Two-thirds of smear-positive tuberculosis cases in the community were undiagnosed in Northwest Ethiopia: population based cross-sectional study.

BACKGROUND: Tuberculosis (TB) case detection rate remains low in Ethiopia. One of the underlying reasons is the emphasis on passive case finding strategy which may seriously underestimate the burden of the disease. Estimating the prevalence of smear-positive pulmonary TB through active case finding at population level can help assessing the degree to which passive case detection is successful.

METHODS AND FINDINGS: This is population based cross-sectional study. The study population was all individuals aged ≥14 years. Interviews using a uniform questionnaire were done initially to identify individuals with chronic cough (≥15 days) and the two sputum (spot and morning) samples were gathered for standard smear microscopy. A total of 23,590 individuals aged ≥14 years were interviewed and 984 had a chronic cough for ≥15 days. Of 831 individuals who provided two sputum samples for acid fast bacilli (AFB), 41 had positive smears. A total of 22 smear-positive TB cases detected through passive case finding were on anti-TB treatment. The prevalence of new smear-positive TB was 174 per 100,000 in persons aged ≥14 years (95% CI: 121-227).The ratio of active to passive case finding was 2:1. Higher rates of smear-positivity were observed among females [AOR: 3.28, 95% CI (1.54-6.77)], and in the age group ≥45 years [AOR: 2.26, 95% CI (1.12-4.59).

CONCLUSIONS: The study revealed that about two-thirds of patients with active TB remain undiagnosed and thus untreated. This may indicate the need for strengthening case detection at the community level. Furthermore, the high burden of TB among females and in the age group ≥45 years warrants appropriate measures to control the disease.