Officials urge precautions as West Nile virus detected in East Contra Costa mosquitoes

Mosquitoes in Knightsen have tested positive for West Nile virus, the first detection in Contra Costa County this year. Two weeks earlier, a California scrub jay in San Ramon also tested positive, highlighting the virus's impact on local avian populations. In California, seven human cases have been reported in 2025, with one fatality in Tulare County, raising concerns about the virus's spread among residents. Last year, a man from east Contra Costa County died from West Nile virus, marking the first county death from the disease since 2006. Steve Schutz, scientific program manager for the Contra Costa Mosquito and Vector Control District, urged residents to take precautions against mosquito bites, such as using EPA-registered insect repellents.

The district recommends repellents containing DEET, Picaridin, or Oil of Lemon Eucalyptus. Reporting dead birds is a crucial method for tracking the virus's spread, according to public health officials. Residents can contact the district for assistance with mosquito issues or questions regarding West Nile virus.