Canine-mediated rabies is a serious zoonosis responsible for at least 55,000 human deaths every year, primarily in less developed communities in Asia and Africa where domestic dogs are free-roaming. The disease can be effectively controlled through vaccinating at least 45% of the dogs in a population; however the impact of vaccinations on disease incidence may be affected by dynamic demographic and immunological processes. Specifically, the contribution of these processes, and their regulatory factors, to vaccination coverage and rabies transmission has not been comprehensively estimated. To improve rabies control, through field interventions and epidemiological modelling, more information regarding the effect of these processes, and their regulatory factors, on population and disease dynamics and vaccinal responses was needed. This required a multifaceted approach, using techniques from the fields of population ecology, vaccine-immunology, social science and epidemiological modelling. Demographic data were collected from four populations of free-roaming domestic dogs, two in South Africa and two in Indonesia where rabies is endemic. Longitudinal, individual-level data were obtained by direct observation and surveys, and community-level data by participatory methods. Longitudinal, serological data were collected from three cohorts within the populations. Epidemiological models were based on epidemic theory and empirical data from this current study and previous studies. A wide array of data were generated relevant to planning rabies control programmes, however of particular importance was evidence regarding positive and negative the impacts of human factors on population and disease dynamics. Nearly all of the dogs were owned, despite being free-roaming, and were accessible for vaccination through their owners; and population size was regulated through human demand for dogs and a substantial fraction of dogs was acquired from outside the communities. These translocated dogs may contribute to the spread of rabies, necessitating widespread and sustained vaccination programmes. Considerable differences in the handleability of dogs between locations and, thus ease of vaccine delivery, may also be attributable to differences in human-dog interactions. Finally, a critical review of the literature, and evaluation of epidemiological models, suggests that human interference in the transmission processes may reduce the incidence of rabies and vaccination threshold. This study has provided specific evidence that human behaviours are likely to be critically important in relation to the transmission and control of canine-mediated rabies – and is the first to properly identify this. Further detailed studies are required to explore these behaviours and how they vary culturally and geographically. In addition, the results highlight the critical role that demographic processes more generally, as well as immunological decay, play in influencing the long term success of rabies vaccination programmes. Overall, this research has provided valuable support for planning rabies control programmes and for parameterisation of epidemiological models of infectious diseases, including rabies.
|Publisher||University of Cambridge|
|Department||Department of Veterinary Medicine|
|University||University of Cambridge|