Contra Costa Mosquito & Vector Control

FOR IMMEDIATE RELEASE     -     June 17, 2015

Contact: Nola Woods
              Community Affairs Rep.

(925) 771-6158 - office
(925) 250-6502 - mobile 

For human cases, please contact Contra Costa Health Services at 888-959-9911


West Nile virus confirmed in mosquitoes  from Oakley


CONCORD, CALIFORNIA - - The Contra Costa Mosquito & Vector Control District confirmed today that the first group of mosquitoes has tested positive for West Nile virus this year in Contra Costa County. The mosquitoes were found in the Summer Lake area of Oakely. 

"This is not a surprise as we are into the hot months of the year which is the key part of the West Nile virus season and we are already seeing virus activity in surrounding counties," said the District's Scientific Program Manager Steve Schutz, PhD.

What is significant about the first West Nile virus positive mosquitoes of 2015 is that they have been discovered prior to the first infected dead bird of the year. Birds are often the first sign of virus because birds in the Corvidae family are highly susceptible to West Nile virus. 

"We can only test dead birds if we receive reports from members of the public reporting the location of the birds. So far this year, we are getting fewer calls. We definitely could use more," said Schutz.

Dead bird reports from the public are critical in helping the District direct mosquito prevention operations. Members of the public can report dead birds to the state hotline at 1-877-968-2476 (1-877-WNV-BIRD) or by visiting the District's website


Two species of mosquitoes in Contra Costa County capable of transmitting the virus prefer to feed on birds. 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  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, 52 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 2015, a total of one group of mosquitoes, has 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.


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.    


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