Key Points

Chikungunya, Dengue, and Zika

Indigenous cases

As of July 29, 2025, 19 outbreaks of local transmission have been identified in mainland France:

• 14 chikungunya outbreaks (1 to 13 cases per outbreak)

• 5 dengue outbreaks (1 to 2 cases per outbreak)

These total 55 cases and 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 and Nouvelle-Aquitaine.

The number of transmission clusters highlights the significant risk of local transmission of these viruses in mainland France. Additional cases are likely to be identified, including outside the usual transmission zones.

Santé publique France reiterates the importance of reporting cases, which enables rapid intervention to limit transmission, as well as the importance of protective measures against mosquito bites and efforts to control larval breeding sites.

Imported cases

From May 1, the start of enhanced surveillance, through July 29, 2025, the following were identified:

• 867 imported cases of chikungunya

• 659 imported cases of dengue

• 3 imported cases of Zika

West Nile virus infections

Autochthonous cases

The first locally acquired case of West Nile virus in 2025 was identified in mainland France. The case is located in the Provence-Alpes-Côte d'Azur region and first presented symptoms on July 15.