Trend in the incidence of smear-positive tuberculosis in a district in South India after DOTS implementation.

Abstract

One baseline and three repeat surveys of the prevalence of tuberculosis (TB) disease were conducted in 1999-2008 in rural South India, where the DOTS strategy was implemented in 1999. The impact of DOTS on prevalence was documented, but not its impact on incidence. To ascertain epidemiological trends in the incidence of smear-positive TB. All persons aged ⩾15 years (range 83 000-92 000) were examined using chest radiography (CXR); chest symptoms and history of anti-tuberculosis chemotherapy were noted in all four surveys. Sputum was collected from eligible participants and tested using direct smear and culture, and for drug susceptibility. As follow-up surveys were not frequent, survey cases and cases directly notified under DOTS were combined to estimate the incidence of smear-positive TB. Coverage was consistently high in all the repeat surveys, at ⩾80% for CXR and symptom recording, and at ⩾95% for sputum examination. The annual incidence of smear-positive TB was respectively 112, 80 and 76 per 100 000 population in 2001-2003, 2004-2006 and 2006-2008. The overall decline observed was 7.5% per annum. A well-implemented DOTS strategy can lead to a reduction in the TB burden in the community.