West Nile Virus Surveillance

The District’s West Nile virus surveillance program reports several types of positive West Nile virus results, including dead birds, mosquito samples (“pools”), sentinel chickens, and human cases.

For more information about the District’s West Nile virus and mosquito population surveillance, visit the Mosquito Surveillance page.

For current West Nile virus data for California, visit the California Vectorborne Disease Surveillance Maps (CalSurv) page.

Current West Nile Virus Information for San Mateo County

In 2023, no mosquito pools tested positive for West Nile virus in San Mateo County. No sentinel chickens tested positive for West Nile virus. In 2023, a total of 14 dead birds tested positive for West Nile virus in San Mateo County.

West Nile Virus Dead Bird Hotline

The California Department of Public Health (CDPH) West Nile Virus Dead Bird Hotline is an important part of West Nile virus surveillance. Residents who find a dead bird in good condition should file a report online. The District receives reports of dead birds year-round from CDPH and will collect and test suitable birds in any season.

A blue background with brown soil ground. Three dark brown chickens peck at the ground.

West Nile Virus Season and Surveillance Efforts

Surveillance for West Nile virus begins in California each year in April. The District protects residents from this mosquito-borne disease with control that targets mosquitoes in the larval stage, mosquito population monitoring, disease surveillance and public education. The laboratory staff conduct surveillance to detect the presence of mosquito-borne disease in three main ways:

West Nile Virus, Previous Years' Data

For older or more comprehensive data, please contact us at info@smcmvcd.org

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