Climate change contributes to rise of West Nile virus in Europe

West Nile virus is transmitted by birds and mosquitoes, with mammals – primarily humans and horses – acting as dead-end hosts who cannot retransmit the virus to mosquitoes. Although infection in humans is often asymptomatic, about 25% of victims develop symptoms such as fever and headache, and less than 1% develop more serious neurological complications that can be fatal. Climate change has previously been cited as a possible cause for the rise of the virus in Europe, but until now there has been no formal establishment of the connection.

“Our results point to the major role of climate change in the rise of West Nile virus in the southeast of Europe,” says Diana Erazo, lead author of the study and a postdoctoral researcher at the Spatial Epidemiology Lab. “Our results also show a recent and dramatic increase in the number of people at risk of exposure. That is partly because of an increase in population density, but climate change remains a crucial factor that influences the risk of exposure.”

“This is the face of climate change,” says Professor Wim Thiery, climate scientist at VUB and co-author of the study. “Alongside escalating climate extremes, the emergence of tropical diseases in Europe is unfortunately one of the many logical consequences of our addiction to oil, coal and gas.”

The investigation was made possible thanks to the collaboration of researchers with varying expertise and is the result of an interdisciplinary approach.

“Our work illustrates how climate data can be used effectively in an epidemiological context,” says Simon Dellicour, coordinator of the study and head of the Spatial Epidemiology Lab. “Climate change poses an increasing public health challenge. To adopt correct surveillance and intervention strategies, we need to further investigate the evolution of infectious disease spread under different scenarios of future climate change.”

Estimated evolution in the risk of local circulation of West Nile virus across Europe since the beginning of the last century. The successive maps show (a) the estimated evolution of ecological suitability based on current environmental data and (b) a hypothetical scenario representing a world without climate change. © Erazo et al.

Reference: Erazo D, Grant L, Ghisbain G, Marini G, Colón-González FJ, Wint W, Rizzoli A, Van Bortel W, Vogels CBF, Grubaugh ND, Mengel M, Frieler K, Thiery W, Dellicour S (2024). Contribution of climate change to the spatial expansion of West Nile virus in Europe. Nature Communications 15: 1196 https://doi.org/10.1038/s41467-024-45290-3