Chikungunya: eight indigenous cases recorded in mainland France, a level never seen so early in the year

Chikungunya is circulating at an unprecedented level this early in the year in metropolitan France, with eight indigenous cases detected so far, the French Public Health Agency (SPF) reported on Wednesday, June 25. "These indigenous cases, whose first symptoms appeared between May 27 and June 19, are the earliest ever identified in mainland France," the agency emphasized in a weekly report .

An "indigenous case" means that the infected person contracted the disease in mainland France from a tiger mosquito bite – unlike "imported cases," which refer to people who were infected elsewhere before traveling to mainland France. So far, eight indigenous cases have been detected, all in the south of the country: in Hérault, Var, Bouches-du-Rhône, Drôme, Gard, and Corsica.

"Such an early start in the mosquito season and such a high number of outbreaks have never been observed before," insists SPF. Furthermore, SPF says it has established a clear link between several cases that have appeared in mainland France and the ongoing epidemic overseas in Réunion, where some 200,000 residents have been infected since March and around twenty deaths.

"For at least two indigenous cases, the identification of viremic cases [with the presence of the virus in the blood] from Réunion [is] probably the origin of local transmission," the agency emphasizes.

Although we cannot yet speak of an epidemic in mainland France, this observation fuels fears of epidemic transmission between Reunion Island and mainland France. This risk has been raised by health authorities for several weeks. It is all the more heightened with the return of high temperatures in mainland France. High temperatures contribute to the circulation of the tiger mosquito, a phenomenon exacerbated by global warming.

In Réunion, the epidemic is easing with the arrival of the southern winter, but another chikungunya epidemic is underway in Mayotte. However, its extent is difficult to determine, as authorities believe the number of reported cases is likely lower than the actual number.