Santa Clara County Vector Control will spray in parts of the City of Santa Clara and San Jose on Tuesday evening after the first two human cases of West Nile and the first mosquito with the virus were detected in late July.

On Aug. 4, starting around 10 p.m., Vector Control will spray in the following zip codes: 95050, 95051, 95117, 95126 and 95128.

In the City of Santa Clara, the affected areas include the areas around Westfield Valley Fair, Pruneridge Golf Club, both Mission City Memorial Park and Santa Clara Catholic cemeteries, Santa Clara University and downtown Santa Clara. You can find an interactive map here.

Santa Clara County officials say that because of the emergence of West Nile, they will start targeted treatments to reduce the adult mosquito population.

The treatments in the City of Santa Clara and San Jose on Tuesday are just one of many planned.

Santa Clara County health officials say the two people who contracted West Nile are Santa Clara County residents. They are adults and are recovering at home but may have contracted the virus outside of the county because both had traveled during their incubation period.

Whether it was contracted in Santa Clara County or elsewhere, county officials want residents to take steps to prevent West Nile from spreading.

“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,” said Dr. Krishna Surasi, assistant health officer and communicable disease controller for the County of Santa Clara Public Health Department. “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.”   

West Nile virus may cause serious illness in people and certain animals. It can cause 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 a mosquito bite to onset of virus 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.

If you have been bitten by mosquitoes recently and are experiencing symptoms of West Nile virus, contact a healthcare provider immediately.

Santa Clara County did not have to spray in the City of Santa Clara last year, but did spray in parts of the City of Santa Clara in 2024 after West Nile was detected.