Setting: Rural and urban areas of six selected districts in the western zone of India.
Objectives: To estimate the annual risk of tuberculous infection (ARI).
Design: A community-based, cross-sectional tuberculin survey was conducted among children aged 1-9 years residing in a sample of rural and urban areas of six districts in the western zone of India. Stratified two-stage cluster sampling was adopted for selection of rural and urban clusters. A total of 48473 children in 600 clusters underwent tuberculin testing with 1TU PPD RT23 with Tween 80; the induration was measured about 72 h after the test.
Results: The BCG scar was observed in 52% of the test-read children. Estimation of the prevalence of infection was based on the frequency distribution of tuberculin reaction size among 22259 children without BCG scar. Reactions > or = 15 mm were considered attributable to infection with tubercle bacilli. The prevalence of infection was estimated to be 9.3%, and the ARI computed from the estimated prevalence was 1.8%. The proportion of infected children was found to be significantly higher in urban than in rural areas.
Conclusion: The high rate of ARI in the western zone of India calls for further intensification of tuberculosis control efforts.