Prevalence and Molecular Characterization of MTBC at the Human-Livestock Interface Across Five Regions of Tanzania

Objective: Zoonotic tuberculosis (TB) caused by members of the Mycobacterium tuberculosis complex (MTBC) remains an important but under-recognized public health concern in settings where humans and livestock closely interact. Although TB transmission is well documented in Tanzania, limited molecular evidence directly linking livestock infections to human cases leaves uncertainty regarding the extent of cross-species and reverse-zoonotic transmission. This study assessed the prevalence, species distribution, and potential interspecies transmission of MTBC among livestock and humans across five regions of Tanzania. Methods: A total of 132 post-mortem livestock samples and 101 human samples were analyzed using polymerase chain reaction (PCR) for MTBC detection and species differentiation. Results: The MTBC detection rate in livestock was 2.3%, with all positive cases identified in cattle. Among humans, MTBC positivity was 20.8% and occurred primarily among adults aged 35–54 years. Human immunodeficiency virus (HIV) infection and a history of TB were strongly associated with MTBC positivity (p<0.001), whereas exposures such as consumption of unpasteurized milk, livestock contact, and household ventilation showed no significant associations. Conclusions: The findings suggest ongoing MTBC circulation at the human–livestock interface and potential zoonotic transmission risk. Strengthened One Health surveillance is recommended to mitigate zoonotic and reverse-zoonotic TB transmission in Tanzania.