Key Points

Chikungunya, Dengue, and Zika

Indigenous cases:

As of October 20, 2025, 91 outbreaks of locally transmitted chikungunya and dengue and a total of 795 cases have been identified in mainland France:

• 749 cases of chikungunya spread across 79 outbreaks (1 to 137 cases per outbreak; 40 of these outbreaks have been resolved);

• 29 cases of dengue spread across 12 outbreaks (1 to 9 cases per outbreak; 10 of these outbreaks have been resolved);

• 17 isolated cases of chikungunya for which the exact place of infection could not be identified.

Imported cases

From May 1, the start of enhanced surveillance, through October 20, 2025, the following were identified:

• 1,016 imported cases of chikungunya

• 996 imported cases of dengue

• 11 imported cases of Zika

West Nile virus infections

Indigenous cases

As of October 20, 2025, 57 human cases of vector-borne West Nile virus infection have been identified in 17 departments of mainland France. These cases are located in the Provence-Alpes-Côte d'Azur, Nouvelle-Aquitaine, and Occitanie regions, which have historically been affected by West Nile virus, and in Île-de-France, Auvergne-Rhône-Alpes, and Normandy, which are affected for the first time.

In the Occitanie region, the departments of Haute-Garonne and Tarn-et-Garonne are affected for the first time, as is the department of Lot-et-Garonne in Nouvelle-Aquitaine.