Prevalence of Tuberculosis Among Animals Selected from Slaughterhouses in Mbarara district, Uganda

Abstract

Tuberculosis (TB) is considered one of the most widespread infectious diseases and a leading cause of death and morbidity in both human and animal populations worldwide. The 2022 WHO global report ranked Uganda as a high burden TB country, with an estimated incidence of 198/100,000. The disease is caused by Mycobacterium tuberculosis complex, a group of seven species of the bacteria including Mycobacterium bovis the cause of bovine-type tuberculosis (bovine TB).  Mycobacterium bovis has a wide host range infecting cattle, goats, cats, dogs, buffalo, sheep, humans and wildlife. Slaughterhouses have been reported to be potential focus areas for public health monitoring. The aims of this study were to: 1) determine the effectiveness of slaughterhouses serving as active bio-surveillance centers for bovine TB and 2) determine the prevalence of TB among cattle, sheep and goats slaughtered at selected facilities. The sampling design was purposive, targeting Mbarara, a major cattle-producing district in Uganda. Also, Mbarara was accessible, as most of the country had restricted movement of people and animals due to the COVID-19 pandemic. Blood, lymph nodes and lung tissue samples were obtained from 29 cattle, 17 goats and 10 sheep from three slaughter facilities and tested using gross pathology and Ziehl-Neelsen (ZN) staining. The overall prevalence of Bovine TB, based on a positive lymph node or lung, was 8.9%% (5/56) and was higher in goats and sheep than cattle; In lymph nodes specifically, the TB prevalence was 3.4% (1/29) in cattle, 11.8%(2/17) in goats, and 10% (1/10) in sheep, whereas for lung tissue, it was 3.4% (1/29) in cattle and 17.6% (3/17) in goats; however, the difference was not statistically significant (p>0.05). Slaughterhouses could serve as active surveillance centers for important diseases such as bovine TB. However, additional control protocols may be warranted to reduce TB prevalence in the country.