West Nile Virus in Birds: Modelling Infections in Germany

West Nile virus (WNV) is an arthropod-borne virus that primarily circulates among susceptible birds and mosquitoes of the genus Culex. Humans can become infected as well, leading to severe illness and even death in rare cases. Germany recorded the first autochthonous emergence of WNV in animals in 2018. Since then, human and animal infections have increased in number and expanded spatially beyond persistent hotspots in Eastern Germany and Berlin, making WNV a growing public health concern. Spatial modelling of infections is instrumental in assessing risk and predicting disease occurrence. Previous research has shown that climate, diverse types of land cover and parameters related to vector activity play substantial roles in WNV transmission dynamics. This study assesses which biotic and abiotic drivers best explain WNV infections in birds in Germany in the year 2019, using spatial regression. The model identified five susceptible bird species, vectorial capacity of the mosquito Culex pipiens, natural vegetation cover and interactive effects as key predictors. These results demonstrate that host-vector interactive dynamics, driven by temperature and supported by natural vegetation, explain avian WNV infections better than other land cover and climatic variables. This novel finding highlights the pivotal role of highly susceptible bird species in the emergence of WNV and informs future modelling of infection occurrences.

Keywords: West Nile virus, vector-borne diseases, spatial regression model, host-vector interactions, West Nile virus disease