Incidence of smear-positive pulmonary tuberculosis from 1981-83 in a rural area under an active health care programme in south India

Abstract

Setting: Four villages in the K V Kuppam Block of North Arcot Ambedkar District, Tamil Nadu, south India.

Objective: To determine the prevalence and incidence of microscopy positive patients with pulmonary tuberculosis.

Design: The entire population of 22,847 was covered prospectively; the prevalence survey in 1981 was conducted through house to house interviews followed by collecting and examining sputum specimens by microscopy from symptomatic patients (cough for more than 2 weeks duration or other respiratory or systemic symptoms compatible with tuberculosis). The prevalence survey was followed by monthly visits for two consecutive years to obtain an accurate estimate of the incidence.

Results: The prevalence in the population among persons aged 10 years and above was 2.41 per 1000, the average annual incidence during 1981-83 was 1.11 per 1000 or 46% of the prevalence. The male:female ratio in the prevalence survey was 2.6:1, while in the incidence assessment it was 2.4:1.

Conclusion: The results of the study provide valuable information on the relation between prevalence and incidence of sputum smear-positive cases which should help to better our understanding of the epidemiology of tuberculosis in a disadvantaged part of the world. The reliable estimate of incidence of the microscopy positive cases provided by the study should be very useful for assessing the efficacy of case finding in the District Tuberculosis Programme in India.