The First West Nile Virus Positive Dead Bird Of 2023 in Contra Costa County

One week after mosquitoes test positive for West Nile Virus in Contra Costa County, the first dead bird tests positive.

CONCORD, CA (July 22, 2023) — The Contra Costa Mosquito and Vector Control District reports the first dead bird of the year has tested positive for West Nile virus (WNV) in Contra Costa County. The dead bird, a California scrub jay, was picked up from Brentwood. This happened just one week after two mosquito samples from Discovery Bay tested positive for WNV.

Infected mosquitoes can transmit WNV to birds, other animals, and people through a single mosquito bite. The District advises county residents to take steps to avoid mosquito bites and reduce the risk of WNV. Precautions include

  • Dumping out standing water and scrubbing the inside of the container to remove mosquito eggs.
  • Wearing long sleeves and long pants to reduce the amount of exposed skin.
  • Wearing insect repellent when outside during the hours before and after dawn and dusk.

According to the CDC, when used as directed, EPA-registered insect repellents are proven safe and effective. The District recommends using EPA-registered insect repellents with one of the following active ingredients:

  • DEET
  • Picaridin
  • The repellent version of Oil of Lemon Eucalyptus
  • IR3535

Always follow the instructions on the label when using insect repellent.

Reducing risk

District employees continue to work to reduce the risk of mosquito-borne illness in Contra Costa County. They will conduct surveillance that includes trapping and testing mosquitoes.

“The mosquito traps we use are a combination of semi-permanent traps set in specific locations in Contra Costa County and temporary traps that we set in various areas of the county as needed to assess mosquito risk. On a weekly basis, we collect the traps, identify and count the mosquitoes from the traps and test the mosquitoes. And as we find infected mosquitoes or dead birds that test positive for WNV, we conduct inspections and treatments as necessary to nearby public areas including parks and underground sources including catch basins,” said Steve Schutz, Ph.D., Scientific Program Manager.

Contra Costa County residents can report dead birds by phone at (877) WNV-BIRD (968-2473) or online. County residents can also request mosquito service for their residential properties by calling (925) 685-9301 or online.

Since 2005, 75 people in Contra Costa County have recieved a diagnosis of West Nile virus. In 2006, two people died from the disease. For human case information, please visit the California Department of Public Health Vector-Borne Disease Section online.

Contra Costa Mosquito & Vector Control District, an independent special district and public health agency, 155 Mason Circle in Concord.