Additional West Nile Virus Activity in Marin and Sonoma Counties

Release date: 
Oct 9

Cotati, CA - The Marin/Sonoma Mosquito and Vector Control District (District) received confirmation from the California Department of Public Health (CDPH) that six additional dead birds have tested positive for West Nile virus (WNV). The dead birds were collected from Santa Rosa, Cloverdale, Ross, Sonoma, Petaluma and Sebastopol. While all of the birds tested positive for WNV, lab results confirmed that only two had been recently infected with the virus; one near N. Cloverdale Blvd. in Cloverdale and the other near Walters Rd. in Ross.

"The heat wave we experienced over the last few weeks was a contributing factor for the amplification and transmission of the virus,” said Nizza Sequeira, Public Relations Director for the Marin/Sonoma Mosquito and Vector Control District. “While the weather forecast calls for mild weather with chances of light rainfall, it doesn’t mean that mosquito season is over yet, and residents should continue to use personal protection measures and report mosquito problems,” said Sequeira.

Residents can help reduce the threat of WNV in the following ways:

  • Eliminate standing water in rain barrels, old tires, buckets, kiddie pools or any other item that can hold water for more than a week.
  • Report mosquito problems, neglected swimming pools, or any area that could be producing mosquitoes.
  • Stock backyard ponds or other permanent water features with mosquitofish. The fish are free and can be delivered or simply picked up at the District office.
  • Report dead birds to the West Nile Virus Hotline at 1-877-968-2473.
  • Wear mosquito repellent when outdoors at dusk and dawn. Use a repellent containing one of the following active ingredients: DEET, Picaridin, oil of lemon eucalyptus, or IR3535.

West Nile virus (WNV) is a mosquito-borne disease that is spread by the bite of an infected mosquito. Mosquitoes become infected when they feed on infected birds. Infected mosquitoes can then spread the disease to humans and other animals.

Less than 1% of people (1 in 150) infected with WNV develop serious illness. These cases may last for extended periods of time, result in permanent neurological damage and may be fatal. Approximately 20% of people (about 1 in 5) infected with WNV experience mild symptoms that may include fever, headache, body aches, nausea, rashes, swollen lymph nodes and vomiting. Approximately 80% of people (about 4 out of 5) infected with WNV do not show any symptoms.

For more information or to report mosquito problems contact the Marin/Sonoma Mosquito and Vector Control District at 1-800-231-3236 or visit

Report dead birds to the West Nile Virus Hotline at 1-877-968-2473, or online at

The Marin/Sonoma Mosquito and Vector Control District is an independent, special district committed to protecting public health from mosquitoes and mosquito-borne diseases. All programs and services are funded through property taxes and are provided to all residents of Marin and Sonoma counties. For more information about us please visit our website at or call 1-800-231-3236.