Key Points

Chikungunya, Dengue, and Zika

Indigenous cases

As of September 28, 2026, 23 outbreaks (+6 new outbreaks compared to the previous week) of locally transmitted vector-borne disease were identified in mainland France:

• 19 chikungunya outbreaks (+6 new outbreaks compared to the previous week), totaling 125 cases (1 to 30 cases per outbreak) in the Tarn, the Lot, the Gard (Occitanie), in Gironde, in the Landes (Nouvelle-Aquitaine), in Val-de-Marne (Île-de-France), and in the Var (Provence-Alpes-Côte d'Azur);
• 4 dengue outbreaks (no new outbreaks compared to the previous week) totaling 6 cases (1 to 2 cases per outbreak) in the Tarn, 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 27, 2026, the following were identified:

• 152 imported cases of chikungunya
• 424 imported cases of dengue
• 17 imported cases of Zika

West Nile virus infections

Locally acquired cases

• As of September 28, 2026, 145 locally acquired cases of West Nile virus infection (+28 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 affected), Occitanie (7 departments affected), Île-de-France (7 departments affected), Auvergne-Rhône-Alpes (3 departments affected), Nouvelle-Aquitaine (Gironde department), Pays de la Loire (3 departments affected), and Centre-Val de Loire (Loiret department). For 14 cases, no specific site of infection could be identified.