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First Detection of West Nile Virus for 2020

Cotati, CA.  September 18, 2020-The Marin/Sonoma Mosquito and Vector Control District has confirmed finding the first dead bird infected with West Nile virus (WNv) for 2020. The American Crow was collected near Nantucket Cove and Catalina Blvd. in San Rafael and is the first detection of West Nile virus activity for the 2020 season.

"A positive dead bird provides an early warning of increasing virus activity in birds and mosquitoes,” said Nizza Sequeira, Public Information Officer for the Marin/Sonoma Mosquito and Vector Control District. "Residents can help in the fight against West Nile virus by continuing to report dead birds to the West Nile Virus Hotline at, reducing mosquito production on their properties and reporting mosquito problems." 

District staff will continue to trap, test, and monitor the abundance of adult mosquitoes in the area and perform control operations as necessary. Vector control technicians are inspecting all documented sources of mosquito production as well as checking for new sources.

West Nile Virus infection can cause serious disease, including inflammation of the brain and central nervous system. Marin County clinicians are required to report West Nile Virus cases to Marin Public Health. “Last year, we were fortunate not to have any human cases in Marin, but the presence in birds shows we’re at risk.” Said Danielle Hiser-Honda, Marin County Public Health nurse. “It’s important to take precautions to limit the mosquito population, and to prevent bites.”

The Marin/Sonoma Mosquito and Vector Control District, in accordance with the California Department of Public Health, recommends repellents that contain one of the following active ingredients:

  • DEET
  • Picaridin
  • Oil of lemon eucalyptus 
  • IR3535

Other ways to protect yourself from mosquitoes and mosquito bites include:

  • Stock permanent water features with mosquitofish (available for free from our District)
  • Be sure to properly screen and/or secure lids on rain barrels or water storage containers
  • Do not over-water lawns
  • Clean out bird baths and animal water bowls at least twice a week
  • Keep swimming pools and hot tubs properly chlorinated
  • Make sure that septic tank lids are properly sealed and vent pipes are screened
  • Report mosquito problems at 707-285-2200 or online at


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