West Nile Virus Confirmed in Mosquitoes, Birds in Contra Costa County

Photo provided by Contra Costa Mosquito Vector Control
CONCORD, CALIFORNIA – – The Contra Costa Mosquito & Vector Control District confirmed today that one group of mosquitoes from Oakley and three dead birds have tested positive for West Nile virus. The birds were from Brentwood, Antioch, and Pleasant Hill.
“The mosquitoes and birds that have tested positive this week demonstrate West Nile virus does not end with Labor Day. Citizens should remain vigilant,” says the District’s Scientific Programs Manager Steve Schutz, Ph.D. “Dump out standing water. Use mosquito repellent. And report dead birds because they help us know where to look for West Nile virus.” 
District personnel are conducting extra surveillance and mosquito control in the areas where the virus activity was found.
The District urges the public to report dead birds to the state hotline: 1-877-968-2473. Birds are often the first sign of disease transmission. Even if the birds are not tested, the reports alone yield crucial information to protect public health.
Residents can reduce their risk of contracting mosquito-borne diseases by following these guidelines:
  • Dump or drain standing water. Mosquitoes can’t begin their lives without water.
  • Defend yourself – use repellents containing DEET, Picaridin, or Oil of Lemon Eucalyptus.
  • Avoid being outdoors when mosquitoes are present, typically dawn and dusk.
  • Maintain neglected swimming pools. Just one can produce more than 1 million mosquitoes and affect people up to five miles away.
  • Report dead birds to the state hotline: 1-877-968-2473 or by visiting the California Department of Public Health’s website. All reports are crucial.

Since 2005, 56 people in Contra Costa County have been diagnosed with West Nile virus. In 2006, two people died from the disease. For a current list of West Nile virus activity this year, visit this page on the District’s website.  For human case information, please contact Contra Costa Health Services at 888-959-9911.


Mosquito Samples: 6

n Date Reported City Cross Streets Species
1 7/26/17 DIscovery Bay Point of TImber Rd. x Poe Dr. Culex pipiens
2 8/2/17 Byron Byron Hwy x Rankin Rd. Culex tarsalis
3 8/16/17 Antioch E. 18th St. x Hillcrest Ave. Culex tarsalis
4 8/21/17 Discovery Bay Cherry Hills Dr. x Hwy 4 Culex pipiens
5 8/23/17 Brentwood Continente Ave x Date Nut St. Culex pipiens
6 9/11/17 Oakley Oakley Rd. x Main St. Culex tarsalis

Dead Birds: 10

n Date Reported City Cross Streets Species
1 7/26/17 Walnut Creek Ygnacio Valley Rd. x Wiget Ln. American Crow
2 7/26/17 Walnut Creek Ygnacio Valley Rd. x Wiget Ln. American Crow
3 8/1/2017 Walnut Creek Ygnacio Valley Rd. x Wiget Ln. American Crow
4 8/3/2017 Danville Brookside Dr. x Greenbrook Dr. American Crow
5 8/8/2017 Discovery Bay Highway 4 x Discovery Bay Blvd. Western Scrub Jay
6 8/24/2017 Danville Camino Tassajara x Fairwood Ct. Western Scrub Jay
7 9/7/2017 San Ramon Davona Dr. x Calais Drive American Crow
8 9/8/2017 Brentwood Byron Hwy. x Delta Rd. American Crow
9 9/10/2017 Antioch Hillcrest Ave. x Via Dora Dr. American Crow
10 9/12/2017 Pleasant Hill Michigan Blvd. x Nebraska Dr. American Crow

Sentinel Chicken Flocks: 1

Note: Chickens do not die from West Nile virus. They develop antibodies to the virus which is detected in their blood.

#/10 Date Bleed Area
4/10 8/7/17 Knightsen

Horses: 1

n Date Reported City Dead/Euthanized
1 8/11/2017 Brentwood No
Contra Costa Mosquito & Vector Control District, an independent special district and public health agency, is located at 155 Mason Circle in Concord. Call the District to report mosquito problems at (925) 771-6195 or visit the office between 8:00 a.m. and 4:30 p.m. to get FREE mosquitofish for ornamental ponds, horse troughs or neglected swimming pools.