Contra Costa Mosquito & Vector Control

FOR IMMEDIATE RELEASE     -     August 6, 2015

Contact: Deborah Bass
                Public Affairs Manager

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

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


Four more chickens test positive east of Knightsen


CONCORD, CALIFORNIA - - The Contra Costa Mosquito & Vector Control District confirmed today that four more chickens have tested positive for West Nile virus this year in Contra Costa County. The chickens are located in an area east of Knightsen. 

"Our chicken program is one of the tools designed to find out where West Nile virus is," said Deborah Bass, public affairs manager for the District. "And that's exactly what it's done. However, we should assume that West Nile virus could be anywhere in the county. Wear repellent, empty the potted plant saucers, and make sure to maintain those swimming pools."

Chickens serve as sentinels for West Nile virus. The chickens, unlike other birds, do not get sick or die from the disease but develop antibodies that are detected in their blood. District vector ecologists sample the chickens' blood bi-weekly to determine if there is West Nile virus in a given area. Five flocks of chickens are maintained in Contra Costa County for this purpose.


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, 54 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 two groups of mosquitoes, one bird, and six chickens 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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