Wildlife Tuberculosis Study Group

Transmission of the live M bovis organism is believed to occur mainly via aerosolized droplets from a coughing or sneezing animal with open pulmonary tuberculosis. The period of infectiousness may be extremely long and the carrier may transmit disease for several months or even years. The feeding of infected carcasses to animals may also lead to transmission of disease.

Although originally believed to be a disease of domestic cattle in Europe, the disease was spread to other continents when domestic cattle were exported all over the world during the colonial era. The success of disease’s spread and survival of the pathogen can be ascribed to the fact that most species worldwide are susceptible to Mycobacterium bovis.

The most important factors determining the spread of disease are the number of infected individuals and the number of young animals exposed to infected individuals. Possible routes of infection with Mycobacterium bovis include respiratory, alimentary, congenital, cutaneous, venereal and via the teat canal.

In certain species the infection can sustain itself within the host population by reinfection of the same species. These species are called maintenance hosts and play an important role in the spread of the disease. Other species that get infected but do not sustain the infection within their population are called spill-over hosts.

On the African continent and specifically in southern Africa, the disease has been diagnosed in a variety of animal species. The first cases of BTB in free-living wildlife populations were reported in kudu (Tragelaphus strepsiceros) and duiker (Sylvicapra grimmia) from the eastern Cape province during the early 1900’s. After the diagnosis of BTB in a buffalo from the KNP in 1990, the disease has since been confirmed in the Kruger National Park and surrounding areas in the following species:

• Buffalo (Syncerus caffer)
• Kudu (Tragelaphus strepsiceros)
• Eland (Taurotragus oryx)
• Impala (Aepyceros melampus)
• Warthog (Phacochoerus aethiopicus)
• Bushpig (Potamochoerus porcus)
• Baboon (Papio ursinus)
• Lion (Panthera leo)
• Leopard (Panthera pardus)
• Cheetah (Acinonyx jubatus)
• Large spotted genet (Genetta trigrina)
• Hyena (Crocuta crocuta)
• Honey badger (Mellivora capensis)

Bovine tuberculosis has been diagnosed in buffaloes, kudu and lions in the Hluhluwe Imfolozi conservation areas of Kwazulu-Natal. In the rest of Africa BTB has been confirmed in the lechwe (Kobus lechwe) population of Zambia, as well as buffaloes and warthogs from the Rwenzori National Park in Uganda. The wildbeest and lion populations of Tanzania is also believed to be infected with BTB.