Key Points

Chikungunya, Dengue, and Zika

Indigenous cases

As of August 12, 2025, 29 outbreaks of local transmission have been identified in mainland France:

• 23 chikungunya outbreaks totaling 115 cases (1 to 23 cases per outbreak); 6 of these outbreaks have been closed

• 6 dengue outbreaks totaling 11 cases (1 to 4 cases per outbreak), 1 of which has been resolved

They are located in the Provence-Alpes-Côte d'Azur, Corsica, Occitanie, and Auvergne-Rhône-Alpes regions, which were already affected in previous years, and for the first time in Grand Est, Nouvelle-Aquitaine, and Bourgogne-Franche-Comté. The high number of transmission clusters illustrates the significant risk of local transmission of these viruses in mainland France. Additional cases are likely to be identified, including outside the usual transmission zones.

Santé publique France reiterates the importance of reporting cases, which enables rapid intervention to limit transmission, as well as the importance of protective measures against mosquito bites and the control of larval breeding sites.

Imported cases

From May 1, the start of enhanced surveillance, through August 12, 2025, the following were identified:

• 914 imported cases of chikungunya

• 746 imported cases of dengue

• 4 imported cases of Zika

West Nile virus infections

Indigenous cases

As of August 12, 2025, three outbreaks of local transmission have been identified in mainland France:

• 2 outbreaks in Provence-Alpes-Côte d'Azur totaling 5 cases

• 1 outbreak in Île-de-France, totaling 2 cases