The ARS Auvergne-Rhône-Alpes states that most dengue cases reported in mainland France involve international travelers who were infected with the mosquito-transmitted virus while visiting a tropical region.
If people return to France infected, dengue symptoms occur on average within 4 to 7 days after the infective bite. These are considered imported cases.
However, recent reports suggest that a local outbreak may occur in July 2025.
Approximately 50 kilometers southwest of Lyon, France, Saint-Chamond, in the Auvergne-Rhône-Alpes region, has confirmed a second locally acquired case of Dengue as of July 15, 2025.
‘At this stage, it is not possible to establish a link with the first indigenous case identified in Saint-Chamond, as the investigations are still ongoing,’ wrote ARS Auvergne-Rhône-Alpes.
An entomological survey conducted on July 18, 2025, confirmed the presence of tiger mosquitoes in areas frequented by the infected person and informed residents of an adulticide treatment. These mosquitoes carry dengue viruses.
Around one hundred homes in the affected area have been informed.
In 2024, France reported 82 locally transmitted cases of dengue fever. Outbreaks were identified in the Provence-Alpes-Côte d’Azur, Occitanie, and Auvergne-Rhône-Alpes regions.
The World Health Organization has classified Dengue as a grade 3 emergency, with an estimated 4 billion people at risk in approximately 110 countries, including areas within the United States, such as Florida and Puerto Rico.
While numerous countries offer Dengue vaccinations, only Puerto Rico continues to provide a first-generation vaccine to children.