West Nile Virus Detected In Local Mosquito Population

Release date: 
Oct 1

Cotati, CA - The Marin/Sonoma Mosquito & Vector Control District (District) confirmed additional West Nile virus (WNV) activity in Sonoma County.  A mosquito sample and a dead bird collected near Dancing Penny Way in Santa Rosa both tested positive for WNV. In addition, a sentinel chicken from Cloverdale tested positive for antibodies to the virus.

"The spike in temperatures could mean an increase in virus activity, and because the virus has been detected in the adult mosquito population taking personal protection measures against bites is crucial," stated Nizza Sequeira, Public Relations Director for the Marin/Sonoma Mosquito & Vector Control District. "We are urging residents to report all mosquito problems in their area to our District. The sooner we are aware of problems the faster we can respond, thereby decreasing the risk of West Nile virus transmission."

The Centers for Disease Control recommend using repellents that contain one of the following active ingredients: DEET, picaridin, IR3535, or oil of lemon eucalyptus (PMD). These active ingredients are EPA registered and have been studied and tested to make sure they are effective and safe (when used according to label directions).  Other personal protection measures include wearing long sleeve shirts and long pants.

2014 West Nile virus activity:

Marin County: 5 dead birds and 3 mosquito samples have tested positive for West Nile virus to date.

Sonoma County: 26 dead birds, 7 mosquito samples, 1 equine case, and 3 sentinel chickens have tested positive for West Nile virus to date.

Simple ways to help reduce exposure to mosquitoes and lessen the risk of WNV:

  • Eliminate standing water in rain barrels, old tires, buckets, kiddie pools or any other item that can hold water for more than 72 hours. 
  • Check septic tank lids to ensure a tight seal and repair any visible cracks.
  • Screen septic tank vent pipes using a fine mesh screen.
  • Report mosquito problems, neglected swimming pools, or any area that could be producing mosquitoes at  www.msmosquito.com or 1-800-231-3236.
  • 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 or online at www.westnile.ca.gov.
  • 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. 
  • Residents interested in staying informed about district activities are encouraged to follow MSMVCD on twitter and facebook.

West Nile virus 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 (about 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.