Epidemiology of active tuberculosis among adult household contacts of patients with smear-positive pulmonary tuberculosis in Kembata-Tembaro zone, southern Ethiopia: a cross-sectional study

Background The risk of tuberculosis transmission is higher among household contacts than the general population. However, there is a paucity of information that explains the risk of experiencing active tuberculosis among household contacts in countries with a high burden of tuberculosis. Objective This study aimed to assess the prevalence of tuberculosis infection and associated factors among adult household contacts of smear-positive pulmonary tuberculosis patients in the Kembata-Tembaro zone, southern Ethiopia. Methods A cross-sectional study design was conducted in the Kembata-Tembaro zone, southern Ethiopia, from August to September 2022. Data were collected from 336 adult household contacts using a pretested questionnaire, and sputum examinations were done using fluorescence microscopy. Binary logistic regression models were used to identify factors associated with tuberculosis infection among adult household contacts. Results The prevalence of active tuberculosis among adult household contacts of smear-positive pulmonary tuberculosis patients was 6.9% (95% CI 4% to 10%). Nearly half, 47.8%, of them belonged to economically productive adults aged 30–44 years. Smoking cigarettes (adjusted OR (AOR) 6.5, 95% CI (1.04 to 40.17)), sharing a bed with the index tuberculosis case (AOR 6.0, 95% CI (1.97 to 18.28)), poor housing ventilation (AOR 4.2, 95% CI (2.85 to 17.16)) and overcrowded housing (AOR 4.6, 95% CI (1.42 to 14.58)) were associated with tuberculosis infection among household contacts of patients with smear-positive pulmonary tuberculosis. Conclusions This study has revealed that the prevalence of active tuberculosis among adult household contacts of smear-positive pulmonary tuberculosis patients was detected to be similar to other reports from Ethiopia. Additionally, interventions to prevent tuberculosis transmission among household contacts should focus on providing behaviour change education, improving housing conditions, early detection and isolation of index cases, contact tracing, isoniazid chemoprophylaxis of household contacts with weakened immunity and covering the mouth and nose when coughing or sneezing.