Retrospective epidemiological surveillance of bovine tuberculosis in a slaughterhouse in Northeastern Brazil

Bovine tuberculosis (BTB), mainly caused by Mycobacterium bovis, remains an endemic zoonosis with significant economic and public health impact, particularly in major beef-producing countries such as Brazil. This study aimed to evaluate the occurrence, epidemiological profile, and macroscopic features of BTB-like lesions identified during routine post-mortem inspection at an officially inspected slaughterhouse in Northeastern Brazil over a six-year period (2020–2025). A retrospective observational study was conducted based on official inspection records from 79,318 slaughtered cattle. Thirty-six carcasses were totally condemned due to lesions suggestive of BTB, corresponding to an overall prevalence of 0.045% (95% CI: 0.032–0.063%), with no significant temporal trend throughout the study period. Affected animals were predominantly females (61.1%), who presented significantly higher odds of condemnation compared to males (OR = 5.76; 95% CI: 2.92–11.37; p < 0.001), and animals older than 36 months (75%). Macroscopically, lesions were mainly granulomatous, with caseous necrosis and calcification, primarily involving the lungs, mediastinal lymph nodes, and liver, indicating chronic and frequently systemic infection. Despite the low apparent prevalence, the consistent annual detection of advanced lesions suggests sustained endemic circulation of agents compatible with bovine tuberculosis within source herds. These findings reinforce the epidemiological value of slaughterhouse surveillance as a complementary, cost-effective tool for BTB monitoring, contributing to risk assessment, guiding herd-level control strategies, and strengthening integrated actions within a One Health framework.