The impacts of host community composition, clustering and vector host choice on zoonotic mosquito-borne virus...

Zoonotic mosquito-borne viruses, including West Nile, Rift Valley fever and Japanese encephalitis viruses, present a substantial public health burden in some countries, with transmission involving complex interactions between multiple vector and host species, making control difficult. While host community composition is known to affect transmission, the role of host community structure coupled with mosquito aggregation behaviour remains poorly understood. Motivated by furthering understanding of potential Japanese encephalitis virus transmission routes and persistence in contexts where cattle - dead-end hosts - are dominant in the community, we developed a patch model in which host distributions and the resulting mosquito biting allocation among patches are fixed within each simulation. This framework represents mosquito host-seeking across two scales: long-range aggregation toward host-dense patches and short-range host species choice determined by local host availability and innate vector preference. Using this model, assuming that vectors prefer dead-end hosts (choosing them 90% of the time if given an equal choice of other hosts), we explored the potential effect of host clustering, patch fragmentation, and the strength of mosquito aggregation on the basic reproduction number. Our results show that identical host communities can yield very different transmission outcomes depending on how they are distributed and the level of mosquito aggregation. Under circumstances where dead-end hosts are preferred by vectors, if competent hosts are clustered and mosquitoes aggregate strongly, transmission may be amplified compared with uniformly distributed hosts and vectors. If dead-end hosts are clustered, transmission may be diluted as mosquitoes aggregate in patches where dead-end hosts are dominant in the host community. Fragmentation effects are context-dependent: when competent hosts are clustered and mosquitoes aggregate, increasing patches increases transmission. When dead-end hosts are clustered, transmission decreases under strong mosquito aggregation with increasing number of patches. These findings highlight that variations in the local spatial context of host-vector interactions can lead to variations in disease risk. Locally-informed surveillance and targeted interventions may therefore be important in attempts to prevent outbreaks of zoonotic mosquito-borne viruses.