Quantifying the invasion risk of West Nile virus: insights from a multi-vector/multi host SEIR model

Abstract

Abstract The invasion of vector-borne diseases depends on the type of specific features of the vector and hosts at play. Within the Culex pipiens complex, differences in ecology, biology, and vector competence can influence the risk of West Nile virus (WNV) outbreaks. To determine which life-history traits are most important, we constructed an epidemiological Susceptible-Exposed-Infectious-Recovered model with three vector eco-types, Culex pipiens pipiens, Cx. pip. molestus, and their hybrids, and two vertebrate hosts, birds (as amplifying hosts) and humans (as dead-end hosts). We investigated how differences in feeding preferences and transmission rates influenced WNV transmission across different habitats and two simulated scenarios, i.e., global change and increasing urbanisation settings, to investigate the impact of increasing mosquito and human abundance on the WNV transmission risk. Our results showed that vector feeding preferences and the transmission rate between mosquitoes and birds were the parameters that most impacted WNV invasion risk. Natural habitats were overall more susceptible to WNV invasion, although rural habitats were also susceptible in a climate change scenario. Pipiens-type-related factors dominated virus amplification in natural and rural habitats, while molestus-type-related factors drove the spread of WNV in urban environments. Contrary to common opinion, our findings suggest that hybrids may play only a minor role in WNV transmission. Our study will improve current vector surveillance and control programs by targeting specific vector types in specific environments, especially in rural settings, which are most responsive to environmental shifts. This approach can help reduce wasted time and economic costs while maximizing the efficiency of local public health authorities.