Key Points

Chikungunya, dengue, Zika

8 episodes of local transmission detected

• Six episodes of local transmission of chikungunya identified in the region as of October 21, 2025, accounting for 51 cases: Drôme (Montoison and Suze-la-Rousse), Isère (Claix, Eybens, and Varces), and Savoie (Saint-Ours). The latest active outbreak is in Varces (38) with 4 reported cases.

• Two episodes of local dengue transmission, totaling 4 cases: Loire (Saint-Chamond) and Ain (Belley);

Summary of imported cases

• From May 1 to October 21, 2025: 163 imported cases of chikungunya, 151 imported cases of dengue, and two imported cases of Zika;

• Most of these individuals were returning from a trip to French overseas territories.

West Nile

• As of October 21, 2025, two human cases of West Nile virus infection, likely acquired through a vector, were identified in Puy-de-Dôme and Ardèche.