Does antiretroviral treatment increase the infectiousness of smear-positive pulmonary tuberculosis?

BACKGROUND: Understanding of the effects of human immunodeficiency virus (HIV) infection and antiretroviral treatment (ART) on Mycobacterium tuberculosis transmission dynamics remains limited. We undertook a cross-sectional study among household contacts of smear-positive pulmonary tuberculosis (TB) cases to assess the effect of established ART on the infectiousness of TB. METHOD: Prevalence of tuberculin skin test (TST) positivity was compared between contacts of index cases aged 2-10 years who were HIV-negative, HIV-positive but not on ART, on ART for < 1 year and on ART for >= 1 year. Random-effects logistic regression was used to take into account clustering within households. RESULTS : Prevalence of M. tuberculosis infection in contacts of HIV-negative patients, HIV-positive patients on ART >= 1 year and HIV-positive patients not on ART/on ART < 1 year index cases was respectively 44%, 21% and 22%. Compared to contacts of HIV-positive index cases not on ART or recently started on ART, the odds of TST positivity was similar in contacts of HIV-positive index cases on ART >= 1 year (adjusted OR [aOR] 1.0, 95% CI 0.3-3.7). The odds were 2.9 times higher in child contacts of HIV-negative index cases (aOR 2.9, 95% CI 1.0-8.2). CONCLUSIONS : We found no evidence that established ART increased the infectiousness of smear-positive, HIV-positive index cases.