The survival potential of Mycobacterium Bovis in secondary processed game meat

M. Tech. Environmental Health, Tshwane University of Technology, 2005.The Game Farming Industry in South Africa has progressed to, not only become a world leader in extensive sustainable utilization of game species, but has now tapped into the local and international meat market. Due to demand by inter alia, health conscious consumers, game meat has developed from being traditionally only eaten in the dried form i.e. biltong or dried wors, to a large number of game meat dishes in popular restaurants and game farm lodges. Although research was done on the health qualities of game meat, not much is known about possible zoonotic diseases when it is consumed. The well published and much talked about tuberculosis epidemic in all the National Parks, reserves, conservation areas and game farms suggested the ideal field for the research. Game meat from all the abovementioned areas is made available on the market for consumption. Therefore, the main reason for the study was to determine whether the causative organism for tuberculosis namely Mycobacterium bovis (M. bovis) can, when present, survive the secondary processing methods of cooking and drying. Lung, heart, lymph node, liver, kidney and muscle tissue from buffalo and kudu carcasses (n=14), identified to have tuberculosis were obtained from the Hluhluwe Umfolozi Park as part of their culling programme. These tissue samples were exposed to the cooking (n=672) and drying process (n=56) in a controlled environment in the tuberculosis laboratory at Onderstepoort Veterinary Institute. The cooked and dried samples were processed, incubated for 10 weeks and interpreted. Samples that showed growth typical of M. bovis, were further analysed by Polymerase Chain Reaction (PCR) to perform species conformation. Twenty three (23) of the slants obtained from samples exposed to the cooking process, showed growth while none of the slants obtained from samples exposed to drying showed any growth. One of the twenty three slants that showed growth was from kudu while the rest were from buffalo. None of the growth was confirmed as M. bovis when analysed by means of Polymerase Chain Reaction (PCR). The results showed that the cooking and drying process kills M. bovis when present. Game meat is safe for consumption, when properly cooked at adequate temperature and after sufficient length of time. Furthermore, biltong, derived from the drying process, (i.e. reduced water activity, lower hydrogen-ion concentration and an increased salt content), should be the preferred method of preparation as no growth whatsoever was observed. More growth was observed with buffalo than with kudu. The game industry should take the responsibility to inform and educate the public and commercial market of the best methods and practices to follow with processing and the possible dangers of consuming buffalo, an identified carrier animal of M. bovis