29 Sep West Nile Virus-Infected Mosquitoes Found in East County

A Culex tarsalis mosquito resting on human skin. (James Gathany / Centers for Disease Control via Bay City News)

By Bay City News

Mosquitos that tested positive for West Nile virus have been found on an island in the Sacramento-San Joaquin River Delta in eastern Contra Costa County, officials said Friday.

The mosquitoes collected from a trap in Holland Tract are the second group to test positive for the virus in the county this year, the Contra Costa Mosquito and Vector Control District said.

Infected mosquitos transmit the virus to humans and animals. Serious infection symptoms can include fever, severe headaches, stiff neck, disorientation, or confusion.

A man who lived in eastern Contra Costa County died from West Nile virus in a case reported July 16, 2024. It was the first reported county death from the disease since 2006.

“Although fall is officially here, overnight temperatures are still warm enough for mosquitoes and West Nile virus transmission,” Steve Schutz, the district’s scientific program manager, said in a press release. “Residents should continue to protect themselves from mosquito bites and reduce the risk of mosquitoes on their own properties.”

Residents are encouraged to dump out standing water at least once a week.

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