Key Points

Chikungunya, dengue, Zika

• Seven episodes of local transmission detected:

  • Five outbreaks of local transmission of chikungunya identified in the region as of September 9, 2025, accounting for 39 cases: Drôme (Montoison and Suze-la-Rousse), Isère (Claix and Eybens), and Savoie (St Ours). An outbreak is particularly active in Eybens (38), with 29 reported cases and others under investigation.

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

• Summary of imported cases:

  • From May 1 to September 9, 2025: 157 imported cases of chikungunya, 147 imported cases of dengue, and one imported case of Zika.

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

West Nile

• From May 1 to September 9, 2025, one human case of West Nile virus infection, likely acquired through a vector, was identified in Puy-de-Dôme.