Distribution of West Nile virus cases reported in the European Center for Disease Prevention and Control database until 2019

The density of both “probable” and “confirmed” cases is shown for each administrative area for which there was at least one confirmed case before 2020. Specifically, the number of West Nile virus (WNV) cases by aggregating both “probable” and “confirmed” per km² (a) or per 100,000 people (b), either considering the NUTS3 or optimized NUTS3 administrative polygons. Nomenclature of Territorial Units for Statistics or NUTS (French: Nomenclature des unités territoriales statistiques) is a geocode standard for referencing the administrative divisions of countries for statistical purposes. The NUTS numbering refers to the size of the administrative units, with NUTS1 the most aggregated and NUTS3 the smallest, with population size of 150,000 to 800,000. Darker grey areas correspond to Switzerland and Bosnia and Herzegovina, countries that are not included in the ECDC WNV surveillance. The administrative areas of those countries were not considered when training ecological niche models. The United Kingdom is also not included in the ECDC WNV surveillance but was considered when training the models as the country has not reported any WNV cases. (Source: Erazo D, Grant L, Ghisbain G, et al. Contribution of climate change to the spatial expansion of West Nile virus in Europe. Nat Commun 2024;15[1]:1196. Creative Commons Attribution 4.0 International [CC BY 4.0] license, creativecommons.org/licenses/by/4.0.)