Trend in Annual Risk of Tuberculous Infection in North India

SETTING: Six selected districts in Northern India. OBJECTIVES: To find out the trend in Annual risk of tuberculous infection (ARTI) in north India. STUDY DESIGN: Two rounds of community level surveys were conducted during 2000–2001 and 2009–10 respectively. Representative samples of children 1–9 years of age were tuberculin tested and maximum transverse diameter of induration was recorded in mm at about 72 hours. ARTI was computed from the estimated Prevalence of infection using mirror-image technique and anti-mode method. RESULTS: ARTI was found to decline from 1.9% (confidence interval: 1.7–2.1) at round I to 1.1% (confidence interval: 0.8–1.3) at round II at the rate of 8% per year during the intervening period. CONCLUSION: A significant reduction in the risk of tuberculous infection among children was observed between two rounds of surveys carried out at an interval of about 9 years.