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Mosquitoes in Lake County Test Positive for West Nile Virus

LAKEPORT, Calif. – For the first time this year, mosquitoes have tested positive for West Nile virus in Lake County.

The mosquitoes, Culex tarsalis (western encephalitis mosquito), were collected in traps near Upper Lake on July 21, 2021.

“West Nile virus activity is increasing statewide, including in Lake County,” said Jamesina Scott, Ph.D., District Manager and Research Director of the Lake County Vector Control District. “This serves as a reminder to avoid mosquito bites to avoid West Nile virus,” Scott said. “Mosquitoes thrive in still water. Dump out or drain water in backyard water sources, or contact the District for free mosquito-eating fish for water that can’t be drained, like unmaintained (green) swimming pools and spas, ornamental ponds, or animal watering troughs,” she advised residents.

The District encourages residents to reduce their risk of contracting West Nile virus and other mosquito-borne diseases:

Dump or drain standing water to prevent mosquitoes. Mosquitoes need water to complete their life cycle.
Defend yourself. Use repellents containing DEET, Picaridin, IR3535, or Oil of Lemon Eucalyptus. Follow the label directions.
• Avoid being outdoors when mosquitoes are present, typically dawn and dusk.

So far this year, West Nile virus activity has been detected in one mosquito sample in Lake County. Statewide, 21 California counties have detected WNV this year, mainly in mosquito samples. As of July 23, 2021, three human cases of West Nile virus illness have been reported in California residents this year. For more information about West Nile virus, visit

Lake County Vector Control District provides mosquito control services to our community. If you would like help with a mosquito problem, including reporting a neglected pool or spa, or have an in-ground yellowjacket nest on your property that you want treated, please contact the Lake County Vector Control District at (707) 263-4770 or submit a service request on their website at
Water Faucet
Urgent Health Advisory

Effective immediately, people on private water systems whose tap water comes from their own private intake into the lake, in the Oaks Arm and Lower Arm of Clear Lake should not drink the water.

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