Lessons from an investigation of an autochthonous chikungunya outbreak in Bergerac, mainland France, June to October 2025.

In 2025, an unprecedented number of autochthonous chikungunya transmission events occurred in mainland France. One of the largest outbreaks took place in Bergerac (south-west France). By 27 October, 100 locally acquired cases were identified. They had symptom onsets between June and October. Our data suggest that door-knocking surveys and vector control measures assisted in slowing the virus spread. Autochthonous outbreaks of mosquito-borne diseases are expected to become more frequent with climate change, so improving outbreak control is crucial.