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More West Nile Virus Positive Mosquitoes Confirmed in Lake County

LAKEPORT, Calif. – The Lake County Vector Control District confirmed that six more mosquito samples from Lake County tested positive for West Nile virus this week.  The positive mosquitoes were collected from Clearlake Oaks, Spring Valley, and Upper Lake.

“Warm overnight temperatures are ideal for increasing West Nile virus and mosquito activity,” said Jamesina Scott, Ph.D., District Manager and Research Director of the Lake County Vector Control District.  “Mosquitoes transmit West Nile virus.  If you are outside around dusk or dawn, use a mosquito repellent that contains Picaridin, IR3535, Oil of Lemon Eucalyptus, or DEET.”
West Nile virus is endemic in California, and the summer heat can increase virus activity and mosquito populations. In Lake County this year, a total of 11 samples of mosquitoes tested positive for West Nile virus (WNV).  The positive mosquitoes were collected near Clearlake Oaks (3), Lower Lake (1), Middletown (1), Spring Valley (1), and Upper Lake (5).

WNV is transmitted to people and animals through the bite of an infected mosquito.  There is no cure for WNV. One in five persons infected with the virus will exhibit symptoms.  Symptoms can include fever, headache, body aches, nausea, or a skin rash.  These symptoms can last for several days to months. One in 150 people infected with the virus will require hospitalization. Severe symptoms include high fever, muscle weakness, neck stiffness, coma, paralysis, and possibly death.
Mosquitoes develop in water.  Residents should take the following precautions to help reduce the chances of getting bit by mosquitoes:

• Dump and drain any containers filled with water at least once a week
• Clean and scrub bird baths and pet water bowls weekly
• Dump water from potted plant saucers
• Do not transport or share plant stems rooted in water
• Drill a hole or puncture containers to eliminate standing water

For water sources that can’t be drained, like a pond, livestock watering trough, water feature, or an out-of-service (green) swimming pool, residents should contact the District for free mosquito-eating fish to prevent mosquitoes from growing there.

To prevent mosquito bites, the District offers the following tips:

• Apply mosquito repellents to exposed skin before going outdoors; reapply as recommended
• Wear repellent containing Picaridin, IR3535, DEET, or oil of lemon eucalyptus
• Close all unscreened doors and windows to prevent mosquitoes from entering your home or space; repair broken or damaged screens
• Wear long-sleeved shirts and long pants, and opt for lighter-colored clothing 

Statewide, this year 29 California counties have detected WNV, mainly in mosquitoes. As of August 21, 2020, twenty-seven human cases of West Nile virus illness have been reported in California residents.

Residents with questions or who would like help with a mosquito problem, including reporting a neglected pool or spa, or have an in-ground yellowjacket nest on their property that they want treated, should contact the Lake County Vector Control District at (707) 263-4770 or submit a request online at
For more information about West Nile virus, visit  Information about mosquito repellents can be found on the US Centers for Disease Control and Prevention website at

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