Epidemiology of canine rabies at the wildlife interface in the South African Lowveld: A risk assessment of spillover and persistence in wildlife

Rabies is a zoonotic viral infection that causes neurological symptoms, which inevitably result in a horrifying death. Although rabies is mainly seen in animals, it causes tens of thousands of human deaths per year. Most human cases are reported in Africa and Asia, of which the vast majority is contracted by children. Domestic dogs are the main reservoir and vector for the rabies virus, whereas the contribution of wildlife to the overall burden of human rabies is negligible. Nevertheless, the interaction between domestic dogs and wildlife can result in the introduction of rabies into susceptible populations, wherein the virus can be maintained without additional input from domestic dogs. The potential spillover of rabies poses a threat to wildlife conservation, eco-tourism and public health. The aim of this study was to increase the understanding of canine rabies epidemiology and the associated risk for wildlife populations in the Lowveld of South Africa. To address these aims qualitative data of rabies transmission rates between dogs and wildlife was collected via semi-structured interviews (SSIs) with key informants in the conservation areas. Additionally, existing State Veterinary records on the occurrence of dogs in the reserves, animal rabies cases and dog/wildlife contacts were analyzed. The quantitative data based on the State Veterinary records was collected in the period between 2008 and 2012. Dogs spotted inside the conservation area were killed, after which samples to test for the presence of rabies virus were taken. A number of 233 dogs were shot in the conservation area, 217 of which were sampled for rabies virus. In 2009, 76.8% of the dogs was tested positive for rabies, followed by 67.1%, 34.1% en 47.9% in the subsequent three years. In 2009 and 2010, both the number of dogs shot in the park as well as the percentage of rabid dogs was significantly (P <0.0001) higher than in 2011 and 2012. Furthermore, a total of 96 wildlife species was sampled for rabies virus, whereby one baboon and one small spotted genet tested positive. The outcome of the semi-structured interviews showed that managers and staff of the conversation area considered the presence of dogs in the park a problem, mainly because of the potential danger of disease transmission. The participants of the SSIs stated that the majority of the dogs stay close to the fence (100-500m), while a minority penetrates deeper into the park. This was confirmed by geographical analysis. Some participants of the SSIs stated that they have seen interaction between dogs and wildlife. Sometimes these interactions resulted in injury of either the dogs or wildlife. Considering the high prevalence of rabies virus within the population of sampled dogs, the contact between dogs and wildlife species should be considered a (significant) risk for the introduction of the virus into the wildlife populations. Mass dog vaccination is considered the most successful way to eliminate and control canine rabies. Vaccination coverage of 70% is seen as the threshold for the sufficient to control rabies in domestic dogs. To eliminate canine rabies in areas bordering conservation areas, policy makers should prioritize dog vaccination combined with the involvement of the local communities. Only via multidisciplinary collaboration, with the involvement of the central government, district officials, extension workers and communities the fight against rabies can be overcome