BTB in Wildlife in Africa

There is a large and diverse, but dwindling, population of wildlife species in Africa, most of which are likely to be susceptible to M. bovis infections. However, with few exceptions, throughout the years, no attention was given to whether they were infected or to what extent they played a role in the epidemiology of the disease in the different countries on the continent.

Bovine TB has now been diagnosed in a range of African wild mammalian species (antelopes, omnivores, primates, and predators), which, depending on the circumstances, can be either maintenance or spillover hosts for M. bovis, and they constitute a source of infection for cattle and other susceptible species. The African continent, with its high densities of mammals, large cattle populations, and poorly resourced veterinary services, presents ideal circumstances for the bidirectional spread of M. bovis at the interface between cattle and wildlife populations as has been seen in a number of protected conservation areas in sub-Saharan Africa.

Reports dealing with BTB in wildlife over the years were few and far between. In African wildlife, BTB was first diagnosed during the 1920s in greater kudus (Tragelaphus strepsiceros) and a few other wildlife species during a destructive outbreak of the disease in South Africa (Paine and Martinaglia 1929). Further cases of BTB in wildlife were only reported in the 1960s when the disease was diagnosed in 13 free-ranging African buffaloes (Syncerus caffer) in a game park in Uganda (Guilbride et al.

It was only after the disease was diagnosed in the Kruger National Park that more attention was given to the infection in wildlife, because of the role that some of them play as maintenance hosts and the impact on ecosystems in the long term. Following this event, the South African Veterinary Services developed a comprehensive protocol, the Veterinary Procedural Notice for Buffalo Disease Risk Management in South Africa (also referred to as the Buffalo Veterinary Procedural Notice), to regulate the movement of buffaloes in the country and to manage the risk posed by BTB-infected buffaloes to cattle that may come in contact with them (DAFF 2017). (For further information about BTB in wildlife see Chap. 5.)

It is clear that local BTB-infected cattle were the source of the infection for the lechwe in Zambia (Macadam et al. 1974) and the buffalo populations in the Kruger National Park (KNP) (Rodwell et al. 2001) and the Hluhluwe-iMfolozi game reserves in South Africa (Jolles et al. 2005), and it is likely that this situation prevails in other countries in which there is close contact and intermingling of cattle and infected wildlife. Following local investigations in South Africa, it appears that M. bovis can survive in the harsh African environment for up to 6 weeks in winter and up to 4 weeks under favorable conditions during the rest of the year (Tanner and Michel 1999). Infected wildlife species are thus another source of infection causing environmental contamination that is an important source of infection for a number of wildlife species, all scavengers, including chacma baboons (Papio ursinus), banded mongooses (Mungos mungo), and warthogs (Phacocoerus africanus) (Bruns et al. 2017).

Even a relatively low prevalence of the disease in any wildlife population may pose a substantial health risk to other wildlife species (particularly predators and scavengers) and domestic animals at the interface with infected wildlife. In this context, BTB caused by M. bovis is a regional threat, particularly at the human­livestock-wildlife interface in Africa, and it should always be kept in mind when attempting to control the disease in cattle.

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