Key Points

• Between 2022 and 2025, 567 cases of arboviral diseases were reported in Normandy, including 279 during periods of enhanced surveillance. These reports have been increasing over the years. 
• The cases are exclusively imported (except for one case of West Nile virus in 2025). 
• They originate primarily from the French West Indies. 
• The Seine-Maritime department (since the 2023 season) is considered to have a low population of tiger mosquitoes (only one municipality). 
• The majority of cases are concentrated in this same department.