Rabies is a viral disease which poses a substantial threat to both public health and wildlife conservation. This thesis explores an aspect of rabies epidemiology which is still little understood: non-lethal rabies exposure. The evidence for, and implications of, non-lethal rabies exposure are explored both in domestic dogs (the primary rabies reservoir in Africa and Asia) and endangered African wild dogs (to which rabies poses a substantial threat to population persistence).
Through a combination of literature review and serological sampling of domestic dogs, I show that high seroprevalences of rabies-specific antibodies have been detected in unvaccinated domestic dog populations, which could be explained by non-lethal exposure leading to generation of an immune response. However, interpretation of serology is complicated by variation between test methods, and some serological results are likely to represent false positives. Modelling showed that naturally acquired immunity could contribute to the observed dynamics of low-level endemic rabies in domestic dog populations, however also highlighted the importance of other factors such as spatial structure. Extending this model showed that naturally acquired immunity is unlikely to influence the vaccination coverage required for rabies control and indicated substantial challenges to using serology to conduct rabies surveillance.
Collation of reports of rabies outbreaks in wild dog populations highlighted the high mortality resulting in unvaccinated individuals, with limited evidence for non-lethal exposure. Based on parameter estimates obtained from these reports, modelling of rabies in a wild dog population suggested naturally acquired immunity is unlikely to substantially influence rabies dynamics in this species. Evidence from both outbreak reports and modelling emphasised the importance of continuing vaccination in domestic dogs to reduce spillover of rabies into the wild dog population. However, where rabies remains endemic in domestic dogs, results indicated that direct vaccination of wild dogs can provide partial protection, and proactive management of outbreaks could improve outcomes for this endangered species.