Key Points

• Chikungunya has entered the epidemic phase in Mayotte (Phase 3 of the ORSEC arbovirus plan) since May 27, reflecting intense and widespread transmission of the chikungunya virus throughout the territory

• A total of 560 confirmed cases of chikungunya were recorded between weeks 10 and 21 of 2025. The epidemic continues

• Circulation of chikungunya throughout the entire territory of Mayotte, with a persistent concentration of cases in the municipalities of Mamoudzou, Pamandzi, and Dzaoudzi

• Adaptation of the surveillance strategy around four pillars: laboratory-confirmed cases, syndromic surveillance (emergency departments), surveillance of hospitalizations, and severe cases

• Possible underestimation due to the lack of systematic use of biological confirmation tests for chikungunya in emergency departments and private practice, as well as limited access to care among part of the population

• A temporary increase in dengue circulation on the island, with 21 confirmed cases since the beginning of the year