Blood donor tests positive for West Nile Virus in Fresno County

FRESNO COUNTY, Calif. (KSEE/KGPE) – A Fresno County blood donor became the first confirmed human case of West Nile Virus in the county in 2025.

The Fresno County Department of Public Health said Friday the infection was identified through routine testing of a blood donor in Fresno County; health officials warn the number of cases is expected to increase, as it is still peak mosquito season in the county.

The California Department of Public Health reports that there have been seven human West Nile Virus cases in California in 2025 as of Aug. 1. The cases include one death.

In 2024, there was a total of 132 cases reported in the state, including 12 deaths.

To reduce the risk of being bitten by mosquitoes and contracting the virus, residents are urged to follow these precautions:

• Apply an insect repellent that contains DEET, picaridin, oil of lemon eucalyptus, or IR 3535, especially at dawn and dusk when mosquitoes are most active.
• Make sure that doors and windows have tight-fitting screens to keep out mosquitoes and repair or replace screens that have holes.
• Eliminate standing water and containers that can hold water from around the home.
• Contact your local Mosquito Abatement District (MAD) to report poorly maintained swimming pools or water features that appear green.

Residents can also click here for more information.

Health officials add that dead birds can serve as an indicator of the virus’ presence in the community. To report a dead bird, click here or call 1-877-WNV-BIRD.