First West Nile virus case detected in Bay Area mosquitoes this year

A mosquito in Newark has tested positive for West Nile virus, marking the first detection in the Bay Area this year. The discovery follows reports of dead birds carrying the virus in several nearby counties. The positive mosquito sample was collected from a trap in Newark and confirmed at the Alameda County Mosquito Abatement District’s laboratory on Friday. Between April and June, five dead birds in the same area also tested positive for the virus.

Across California, there have been 34 positive mosquito samples and 35 dead birds with West Nile virus so far. In Santa Clara County, dead birds with the virus were found in Los Altos, Palo Alto, and San Jose.

In response, the district is increasing mosquito surveillance and treating standing water in the affected zone. Residents between Christine Street and Cherry Street, near Mayhew Landings Park, will notice more mosquito traps and district vehicles. Unmaintained swimming pools remain a major breeding ground for mosquitoes in the county. West Nile virus spreads to people and animals through infected mosquito bites. Most infected individuals show no symptoms, but around one in five develop illness, and fewer than 1% face severe neurological effects. Authorities are urging vigilance to reduce mosquito populations and prevent further spread.