Trends in the annual risk of tuberculous infection in India .

Chadha, V.K.; Sarin, R.; Narang, P.; John, K.R.; Chopra, K.K.; Jitendra, R.; Mendiratta, D.K.; Vohra, V.; Shashidhara, A.N.; Muniraj, G.; Gopi, P.G.; Kumar, P.

International Journal of Tuberculosis and Lung Disease; 2013; 17; 312-319.

Summary: Setting: Twenty-four districts in India .

Objectives: To evaluate trends in annual risk of tuberculous infection (ARTI) in each of four geographically defined zones in the country.

Study design: Two rounds of house-based tuberculin surveys were conducted 8–9 years apart among children aged 1–9 years in statistically selected clusters during 2000–2003 and 2009–2010 (Surveys I and II). Altogether, 184992 children were tested with 1 tuberculin unit (TU) of purified protein derivative (PPD) RT23 with Tween 80 in Survey I and 69496 children with 2TU dose of PPD in Survey II. The maximum transverse diameter of induration was measured about 72 h after test administration. ARTI was computed from the prevalence of infection estimated using the mirror-image method.

Results: Estimated ARTI rates in different zones varied between 1.1% and 1.9% in Survey I and 0.6% and 1.2% in Survey II. The ARTI declined by respectively 6.1% and 11.7% per year in the north and west zones; no decline was observed in the south and east zones. National level estimates were respectively 1.5% and 1.0%, with a decline of 4.5% per year in the intervening period.

Conclusion : Although a decline in ARTI was observed in two of the four zones and at national level, the current ARTI of about 1% in three zones suggests that further intensification of TB control activities is required.

Keywords: T uberculosis; infection; risk; trends; India

Back to List of publications / Home