Home East County West Nile Virus Infected Mosquitoes Prompt Spraying in Discovery Bay and Martinez

West Nile Virus Infected Mosquitoes Prompt Spraying in Discovery Bay and Martinez

by ECT


CONCORD, CALIFORNIA – – The Contra Costa Mosquito & Vector Control District confirmed today that two more groups of mosquitoes and three additional birds tested positive for West Nile virus. The District will fog for adult mosquitoes Wednesday morning in Discovery Bay and Wednesday evening along the Martinez waterfront.


The recent infected mosquitoes were trapped in Discovery Bay and Martinez. The birds were found in Antioch, Brentwood and Oakley. All 2014 West Nile virus activity and locations can be found on the District’s website.

“Our surveillance efforts indicate that fogging is necessary to protect people,” said the District’s Public Affairs Manager Deborah Bass. “Once the adult mosquitoes have the virus, they are capable of infecting people. It only takes one bite and everyone is susceptible.”

Fogging notifications with interactive maps are available via email to those who sign up for the service. The information is also available on the District’s website, as well as a history of areas fogged.

“We can’t stress enough the importance of heeding our advice to take all of the necessary precautions against mosquito bites,” Bass added. “West Nile virus is grossly underreported and many more people suffer from it than is documented.”

Birds are the reservoir for West Nile virus. The two species of mosquitoes in Contra Costa County capable of transmitting the virus prefer to feed on birds; however, people can become infected when a mosquito bites an infected bird and then a person. West Nile virus symptoms of the mild form include fever, headache, tiredness, body aches, and swollen lymph glands. While the illness can last only a few days, even healthy people have reported being sick for several weeks. West Nile virus of the severe form can be fatal.

Residents are urged to help 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 against mosquitoes by using repellents containing DEET, Picaridin, or Oil of Lemon Eucalyptus.
  • Avoid being outdoors when mosquitoes are present, typically dawn and dusk.
  • Report neglected swimming pools by calling 925-771-6195 or visiting www.ContraCostaMosquito.com  Anonymous calls accepted. Just one neglected pool 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. All reports are crucial, even if the bird does not meet criteria for testing.

Since 2005, 47 people in Contra Costa County have been diagnosed with West Nile virus. In 2006, two people died from the disease. Recent studies have shown that the majority of cases are not diagnosed and are grossly underreported. For 2014, a total of three groups of mosquitoes, four chickens and 14 dead birds have tested positive for the virus.  

Visit the District’s website or click on these links for current West Nile virus activity  or to receive automatic emails for when the District fogs for adult mosquitoes.

Mosquito Samples: 3

nDate ReportedCityCross StreetsSpecies
16/23/14KnightsenHolland Tract AreaCulex tarsalis
27/7/14Discovery BayCherry Hills Dr.Culex pipiens
37/7/14MartinezI-680 x Waterfront Rd.Culex tarsalis

Dead Birds: 14

nDate ReportedCityCross StreetsSpecies
14/23/14AlamoDanville Blvd. x Camille Ave.American Crow
25/18/14Pleasant HillMonument Blvd. x Mohr Ln.American Crow
36/9/14San RamonNorris Canyon Rd. x Bollinger Canyon Rd.American Crow
4614/14OakleyEmpire Ave. x Main St.American Crow
56/17/14OakleyEmpire Ave. x Hemlock Dr.American Crow
66/17/14OakleyEmpire Ave. x Hemlock Dr.American Crow
76/20/14BrentwoodLone Tree Wy x O’Hara Ave.American Crow
86/25/14AntiochHillcrest Ave. x Sunset. Dr.American Crow
96/26/14San RamonBollinger Canyon Rd. x Norris Canyon Rd.American Crow
107/2/14Bethel IslandBethel Island Rd. x Gateway Rd.American Crow
117/9/14Walnut CreekArroyo Wy. x N. BroadwayAmerican Crow
127/10/14OakleyKay Ave. x O’Hara Ave.Western Scrub Jay
137/13/14AntiochCamby Rd. x G St.Western Scrub Jay
147/14/14BrentwoodFoothill Dr. x Balfour Rd.American Crow

Sentinel Chicken Flocks: 1

# of Chickens out of 10 (10 per Flock)Date BledArea
1/106/16/14Holland Tract
3/106/30/14Holland Tract

Horses: 0

nDate ReportedCityDead/Euthanized

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 their office between 8:00 a.m. and 4:30 p.m. to get FREE mosquitofish for ornamental ponds, horse troughs or neglected swimming pools. 

You may also like