Mosquito Aggregation and Host Clustering Reshape Zoonotic Virus Transmission Risk

Zoonotic mosquito-borne viruses such as West Nile, Rift Valley fever and Japanese encephalitis impose a substantial public health burden in parts of the world, and their transmission depends on intricate interactions among multiple vector and host species. A new modelling study by Jennifer S. Lord, Michael B. Bonsall and Tijani A. Sulaimon examines a poorly understood piece of this puzzle: how the spatial structure of host communities, combined with the way mosquitoes aggregate their bites, shapes the potential for viral transmission.

The researchers built a patch model in which host distributions and the resulting allocation of mosquito biting across patches are fixed within each simulation. Mosquito host-seeking is represented at two scales. At long range, vectors aggregate toward patches where hosts are dense; at short range, they choose among host species according to local availability and an innate preference. This allowed the team to explore how host clustering, patch fragmentation and the strength of mosquito aggregation influence the basic reproduction number, a key measure of transmission potential.

A central scenario focused on Japanese encephalitis virus in settings where cattle dominate the host community. Cattle are dead-end hosts for the virus, meaning they can be bitten but do not pass the infection on to other mosquitoes. The model assumed vectors prefer dead-end hosts, selecting them 90 percent of the time when given an equal choice of other hosts, a configuration that makes the spatial arrangement of competent versus dead-end species especially consequential.

The results show that identical host communities can produce very different transmission outcomes depending solely on how hosts are distributed and how strongly mosquitoes aggregate. When competent hosts are clustered and mosquitoes aggregate strongly, transmission may be amplified relative to a landscape with uniformly distributed hosts and vectors, because concentrated biting on infectious hosts accelerates the cycle of infection.

The pattern reverses when dead-end hosts are clustered. In that case, transmission may be diluted, as mosquitoes concentrate their bites in patches dominated by hosts that cannot sustain the virus, effectively diverting vectors away from competent amplifying hosts.

Fragmentation effects proved context-dependent. When competent hosts are clustered and mosquitoes aggregate, increasing the number of patches raises transmission. When dead-end hosts are clustered, transmission decreases with increasing patch number under strong mosquito aggregation. The same landscape change can therefore push risk in opposite directions depending on which species occupy the clusters.

The authors emphasize that these are model-based findings about potential transmission dynamics rather than measurements from field outbreaks. The framework fixes host distributions and biting allocation within each simulation, and its conclusions rest on the assumed strength of vector preference for dead-end hosts, so the results describe possible outcomes under the modelled conditions.

Nevertheless, the study carries a practical message: the local spatial context of host-vector interactions can generate substantial variation in disease risk even within the same community composition. Locally informed surveillance and targeted interventions may therefore be important in attempts to prevent outbreaks of zoonotic mosquito-borne viruses, particularly in regions where dead-end hosts such as cattle are abundant and Japanese encephalitis transmission is a concern.

Subject of Research: Modelling the effects of host community composition, clustering and vector host choice on zoonotic mosquito-borne virus transmission

Article Title: The impacts of host community composition, clustering and vector host choice on zoonotic mosquito-borne virus transmission

Article References: Lord, J. S., Bonsall, M. B., & Sulaimon, T. A. (2026). The impacts of host community composition, clustering and vector host choice on zoonotic mosquito-borne virus transmission. PLOS Neglected Tropical Diseases, 20(10), e0014758. https://doi.org/10.1371/journal.pntd.0014758

Image Credits: AI Generated

DOI: 10.1371/journal.pntd.0014758

Keywords: Japanese encephalitis virus, West Nile virus, Rift Valley fever, mosquito vectors, host community composition, dead-end hosts, patch model, basic reproduction number, transmission dilution, spatial heterogeneity, zoonotic disease, impacts