The County of Santa Clara Public Health Department announced that two residents have tested positive for West Nile Virus, marking the first human cases of 2026 among Santa Clara residents.
West Nile Virus is the most common mosquito-borne disease in the contiguous United States, and it is spread via bites from infected mosquitoes. Humans infected with West Nile Virus are not contagious.
“These two cases are a reminder that West Nile Virus can cause very serious illness,” said Dr. Krishna Surasi, assistant public health officer with the Santa Clara County Department of Public Health.
Most people who contract the virus have mild or no symptoms, but people with chronic medical conditions or who are over the age of 60 are at greater risk of serious infection, Surasi said.
Surasi said that both infected individuals have received medical treatment and are currently recovering. They also both traveled domestically prior to infection, so it is unknown if they contracted West Nile while in Santa Clara County, he said.
Earlier this year, West Nile Virus was detected in both birds and mosquitoes in the southern Bay Area.
Santa Clara County will be taking actions to control the adult mosquito population, said Jeremy Shannon, assistant manager of mosquito and vector control for Santa Clara County.
Shannon was unable to share specific details, but said that all pesticides used would be low-dosage and able to break down in sunlight.
Shannon added that Santa Clara County has seen an increase in mosquito population due to this year’s mild winter, early heatwaves and spring rain.
Surasi and Shannon both stressed the importance of staying aware of local mosquito populations. Surasi recommended using effective mosquito repellent, such as those containing picaridin or oil of lemon eucalyptus, and warned against keeping untreated still water that may act as a mosquito breeding ground.
“These first two cases … are an opportunity for (the county) to remind folks about the importance of protecting yourself against mosquitoes this summer,” Surasi said.
Residents can sign up for updates on mosquito control treatments at vector.santaclaracounty.gov/services/mosquito-alerts.
