Tuberculin survey in Bangladesh, 2007-2009: prevalence of tuberculous infection and implications for TB control

OBJECTIVES: To assess the prevalence of tuberculous infection and the annual risk of tuberculous infection (ARTI) for 2007-2009 in Bangladesh, approximately 45 years after the first tuberculin survey in 1964-1966. METHODS: A tuberculin survey was conducted along with the National Tuberculosis Disease Prevalence Survey in 2007-2009. This was a multistaged community-based, cross-sectional survey, including 17718 children aged 5-14 years. The prevalence of tuberculous infection was estimated using the mixture method and a cutoff point of 8 mm. RESULTS: The prevalence of infection was 10.0% (interquartile range [IQR] 8.6-12.2) in children aged 5-9 years and 17.9% (IQR 15.4-20.2) in those aged 10-14 years using the mixture analysis. Prevalence was 12.4% (95% confidence interval [CI] 11.7-13.1) in children aged 5-9 years and 22.6% (95%CI 21.6-23.4) in those aged 10-14 years using a cut-off point of 8 mm. The estimated ARTI was respectively 1.5% and 1.7% in 5-9 and 10-14 year olds using the mixture method and respectively 1.9% and 2.1% using the cut-off method. CONCLUSIONS: The moderate reduction in the prevalence of infection and slow decline of the ARTI after two decades of DOTS implementation indicates considerable ongoing transmission.