The etiology and public health significance of mycobacteriosis of cattle in Kenya

Background: Zoonotic tuberculosis, commonly referred to as bovine, tuberculosis is mainly caused by Mycobacterium bovis subsp. bovis, a member of the mycobacterium tuberculosis complex (MTBC). Infection in humans resembles that caused by Mycobacterium tuberculosis. Mycobacteria Other Than Tuberculous (MOTTs) are also increasingly being associated with tuberculosis humans but reports of infections in animals are scarce, their zoonotic potential being largely ignored. The study aimed to determine the aetiology and public health importance of mycobacteriosis in slaughter cattle in Kenya. Methods: Routine postmortem meat inspection was performed on a subpopulation of 1000 meat carcasses selected randomly from among 7,564 in a municipal abattoir, between January and July, 2015. Carcasses were examined for tuberculous lesions which were then examined for acid-fast bacilli, (AFB), cultured for isolation of mycobacteria and the isolates characterized by DNA analysis. Results: Of the carcasses examined, 218 (21.8%) had lesions in various parts of the carcasses. Acid-fast bacilli were observed in 63/218 of the lesions and suspected mycobacteria isolated from 35 of them. The isolates were identified as M. fortuitum (12), M. bovis subsp. bovis (3), M. shimoidei (2) M. asciaticum, M. interjectuctum, M. szulgai, M. celatum and M. kansaasii at one (1) each. Thirteen (13) of the isolates could not be speciated. Conclusion: The MOTTs identified in the study have been liked to various types of mycobacteriosis in humans. The study therefore highlights the pathogenic and zoonotic potential of MOTTs, indicating that zoonotic tuberculosis should not be restricted to Mycobacterium bovis subsp.bovis