Contra Costa Mosquito & Vector Control

FOR IMMEDIATE RELEASE     -     August 22, 2012

Contact: Deborah Bass
              Public Affairs Mgr.

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


First infected chickens of 2012


CONCORD, CALIFORNIA - - The Contra Costa Mosquito & Vector Control District announced today that two groups of mosquitoes from Brentwood have tested positive for West Nile virus, as well as three chickens from Holland Tract, and seven birds. Four birds were located in Brentwood, and one each from Antioch, Pleasant Hill, and Walnut Creek. Fogging for adult mosquitoes is planned  for Thursday, August 23 in Brentwood. 


"Once we determine there is a risk to people, we act immediately to protect their health," said District Operations Manager Carlos Sanabria.


District employees are working diligently to find sources of mosquitoes, however the search has been challenging because the mosquitoes that have tested positive today are associated with backyard sources.  


"Most of our positive mosquitoes so far this year have been Culex pipiens, which are primarily associated with underground sources," said Steve Schutz, Ph.D., the District's scientific program manager. "The most recent group to test positive is the Culex tarsalis, which are primarily associated with backyard and other sources." 


Residents are urged to wear mosquito repellent when outdoors, especially at dawn and dusk when mosquitoes are present.


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. 

Less than one percent of individuals (about 1 in 150 people) infected with West Nile virus will develop severe illness. The severe symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. These symptoms may last several weeks, and neurological effects may be permanent. West Nile virus infection can be fatal.    


Residents are urged to help reduce their risk of contracting mosquito-borne diseases by following these guidelines: 

  • Don't produce mosquitoes on your property. Dump or drain standing water. Mosquitoes can't begin their life without water.
  • Defend yourself against mosquitoes 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.  
The District makes every effort to notify residents about West Nile virus activity and adult mosquito spraying events. People wishing to be notified about adult mosquito spraying in residential areas have several options. They may visit the District's website and opt to receive the maps and notifications automatically by email.There is also an option to receive media releases and the Mosquito Bytes newsletter. These communications are posted directly on the District's website. Spray schedules are also available by calling the District at (925) 771-6195 and listening to a recorded message. 

Since 2005, 39 people in Contra Costa County have been diagnosed with West Nile virus. In 2006, two people died from the disease. A recent study has shown that the majority of cases are undiagnosed and grossly under reported. This year, a total of nine groups of mosquitoes, 21 dead birds, and three chickens have tested positive for the virus. A list of the  current West Nile virus activity can be found on the District's website.

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.  

For information concerning human West Nile virus symptoms, prevention, or testing, please call the Contra Costa Health Services department at (888) 959-9911. For information concerning West Nile virus and horses, please call the California Department of Food and Agriculture Animal Health Branch at (916) 654-1447. 

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