Spatiotemporal Evolution of West Nile Virus Transmission Risk in Europe under Climate Change: A Dual-Methodological Approach

As West Nile virus (WNV) transmission dynamics in Europe are increasingly reshaped by climatic forcing, understanding the spatiotemporal evolution of infection risk is paramount for public health preparedness. This study employs a dual-methodological framework to assess WNV transmission potential under historical (2010–2024) and future (2061–2090) climate scenarios (SSP2-4.5 and SSP5-8.5). We apply two distinct approaches: empirical statistical evidence derived from Distributed Lag Non-linear Models (DLNM) and mechanistic insights from the bioclimatic suitability metric, Index-P.

Our analysis reveals a pronounced latitudinal shift in WNV infection risk, characterized by significant westward expansion and intensification across Western and Central-Eastern Europe. This trend signifies that temperate regions, previously considered marginal for WNV, are now transitioning into high-risk zones due to increasingly favorable bioclimatic conditions. Conversely, Southern Europe transitions toward a state of 'thermal saturation, while it remains a primary endemic focus, the risk levels are stabilizing as environmental conditions approach the upper threshold of the virus's optimal ecological niche.

Beyond geographical broadening, the analysis identifies a critical temporal elongation of the transmission season. By the late century, the risk window in Western and Central Europe is projected to expand to five or six months, effectively converging with the seasonal profiles currently observed in Mediterranean latitudes. This shift transforms WNV from a transient summer threat into a prolonged annual challenge, with climatic suitability favoring viral circulation for approximately half the year across much of the continent.

The convergence of statistical and mechanistic evidence identifies climate change as the pivotal catalyst for the homogenization of WNV infection risk in Europe. By identifying specific lagged effects, the DLNM component provides empirical lead times for outbreaks, while the Index-P framework offers a process-based understanding of shifting ecological niches. These complementary findings underscore an urgent need for climate-informed early-warning systems and adaptive, region-specific vector control strategies to mitigate the virus's expanding reach.