Following the reporting of the first locally acquired case of chikungunya on August 7, 2025, in the town of Eybens in Isère, investigations conducted by the Auvergne-Rhône-Alpes Regional Health Agency (ARS) and Santé publique France have identified 26 locally acquired cases to date.

In light of this, a public information meeting is being organized by the Eybens town hall on September 8 at 6:30 p.m. This public meeting will take place at the Joséphine Baker community hall in the presence of representatives from the Auvergne-Rhône-Alpes Regional Health Agency (ARS), Santé publique France, and EIRAD. The objective is twofold: to inform residents about the evolution of the local outbreak of chikungunya cases in the town and to remind them of the need to adopt simple and effective measures to limit the presence of the tiger mosquito, the vector of this disease.

What diseases can the tiger mosquito transmit?

Beyond the daily nuisance it causes, the tiger mosquito can transmit viral diseases such as dengue, chikungunya, or Zika through its bites. It becomes a carrier of one of these diseases by biting an infected person returning from a trip to tropical areas where these viruses circulate. After 2 to 3 days, it can transmit the virus by biting another person, and this continues throughout its entire life cycle (about one month).

Symptoms generally appear 3 to 7 days after the infectious bite and are characterized by a sudden onset of high fever and joint pain that can be intense, sometimes accompanied by other symptoms (muscle pain, headaches, rash, etc.).

Since May 1, 2025, in the department of Isère, 67 cases of chikungunya, including 31 locally acquired cases, have been confirmed. A case is considered locally acquired when a person contracts the disease without having traveled to an area where the virus is actively circulating in the two weeks preceding the onset of symptoms. Thirty-two imported cases of dengue and one imported case of Zika have also been recorded since the start of the surveillance period. More information on diseases transmitted by the tiger mosquito and their symptoms is available on the ARS website.

A collaborative action and prevention plan implemented in the municipality

Since August 7, the Auvergne-Rhône-Alpes Regional Health Agency (ARS) and its partners have been working to minimize the spread of the virus.

Four mosquito control operations in neighborhoods frequented by infected individuals were carried out by EIRAD to reduce the risk of transmission to others by eliminating adult mosquitoes, which are vectors of the virus; additional treatments may take place in the coming weeks. Two door-to-door epidemiological investigations were conducted by teams from the ARS and Santé publique France among residents of the neighborhood where the affected individuals live to identify any other potential cases and trace the index case.

The public has also been informed and educated about preventive measures. Investigations are currently ongoing to identify any new cases. Depending on the progress of the investigation, other potential transmission sites may be targeted for preventive actions.

To support local authorities in their efforts to combat the tiger mosquito, the Auvergne-Rhône-Alpes Regional Health Agency (ARS) is providing them with a comprehensive kit that includes technical guides, practical fact sheets, customizable materials, and online training. Find this kit on the ARS website.