Ticino health authorities reported the first locally acquired human West Nile virus (WNF) infection in Switzerland on 4 December 2025, in a resident who developed meningoencephalitis after mosquito exposure during summer. Previous detections of WNV in mosquitoes in Ticino suggested an established seasonal risk.
The following precautions are recommended:
- Protect yourself against mosquito bites during the day and at night (see Factsheet: Optimal mosquito and tick bite protection 24/7). Do not touch sick or dead birds, as they may also be infected.
- If you have visited a West Nile fever transmission area, do not donate blood for at least 28 days after returning.