Montpellier Chikungunya, dengue fever, West Nile virus: in 2025, France will face unprecedented viral circulation Montpellier , The explosion in the number of mosquito-borne virus infections in France makes 2025 a truly exceptional year. This grim record is primarily due to the highly active circulation of the chikungunya virus, but our country is also facing a more limited, but nonetheless significant, circulation of dengue and West Nile viruses. We are therefore facing, for the first time, a triple circulation of these viruses called arboviruses . This dual problem—a significant increase in the number of infections and a diversity of circulating viruses—creates a particularly complex situation. How to describe the 2025 season? Exceptional? Unprecedented? Unexpected? While the first two adjectives are undoubtedly appropriate, the last proves inaccurate, as specialists in the field have been warning for several years about the foreseeable, even inevitable, risk of the permanent establishment of these viruses, once confined to tropical regions, in our latitudes. France is not the only country affected: Italy, Spain and other European countries are also recording a …