Prevalence of tuberculosis among southern Zambian cattle and isolation of Mycobacterium bovis in raw milk obtained from tuberculin positive cows

Aim: To determine the prevalence of tuberculosis among traditional milking cows in southern Zambia and isolation of Mycobacterium spp from the tuberculin positive cow's milk. Materials and Methods: A total of 1,025 cows originating from traditional cattle sector, in Mapepe, Magoye, Monze, Batoka, GARTBatoka, Kalomo areas of Zambia, supplying major quantity of milk to milk processors, were tested for bovine tuberculosis using single comparative intra-dermal tuberculin test during 2011 and 2012. Milk samples obtained from 16 bovine tuberculin reactor cows were cultured for isolation of Mycobacterium spp and those showing growth of Mycobacterium spp. were identified through biochemical tests of the culture. Further confirmation and species differentiation of the Mycobacterium spp. isolates was done using the loop-mediated isothermal amplification system and multiplexpolymerase chain reaction Results: 27 (2.6%) of the cows tested were found tuberculin reactors, 9 cows (0.87 %) gave inconclusive reaction and 989 (96.48%) were non-reactors. Three milk samples (18.7%) out of the 16 tuberculin reactor cow's milk when cultured and upon molecular analysis, were found positive for presence of M. bovis indicating these positive cows were shedding M. bovis in their milk. Conclusion: The isolation of M. bovis in freshly drawn milk from the tuberculin positive reactor cows is being reported for the first time in Zambia. Bovine tuberculosis is an animal and human health risk in the traditional dairy herds supplying milk to the Zambian population especially in the informal market and needs attention of the public health and veterinary authorities.