Are all hosts created equal? Transmission dynamics in a natural multi-host parasite community

点击翻译按钮获取中文摘要

Many of the most pressing concerns about emerging infectious disease in humans (eg pandemic influenza, West Nile virus, Hantavirus) and wildlife (eg bovine TB in cattle and badgers, squirrel pox transmission from grey to red squirrels) arise from parasites moving from one host species to another. As such there is considerable interest in how the composition of possible hosts in a community affects whether a disease spreads or not. Each host species can differ in their susceptibility to the parasite, their social structure and/or behaviour, so that the composition of the host community plays a key role in determining why some parasites cause an epidemic (i.e HIV), while others don't (i.e. Ebola). To aid our understanding of these complex, real-world communities, several mathematical models have been developed which show that the contribution each host species makes to the parasite's ability to spread is fundamental in determining whether the disease persists, and the outcome of targeted control. To date, however, these theories have not been tested with actual data, meaning they largely remain abstract conceptual frameworks. In particular, it is not known whether the host species' contributions to disease spread can be determined solely from the number of infected individuals within each host species. This is important as most studies of parasites that infect multiple hosts are likely to be purely observational, because it is logistically or ethically unfeasible to conduct the necessary experiments. However, there may be general guidelines, based on fundamental aspects of host-parasite ecology that can be used to infer these host contributions to parasite transmission and persistence. For example, both the transmission biology of the parasite (ie how it moves from one host to another) and the way host species interact in the community (eg their movement patterns, habitat usage, resource competition etc) will determine how each host species contributes to parasite persistence. Clearly, there is a need to determine whether disease patterns that we see in nature, combined with a basic understanding of host-parasite biology, can be used to predict how parasites will respond to control efforts targeting one host species or another. We will use a highly novel combination of large-scale manipulation experiments and mathematical modelling to measure host species contributions to parasite transmission across a diverse, natural multi-host-multi-parasite community. Overall we will provide one of the most comprehensive views of how very different parasites, with different transmission modes, use multiple host species to persist, and the implications for how such parasites respond to targeted host treatment. Given the increasing concerns about emerging infectious diseases around the globe, it has never been more pressing to develop a genuine understanding of the factors affecting parasite invasion, transmission, persistence, and control. This project will be a major step in that direction.