Reconstructing a Tuberculosis Exposure Network in a Vulnerable Urban Community: a Field Epidemiological Investigation in Southern Brazil

Abstract Background/Objective In urban communities marked by social and environmental vulnerabilities, poor housing conditions and difficulties in accessing and maintaining healthcare may favor repeated exposure to Mycobacterium tuberculosis and hinder interruption of transmission. This study aimed to describe an epidemiological and social tuberculosis exposure network reconstructed after notification of a tuberculosis disease case in Southern Brazil, incorporating previous cases that had remained dispersed across records and unrecognized as part of the same community network. Methods A descriptive observational study analyzed data generated during a routine field epidemiological investigation conducted from the first half of 2025 to February 2026. Epidemiological and social links were reconstructed through active case finding, community follow-up, and review of healthcare and surveillance records. The study population comprised 43 people: 38 identified during the current investigation and five previous tuberculosis disease cases retrieved from records. Results Among the 43 people, 15 had tuberculosis infection, four were newly diagnosed with tuberculosis disease, five had previous tuberculosis disease, 18 had no evidence of infection or disease at the last available assessment, and one was not assessed. Overall, 24/43 (55.8%) had tuberculosis infection or a current or previous diagnosis of tuberculosis disease. Conclusions Community-based active case finding and territorial follow-up enabled reconstruction of a network connecting different tuberculosis-related events within the same community. Although a continuous transmission chain could not be established, the findings indicate persistent tuberculosis-related events and reinforce the need for territorial surveillance strategies that recognize community specificities, integrate care and surveillance, and sustain follow-up where people live.