Risk of tuberculous infection in adolescents and adults in a rural community in Ethiopia.

BACKGROUND:The incidence of tuberculosis (TB) in sub-Saharan Africa is one of the highest in the world. OBJECTIVE:To evaluate the prevalence of TB, the annual risk of tuberculous infection (ARTI) and associated risk factors in rural Ethiopia. METHODS:A tuberculin skin test was performed among 2743 individuals in a rural community of Ethiopia around Ginci town, west of Addis Ababa, to estimate the prevalence of tuberculin reactivity and to assess factors associated with tuberculous infection. RESULTS:Among 2743 volunteer participants, test results were available for 2640, 691 (26.2%) of whom had an identifiable bacille Calmette-Guérin (BCG) scar; 221 (8.3%) reported household contact with a known TB case. The overall prevalence of TST reactions of ⩾ 10 mm was 29.7%. The ARTI was estimated at 1.7%. Tuberculin reactivity varied with age, sex, income and history of household contact with a TB case. Presence of BCG scar was not related to tuberculin reactivity. CONCLUSIONS:Our findings indicate that despite an effective TB control programme, TB transmission rates are still high in rural Ethiopia. Provision of isoniazid prophylaxis in close contacts of active TB cases among the poorest population groups may reduce TB incidence.