Key Points

Chikungunya, dengue, Zika

• Seven episodes of local transmission detected:

  • Six episodes of local transmission of chikungunya identified in the region as of September 23, 2025, accounting for 46 cases: Drôme (Montoison and Suze-la-Rousse), Isère (Claix, Eybens, and Varces), and Savoie (St Ours). An outbreak is particularly active in Eybens (38) with 35 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 September 23, 2025: 159 imported cases of chikungunya, 147 imported cases of dengue, and two imported cases of Zika;

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

West Nile

• From May 1 to September 23, 2025, one human case of West Nile virus infection, likely acquired through a vector, was identified in Puy-de-Dôme.