West Nile Virus in Birds: Modelling Infections in Germany integrating Susceptible Bird Species, Vectorial Capacity, Land Cover and Climatic Predictors

Germany recorded the first autochthonous emergence of West Nile Virus (WNV) in animals in 2018. Since then, human and animal infections have increased in numbers and spatially spread beyond their persistent infection hotspots in Eastern Germany and Berlin. By spatially modelling WNV bird infection occurrences in Germany in 2019, this study assesses which biotic and abiotic drivers best predict WNV infections in birds. Predictors include the occurrence of six bird species that are highly susceptible to WNV infection in Germany, based on seroprevalence of WNV ribonucleic acid, air temperature-derived vectorial capacity of the primary vector mosquito Culex pipiens, as well as landcover and climatic variables. The spatial model of 2019 bird infections identified five susceptible bird species, Culex pipiens vectorial capacity, the Normalized Differential Vegetation Index (NDVI) and their interactions as key predictors. Results indicate that interactive host-vector dynamics, driven by mean air temperature and supported by natural vegetation, explain WNV infections in birds more strongly than other landcover or climatic variables. This research highlights the pivotal role of highly susceptible bird species in WNV emergence and spatial spread and informs future modelling of WNV expansion into new regions.