The two indigenous cases of chikungunya identified in the south of France are "the earliest ever identified" in mainland France during the tiger mosquito season, Public Health France noted on Wednesday, suggesting a possible link with the epidemic in Réunion. For these cases reported in Occitanie, in Prades-le-Lez (Hérault), and in Provence-Alpes-Côte d'Azur, in La Crau (Var), the onset of symptoms dates back to May 27 and June 2 respectively, according to the weekly report of the reinforced surveillance of dengue, chikungunya and Zika in mainland France. "Although decreasing, the pressure of importation into mainland France of cases of chikungunya who had travelled to Réunion may have contributed to the early appearance of indigenous transmission, especially since the strain of the chikungunya virus circulating in Réunion is well adapted to the Aedes albopictus mosquito.", specified Public Health France.
The tiger mosquito is established in 81 departments by the start of 2025
While investigations continue, the health agency indicated that for at least one of the two indigenous cases of this disease, a case from Réunion Island had been identified as possibly the source of local transmission. At this stage, "no episode of indigenous transmission has been highlighted in Europe, outside of France", also pointed out SpF. We speak of an indigenous case when a person contracted the disease on national territory and did not travel to a contaminated area in the 15 days preceding the onset of symptoms.
Read also“It’s huge”: Reunion Island faces a surge in chikungunya cases
Having appeared in mainland France in 2004, the tiger mosquito was present in 81 departments by early 2025. Dengue and chikungunya could become endemic in Europe due to global warming, but also urbanization and travel, all factors that promote the spread of the tiger mosquito, according to a study published in mid-May in the Lancet Planetary Health. From May 1, the start of enhanced surveillance, until June 17, France also recorded 583 imported cases of chikungunya, 395 of dengue fever, and 2 of Zika in mainland France.
In Réunion, Saint-Paul and Saint-Denis are the municipalities with the most cases.
This year, the chikungunya epidemic, a disease causing fever and joint pain, mainly affected Réunion, but is now continuing to decline there. "Reunion Island is currently in a low-intensity epidemic situation.", summarized Public Health France in a specific report on Wednesday. "However, the circulation of chikungunya on the island remains present and marked by disparities depending on the geographical areas.", Saint-Paul and Saint-Denis remain the municipalities with the most cases, the agency added. The number of deaths linked to the epidemic in Réunion is now estimated at 27, with four new deaths attributed to chikungunya, two directly, two indirectly. However, these deaths do not date back to the last few days but to around mid-April, when the outbreak was at its peak. Mayotte, another overseas department in the Indian Ocean, is also affected by an epidemic, declared later and of uncertain magnitude.
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