Relationship between burden of infection in ungulate populations and wildlife/livestock interfaces

Abstract

In southern African transfrontier conservation areas (TFCAs), people, livestock and wildlife share space and resources in semi-arid landscapes. One consequence of the coexistence of wild and domestic herbivores is the risk of pathogen transmission. This risk threatens local livelihoods relying on animal production, public health in the case of zoonoses, national economies in the context of transboundary animal diseases, and the success of integrated conservation and development initiatives. The level of interaction between sympatric wild and domestic hosts, defining different wildlife/livestock interfaces, characterizes opportunities of pathogen transmission between host populations. Exploring the relationship between infection burden and different types of wildlife/domestic interfaces is therefore necessary to manage the sanitary risk in animal populations through control options adapted to these multi-host systems. Here, we assessed the infection burdens of sympatric domestic cattle (Bos taurus/Bos indicus) and African buffalo (Syncerus caffer) at an unfenced interface and compared the infection burdens of cattle populations at different wildlife/livestock interfaces in the Great Limpopo TFCA. Patterns of infection in ungulate populations varied between wild and domestic hosts and between cattle populations at different wildlife/livestock interfaces. Foot-and-mouth disease, Rift Valley fever and theileriosis infections were detected in buffalo and cattle at unfenced interfaces; bovine tuberculosis was only present in buffalo; and brucellosis and lumpy skin disease only in cattle. At unfenced interfaces, cattle populations presented significantly higher Theileria parva and brucellosis prevalence. We hypothesize that cattle populations at wildlife/livestock interfaces face an increased risk of infection compared to those isolated from wildlife, and that the type of interface could influence the diversity and quantity of pathogens shared. Additional host behavioural and molecular epidemiological studies need to be conducted to support this hypothesis. If it is confirmed, the management of wildlife/livestock interfaces will need to be considered through the prism of livestock and public health.

Fig. 1.

Study sites and different wildlife/livestock interfaces. The map (top left) presents the south-eastern part of southern Africa encompassing Mozambique, South Africa and Zimbabwe. The Great Limpopo Transfrontier Conservation Area (GLTFCA) is represented by an ellipse and a square indicates the zoom for the rest of the Figure. On the main map, the grey area represents protected areas, N.P. indicates National Parks, Malilangwe is a conservancy and Malipati S.A. refers to the Malipati Safari Area, a hunting concession. The single line represents international borders. Each village representing a sampling unit in the study is indicated by a black dot and the circle linked to this dot refers to the type of wildlife/livestock interface: light grey represents livestock and dark grey represents wildlife; the double vertical line separating the circle indicates a fenced interface and a difference in level of shading represents an interface with no fence.