West Nile virus cases rise in France

Health authorities in France are monitoring an increase in West Nile virus cases. As of August 30, 2026, Santé publique France reported 39 autochthonous cases—infections contracted within mainland France—across the Provence-Alpes-Côte d’Azur, Occitanie, Île-de-France, and Auvergne-Rhône-Alpes regions.

While many infections are asymptomatic, a small proportion of patients may experience serious neurological complications requiring hospitalization. Unlike dengue or chikungunya, which are primarily spread by tiger mosquitoes, West Nile virus is mainly transmitted by common mosquitoes of the Culex genus. The virus cycle typically begins in birds.

To mitigate risks, health agencies such as Anses recommend several preventative measures to reduce mosquito populations. Key actions include eliminating standing water in containers like flowerpot saucers, buckets, or gutters to prevent larval development, hermetically sealing rainwater collection tanks with fine mesh, and installing mosquito nets on windows to prevent adult insects from entering homes.