Key Points

Chikungunya, Dengue, and Zika

Indigenous cases

As of August 26, 2025, 37 episodes of local vector-borne transmission have been identified in mainland France:

• 30 chikungunya outbreaks totaling 228 cases (1 to 36 cases per outbreak), 7 of which have been closed;

• 7 dengue outbreaks totaling 15 cases (1 to 5 cases per outbreak), 4 of which have been resolved.

These outbreaks are located in the Provence-Alpes-Côte d'Azur, Corsica, Occitanie, and Auvergne-Rhône-Alpes regions, which were already affected in previous years, and for the first time in Grand Est, Nouvelle-Aquitaine, and Bourgogne-Franche-Comté.

Imported cases

• 946 imported cases of chikungunya

• 825 imported cases of dengue

• 7 imported cases of Zika

West Nile virus infections

Indigenous cases

As of August 26, 2025, 15 human cases of vector-borne West Nile virus infection have been identified in 5 departments of mainland France. The affected regions are Provence-Alpes-Côte d'Azur (PACA), Occitanie, and, for the first time, Île-de-France.