Imported chikungunya in French travelers returning from outbreak-affected regions
Eric Plennevaux, Adrianne de Roo, Guenaelle Augier, Gerard T Vonderling, Juan Carlos JaramilloABSTRACT
Background
Outbreaks of chikungunya disease are unpredictable, typically episodic, and explosive. In 2025, several such outbreaks were observed and a marked increase in imported cases of chikungunya to mainland France was reported. This study aimed to describe the rate of chikungunya in French travelers returning from La Réunion, Mayotte, Mauritius, Madagascar, Sri Lanka, and Cuba, all of which showed major chikungunya resurgences in 2025, and to assess the potential burden that CHIKV outbreaks—whether officially notified or not—can cause to travelers.
Methods
Publicly available data from Santé Publique France were used to extract the number of chikungunya cases, and International Air Transport Association data were used for information on the number of flight tickets to estimate traveler numbers. These data were used to derive monthly rates of imported cases of chikungunya to mainland France from January to December 2025.
Results
Trends in rates of chikungunya among travelers returning to mainland France from La Réunion and Mayotte closely mirrored the sharp and compact epidemic curves observed locally. Peak imported rates exceeded 1,800 cases/100,000 travelers (La Réunion [April]) and 400 cases/100,000 travelers (Mayotte [May]) and remained above 100 cases/100,000 travelers for March, April, May, and June (La Réunion) and April, May, and June (Mayotte). For Mauritius, Madagascar, Sri Lanka, and Cuba, estimated peak rates were 248, 338, 90, and 2,480 cases/100,000 travelers, respectively, although it was noted that some outbreaks were not officially notified or were reported late.
Conclusions
Returning travelers to mainland France from regions facing a chikungunya outbreak in 2025 showed a substantial burden of infection and gave rise to local spread of disease, highlighting the importance of robust surveillance systems and timely outbreak notification.