An Investigation of Infectious Disease Dynamics in African Carnivores: Identifying Reservoirs and Risk Factors and Investigating Control Strategies

Infectious disease (pathogens) can cause major wildlife population declines and may pose an important conservation threat. African wild dogs ( Lycaon pictus) are one of the world's most endangered carnivores and pathogens may impede their long-term persistence. Here, I investigated pathogen dynamics in African carnivores, including wild dogs, and examined the conservation benefits of wild dog vaccination. First, I examined wild dogs across Africa for evidence of exposure to rabies virus, canine distemper virus (CDV), canine parvovirus, canine coronavirus, and Babesia spp. Most pathogens were widespread in wild dog populations, however Babesia was never detected. Patterns of exposure suggested: rabies virus and coronavirus exposure may be positively associated with domestic dog (Canis familiaris) contact; contact with wild carnivores as well as domestic dogs may be important in determining CDV exposure; and parvovirus may persist in wild dog populations in the absence of domestic dog contact. Second, I investigated serological patterns of CDV and rabies virus exposure in Kenyan domestic dogs, wild dogs, black-backed jackals ( Canis mesomelas), spotted hyenas (Crocuta crocuta), striped hyenas (Hyaena hyaena) and lions (Panthera leo). Patterns of exposure suggested that domestic dog, but not wild carnivore, populations were capable of maintaining rabies virus and may therefore be a reservoir. No carnivore population in the study area appeared to have maintained CDV, which suggests an external or cryptic reservoir or metareservoir. Finally, I developed a mathematical model to evaluate the conservation impact of various wild dog vaccination strategies. Simulations indicated that the most effective vaccination strategy depended on the vaccinated dog's age and social status, the number of vaccinated wild dogs per pack and packs per population, and the risk of pathogen exposure a pack experienced. The optimal strategy was additionally influenced by population level factors, such as Allee effects and the rate of recovery and immunity induced by a pathogen. Initial steps towards understanding pathogen risk to wild dogs have been taken and possible solutions to protect wild dogs and potentially other endangered carnivores have been assessed; however continued monitoring and careful deliberations are needed to identify situations in which intervention is necessary to mitigate pathogen risks.