In June, the Institut Pasteur confirmed an unprecedented situation this summer, with locally acquired, mosquito-transmitted disease accelerating in France.
As of August 26, 2025, Public Health France reported 37 episodes of indigenous vector transmission have been identified in mainland France:
There have been 30 episodes of chikungunya, resulting in a total of 228 cases.
And seven separate episodes of dengue fever, totaling 15 cases.
They are located in the Provence-Alpes-Côte d’Azur, Corsica, Occitanie, Auvergne-Rhône-Alpes regions, already affected in previous years, and for the first time in Grand Est, Nouvelle-Aquitaine, and Bourgogne-Franche-Comté.
Furthermore, 15 human cases of vector-borne West Nile virus infection have been identified in five departments of mainland France. The affected regions are PACA, Occitanie, and, for the first time, Île-de-France.
Additionally, travel-related cases continue to be confirmed in 2025.
France has reported 946 imported cases of chikungunya, 825 imported cases of dengue fever, and seven imported cases of Zika.
When visiting France this year, the U.S. CDC offers various travel vaccine recommendations for anyone visiting disease outbreak areas. Currently, there are no vaccines available for West Nile or Zika viruses.
However, chikungunya vaccination services are offered in both France and the USA.