Mycobacterium bovis in humans and M. tuberculosis in animals in Nigeria: an overview from 1975-2014

Zoonotic transmission of mycobacteria between humans and other animal species is an important aspect of the epidemiology of tuberculosis (TB) in regions of the world where the burden of the disease in humans and other animals is high. This is particularly important in areas in which sociocultural factors increase the possibility for interspecies transmission of different mycobacteria. Carrying out a review of the published literature involving laboratory-confirmed TB cases (by culture) and/or biochemical and molecular identification, we described the presence of Mycobacterium bovis and M. tuberculosis infections in humans and animals from 1975 to 2014. Overall, 1693 isolates of M. tuberculosis complex and other mycobacteria were identified and reported, of which 1131 represented M. tuberculosis, 286 represented M. bovis, 71 represented M. africanum, and 205 represented other mycobacteria. Importantly, 1.3% (15/1131) of the M. tuberculosis isolates reported were identified in cattle, while 8.0% (23/286) of the M. bovis isolates reported were isolated from humans. We suggest that representative sampling of TB cases in both hosts, studied by molecular identification tools, will help significantly in deciphering ongoing transmission between animals and humans in both directions and will enhance TB control in Nigeria.