Key Points

Chikungunya, Dengue, and Zika

Indigenous Cases

• As of September 14, 2026, 17 outbreaks (+2 compared to the previous week) of indigenous vector-borne transmission were identified in mainland France:
  • 13 chikungunya outbreaks (+2 compared to the previous week), totaling 75 cases (1 to 30 cases per outbreak) in the Tarn and Lot departments (Occitanie), in Gironde, in the Landes (Nouvelle-Aquitaine), and in Val-de-Marne (Île-de-France);
  • 4 dengue outbreaks (no new outbreaks compared to the previous week) totaling 6 cases (1 to 2 cases per outbreak) in the Tarn and 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 13, 2026, the following cases were identified:

• 143 imported cases of chikungunya
• 403 imported cases of dengue
• 15 imported cases of Zika

West Nile virus infections

Locally transmitted cases

• As of September 14, 2026, 92 locally acquired cases of West Nile virus infection (+36 compared to the previous week) have been identified in mainland France. These cases are located in the Provence-Alpes-Côte d'Azur region (3 departments), Occitanie region (5 departments), Île-de-France region (6 departments), Auvergne-Rhône-Alpes (Drôme department), Nouvelle-Aquitaine (Gironde department), Pays de la Loire (2 departments), and Centre-Val de Loire (Loiret department). For 8 cases, no specific location of exposure could be identified.
• For the first time, human cases of West Nile virus infection have been detected in the departments of Aude (Occitanie), Seine-et-Marne (Île-de-France), Drôme (Auvergne-Rhône-Alpes), Loire-Atlantique, Maine-et-Loire (Pays de la Loire), and Loiret (Centre-Val de Loire).