Key Points 

Chikungunya, dengue, Zika

• Enhanced surveillance from May to November aimed at early case detection and reducing the risk of transmission within the region; epidemiological investigation of each case to identify areas where the viruses are circulating and guide vector control measures.
• A very high number of reports received by the ARS Paca in 2025; over 900 reports processed, the majority between August and September.
• Significant import pressure linked to French overseas territories; over 100 imported cases of chikungunya, the majority of which were travelers returning from Réunion, and over 120 imported cases of dengue, mainly from travelers returning from the French Antilles.
• Very active viral circulation in Provence-Alpes-Côte d'Azur (PACA), the region most affected in mainland France; more than 450 locally acquired cases of chikungunya identified, as well as 16 locally acquired cases of dengue.

West Nile virus infections

• Enhanced surveillance from May to November aimed at the early detection of viral circulation in the country; securing products derived from the human body.
• Active viral circulation in Provence-Alpes-Côte d'Azur (PACA), the region most affected in France; 30 locally acquired cases of West Nile virus infection, mainly in the Bouches-du-Rhône and Var departments.