Map: West Nile Virus Intensifies In Contra Costa County

CONTRA COSTA COUNTY, CA — The Contra Costa Mosquito and Vector Control District reported Friday that two more dead birds and two more groups of mosquitoes have tested positive for West Nile virus in Contra Costa County.

One dead bird was an American crow from San Ramon and the other was a California scrub jay from Concord. The mosquitoes were trapped in Pittsburg and Oakley.

Five dead birds and five groups of trapped mosquitoes in the county have tested positive for WNV thus far in 2023. The map below shows the locations of the dead birds with blue markers and the trapped mosquitoes with red markers.

"While we are seeing more virus activity in East Contra Costa County right now, the risk of West Nile virus is not necessarily restricted to that area," said Steve Schutz, scientific program manager for the District. "Dead birds from Central Costa County have also tested positive for the virus and as warm temperatures continue, we expect West Nile virus activity to continue. To reduce the risk of West Nile virus, it should be a priority for Contra Costa County residents to protect themselves from mosquitoes and mosquito bites."

WNV can be transmitted to birds, other animals, and people through a single mosquito bite. To reduce the risk of mosquitoes and mosquito bites, the District advised residents to:

• Wear an EPA-registered insect repellent that includes one of the four most effective active ingredients: DEET, Picaridin, IR3535, or the repellent version of Oil of Lemon Eucalyptus
• Dump out standing water and scrub the inside of the container to remove mosquito eggs
• Make sure door and window screens are in good working condition
• Contact the District to request mosquito service
• Report dead birds to the California West Nile Virus Dead Bird Call Center

The District said that as Contra Costa County residents take steps to reduce the risk of WNV, the District will conduct surveillance and control as needed in the areas where the dead birds and mosquitoes were found.

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

Since 2005, 75 people in Contra Costa County have been diagnosed with West Nile virus. In 2006, two people died from the disease. No human cases have been reported so far this year in the county.

As of Friday, 14 human cases of West Nile virus have been reported this year in California — six of which were reported this week. Of the 14 cases, none were fatal. Eight counties — Butte, Kern, Madera, Merced, Riverside, San Bernardino, San Joaquin and Tulare — have reported human cases. For further information, visit Westnile.ca.gov.