"Impacts of Wildlife Infections on Human and Livestock Health with Special Reference to Tanzania: Implications for Protected Area Management"

Sarah Cleaveland, Karen Laurenson, Titus Mlengeya

Microbial pathogens are integral components of natural ecosystems and play an important role in the evolution and ecology of host communities. However, the growth of human population and expansion of human activities has affected contact and transmission patterns between human and animal populations, leading to the emergence of several major diseases that affect human health, livestock economies and wildlife conservation.

Zoonotic pathogens, particularly those that infect wildlife, pose a particular risk for human disease emergence (relative risk for zoonoses = 1.97; for pathogens infecting wildlife =2.44). Zoonotic diseases associated with wildlife, such as sleeping sickness and anthrax, also pose a potential threat to the tourist sector, which is a major source of foreign exchange in many African countries. Wild animal populations are often implicated as reservoirs of emerging zoonoses, but we have little knowledge of the infection dynamics of these diseases in wildlife, which limits the options and effectiveness of disease control.

Infections in wildlife also have major implications for livestock development in areas adjacent to wildlife (protected) areas. Most livestock pathogens (54%) can also co-infect wildlife. Where wild populations are the source of disease for livestock, land-use conflicts invariably arise, typified by problems associated with malignant catarrhal fever (MCF) in East Africa and foot-and-mouth disease in southern Africa. MCF has been a major factor contributing to the decline in livestock production in pastoralist communities living in and around protected areas of East Africa, leading to a growing demand for cultivation, a form of land-use generally incompatible with wildlife conservation. In other resource-poor communities, a deteriorating livestock production base, exacerbated by diseases transmitted from wildlife, has also fuelled a growth in illegal wildlife hunting to meet growing demands for both dietary protein and cash income.

Options to control infection in wildlife are limited and current strategies, such as culling and movement restriction, have major negative repercussions on wild populations. The engagement of wildlife managers in issues relating to both public health and livestock development is therefore crucial in order to develop effective and appropriate strategies for disease control.