Rates of tuberculosis transmission to children and adolescents in a community with a high prevalence of HIV infection among adults

Background. Tuberculin skin test surveys are routinely used to test for tuberculosis (TB) infection in communities, but there are few data from tuberculin skin test surveys from countries in which both TB and human immunodeficiency virus (HIV) infection are prevalent. Methods. We conducted a tuberculin skin test survey among 831 school-going children aged 5-17 years in a community that was experiencing an increase in the prevalence of TB and HIV infection. Responses to purified protein derivative RT23 were measured 3 days after the test was administered to determine tuberculin skin test results. Results. The prevalence of tuberculin skin test results positive for TB (i.e., an induration >= 10 mm in diameter in response to the skin test) ranged from 26.2% among children aged 5-8 years to 52.5% among children aged 14-17 years. The overall annual risk of infection was 4.1% using a 10-mm cutoff and 2.0% using a 17.4-mm cutoff. Annual risks of infection were constant across age groups. This is consistent with the finding that TB incidence remained the same in children (P = .48) from 1999 through 2005, although total TB incidence and adult TB (determined by sputum smear test) incidence increased in this community during the same period (P < .001). Conclusions. The annual risk of infection is high in the community. It appears that HIV infection-associated TB is not a major influence on the annual risk of infection and that TB transmission from adults to children may be associated with a subset of TB cases in the community. An improved understanding of TB transmission patterns is urgently needed help the implementation of novel strategies for reducing the annual risk of infection in this setting.