Genomic insights into the re-emergence of chikungunya virus on Réunion Island, France, 2024 to 2025
Étienne Frumence, Géraldine Piorkowski, Nicolas Traversier, Rayane Amaral, Muriel Vincent, Ambroise Mercier, Nazlı Ayhan, Laurent Souply, Laura Pezzı, Clément Lier, Gilda Grard, Guillaume André Durand, Xavier Deparis, F. Thouillot, Xavier de Lamballerie, Raphaëlle Klitting, Marie‐Christine Jaffar‐Bandjee
Abstract
Chikungunya virus re-emerged on Réunion Island in August 2024, 18 years after a first major outbreak. Analysis of 173 genomes from the current epidemic reveals a monophyletic clade with mutations linked to adaptation to Aedes albopictus mosquitoes, including E1-A226V. Bayesian inference suggests only brief cryptic circulation before detection. The same lineage was also detected on Mayotte Island in March 2025. Continued spread and confirmed travel-related cases in mainland France and globally highlight the risk of wider regional and international dissemination.