Mosquitoes Carrying West Nile Virus Detected in Santa Rosa

Release date: 
Oct 3
Cotati, CA-The Marin/Sonoma Mosquito & Vector Control District (District) confirmed additional West Nile virus (WNV) activity in Sonoma County. A mosquito sample tested positive for WNV in the vicinity of Francisco Avenue and Penbrooke Avenue in Santa Rosa. 
The positive sample comes just days after another sample of mosquitoes tested positive in the same vicinity. District officials are warning residents to be vigilant with their personal protection measures this weekend. 

"We expect to see an increase in outdoor activities this weekend while residents are enjoying the last days of summer," stated Nizza Sequeira, Public Relations Director for the Marin/Sonoma Mosquito & Vector Control District. "However, we cannot stress enough the importance of using an effective mosquito repellent that has been tested and proven to protect against disease carrying insects," stated Sequeira.


District personnel scoured the area this past week searching for sources of mosquito production. Additional trapping and surveillance will continue to be conducted in the area around where the positive mosquitoes were found.


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: 29 dead birds, 8 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 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
  • 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.