Contra Costa Mosquito & Vector Control

FOR IMMEDIATE RELEASE     -     July 1, 2014

Contact: Deborah Bass
               Public Affairs Mgr.

(925) 771-6112 - office
(925) 260-4670 - mobile 

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


West Nile virus confirmed in mosquitoes and chicken from Holland Tract and in three more dead birds in county 


CONCORD, CALIFORNIA - - The Contra Costa Mosquito & Vector Control District confirmed today that a group of mosquitoes and a chicken testing positive for West Nile virus were found in Holland Tract, an area near Brentwood. Three dead American crows also tested positive for the virus and were found in Antioch, Brentwood and San Ramon. This is the first group of mosquitoes and first chicken that have tested positive this year in Contra Costa County.


"This is not surprising given the amount of West Nile virus activity in our neighboring counties right now," said the District's Public Affairs Manager Deborah Bass. "West Nile virus is extremely active and our message is - take precautions against mosquito bites seriously. Wear mosquito repellent and avoid being outside at dawn and dusk when mosquitoes are present. It only takes one bite from an infected mosquito to transmit the virus. And anyone of any age can contract the virus."


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  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 one group of mosquitoes, one chicken and nine 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.


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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