990 to 42.5 million in 2020 5. The reemergence of tuberculosis in countries where it was under control, the advent of human immunodeficiency virus--HIV that is likely to increase the burden of tuberculosis, and the emergence of drug resistant tuberculosis forced the World Health Organization to declare tuberculosis as a global emergency in 1993. In India, tuberculosis is the single leading infectious killer disease and it has more cases of tuberculosis than any other country in the world. Though India's population is 3 Assessment nl community mreetion ratio in the Motitl S l'fuject area !or luberculusts control R• only about 16% of the world's total *, it contributes to 30% of the world's tuberculosis 6 cases . Every year, 2 million people develop the disease and nearly 5 lakhs die from it - more than 1000 every day '. The disease prevalence is about 8 per thousand (4 per 1000 bacteriologically positive tuberculosis cases and another 4 per thousand bacteriologically negative but radiologically positive cases) 8. About 50% to 60% of the nation's population is infected with tuberculosis 9 and the annual risk of tuberculosis infection ranges between 1% and 2% 8. Furthermore, tuberculosis is a major barrier to economic development, costing India approximately Rs.12,000 crore (USS 3 billion) a year 7. It has devastating social costs as well; data suggests that each year, more than 300,000 children are forced to leave school because their parents have tuberculosis, and more than 100,000 women with tuberculosis are rejected by their families 7. The world's population is 6,137 million [mid 2001] (Ref ht 2://www.census.gol) and that of India is 1,027 million [2001] (Ref. Provisional population totals: India. Census of India 2001, Series 1, India, Paper 1 of 2001), 4 Assessment (y-Fommunio) c7n1ction Catio rrl the 11 /(odel L- rcyccen areafir tuberculoses Fontrol Certor o ll'oraturc... 5 AStiCtiS111(71111. t 1 eur Inuuniy LaCc(1011 ran in MOtlel 00.1S Pt.ujec urea fot 11.11/creLLIOSIS Condit)] 4 REVIEW OF LITERATURE EPIDEMIOLOGY OF TUBERCULOSIS To facilitate understanding of the relevance of epidemiology in implementing a successful control programme, the study of a model following the pathogenesis of tuberculosis in humans, from exposure to cure or death, is useful. Mycobacterium tuberculosis is most commonly transmitted from a patient with infectious pulmonary tuberculosis to another person through droplet nuclei. Exposure to a potentially infectious case is a prerequisite for becoming infected. The risk factors for becoming exposed include the number of incident tuberculosis infectious cases in the community, the number of case-contact interactions per unit time, the degree and duration of infectiousness of the case and the shared environment of the contact case 10. Once an individual is exposed, the airborne transmission of the infectious droplet nuclei, ventilation and host immune response are some of the factors that determine the risk of becoming infected 1°. Thus, the risk of acquiring tuberculosis infection is determined mainly by exogenous factors.

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