Incidence of smear-positive tuberculosis in Dabat, northern Ethiopia

Abstract

To determine the incidence of smear-positive tuberculosis (TB) in Dabat District, northern Ethiopia. Using a population-based longitudinal design, a TB surveillance system was initiated among 46,165 residents at the Dabat Health and Demographic Surveillance System site. Trained field workers visited each household every third month and interviewed all individuals aged ≥14 years using a uniform questionnaire to detect suspected cases of TB (cough ≥15 days), at which time two sputum (spot-morning) samples were collected for smear microscopy. A total of 281,820 person-months were observed during the 1-year period, which generated 74 smear-positive TB cases. The incidence of smear-positive TB was calculated at 311 per 100,000 person-years (95%CI 240-382). Higher rates were observed among females (incidence rate ratio [IRR] 2.08, 95%CI 1.24-3.52), persons with no schooling (IRR 2.74, 95%CI 1.11-6.78) and urban residents (IRR 2.39, 95%CI 1.39-4.12). The incidence of smear-positive TB is high in Dabat District, suggesting a high risk of transmission in the communities. TB control programmes thus need to improve case-finding mechanisms at the community level in Ethiopia, with greater emphasis on risk groups.