Key Points

Chikungunya, Dengue, and Zika

Indigenous Cases

As of September 6, 2026, 15 outbreaks (+3 compared to the previous week) of locally transmitted vector-borne disease were identified in mainland France:

• 11 outbreaks (+3 compared to the previous week) of chikungunya totaling 57 cases (1 to 28 cases per outbreak) in the Tarn and the Lot (Occitanie), in Gironde (Nouvelle-Aquitaine), and in Val-de-Marne (Île-de-France);
• 4 outbreaks (+0 compared to the previous week) of dengue, totaling 6 cases (1 to 2 cases per outbreak) in the Tarn, the Hérault (Occitanie), the Dordogne (Nouvelle-Aquitaine), and the Bouches-du-Rhône (Provence-Alpes-Côte d'Azur).

Investigations and prevention and control measures are underway for the various outbreaks that are still active.

Imported cases

From May 1, when enhanced surveillance began, through September 6, 2026, the following were identified:

• 136 imported cases of chikungunya
• 389 imported cases of dengue
• 13 imported cases of Zika

West Nile virus infections

Locally acquired cases

• As of September 6, 2026, 56 locally acquired cases (+17 compared to the previous week) of West Nile virus infection had been identified in mainland France. They are located in the Provence-Alpes-Côte d'Azur region (in 3 departments), Occitanie (4 departments), Île-de-France (5 departments), Auvergne-Rhône-Alpes (Drôme department), and Nouvelle-Aquitaine (Gironde department). For 6 cases, no specific site of infection could be identified.
• This is the first time that human cases of West Nile virus infection have been detected in the departments of Aude (Occitanie), Seine-et-Marne (Île-de-France), and Drôme (Auvergne-Rhône-Alpes).