Key Points

Chikungunya, Dengue, and Zika

Indigenous cases

As of September 8, 2025, 49 episodes of indigenous vector-borne transmission have been identified in mainland France:

• 38 chikungunya outbreaks totaling 382 cases (1 to 71 cases per outbreak; 10 of these outbreaks are closed);

• 11 dengue outbreaks totaling 21 cases (1 to 5 cases per outbreak; 5 of these outbreaks are closed).

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

Imported cases

• 966 imported cases of chikungunya

• 894 imported cases of dengue

• 7 imported cases of Zika

West Nile virus infections

Indigenous cases

As of September 8, 2025, 23 human cases of vector-borne West Nile virus infection have been identified in 7 departments of mainland France.

The affected regions are Provence-Alpes-Côte d'Azur, Occitanie, and, for the first time, Île-de-France and Auvergne-Rhône-Alpes.