SANTA CLARA COUNTY, CALIF. — The first two human cases in 2026 of West Nile virus in Santa Clara County residents have been reported to the County of Santa Clara Public Health Department. The individuals are both adults; one was hospitalized and the other sought care at an emergency department. Both are currently recovering at home. The two individuals are not related to each other and the cases are separate. For reasons of medical privacy, no additional details about the individuals will be released.
Additionally, the Santa Clara County Mosquito and Vector Control District has just detected West Nile virus-positive mosquitoes in areas of the county for the first time this year. Due to this detection, the district will schedule targeted treatments to reduce the adult mosquito population. More information will be available about treatment locations and times at a later date.
Because the individuals are Santa Clara County residents and West Nile virus is a reportable disease in California, the illnesses were reported to the County of Santa Clara Public Health Department. Both cases traveled during their incubation period, so it is unclear if they were infected in Santa Clara County or elsewhere.
“As climate change intensifies, we will continue to see increased mosquito activity, putting all of us at greater risk for mosquito-borne illnesses like West Nile,” said Dr. Krishna Surasi, assistant health officer and communicable disease controller for the County of Santa Clara Public Health Department. “Unfortunately, there is no vaccine that prevents West Nile virus, so please take extra care to prevent these mosquitoes from spreading and infecting people by dumping standing water around your home and property from containers as small as a bottle cap. Use EPA-registered insect repellents, and wear pants and long sleeves, especially if you are outside at dawn and dusk when the mosquitoes that spread West Nile virus are most likely to bite you.”
“Taking swift action is critical to protect public health when a West Nile virus mosquito is detected. Adult-mosquito-control treatments reduce the flying adult mosquito population in the area, which decreases the risk of a West Nile virus-human infection,” said Jeremy Shannon, assistant manager for the Mosquito and Vector Control District.
Mosquitoes can spread West Nile virus through their bites and may cause serious illness in people and certain animals. West Nile virus causes mild to severe flu-like symptoms such as fever, headache, body aches, and in severe cases, neurological symptoms or even death. The incubation period from mosquito bite to onset of disease symptoms is typically two to six days but can last as long as 14 days.
Most people who contract the virus have mild or no symptoms and will recover quickly. However, people over 60 years of age and those with certain medical conditions have a higher chance of getting sick and are more likely to develop complications. Anyone who has been bitten by mosquitoes recently and is experiencing symptoms of West Nile virus should contact a healthcare provider immediately.
Mosquitoes thrive in warm weather, which is why West Nile virus activity typically increases in late summer through early fall. Mosquito and Vector Control District staff routinely monitors and treats areas where mosquitoes breed and tests for mosquito-borne diseases. District staff fulfilled a request from one of the impacted families to conduct a mosquito inspection, treat mosquito breeding sources, and place traps around their home.
How You Can Help
Take the following steps to reduce mosquito populations and lower your risk of getting ill from West Nile virus:
- Dump and drain standing water weekly from containers like flowerpots, buckets and pet bowls and store them indoors or upside down, if they’re not in use.
- Report dead birds, which may be a sign of West Nile virus circulating in the area. Call (877) WNV-BIRD or report online at westnile.ca.gov/report
- Report green or neglected swimming pools and water fountains at vector.santaclaracounty.gov/ReportStandingWater
Stay Informed
To receive future notifications about mosquito treatments and West Nile virus activity:
- Get mosquito alerts at vector.santaclaracounty.gov/SignUp
- Register for AlertSCC, the County’s emergency alert system.
- Follow the district (@sccmvcd) on Instagram, Facebook and X.
The district uses pesticides that are approved and registered by the U.S. and California environmental protection agencies for use in public areas to reduce the mosquito population.
To ask a question, request an inspection, or report high mosquito activity, call the district Monday through Friday, 7:30 a.m. to 3:30 p.m. at (408) 918-4770 or email [email protected].
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