Contra Costa Mosquito & Vector Control

FOR IMMEDIATE RELEASE     -     October 13, 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


People most likely infected in August/September


CONCORD, CALIFORNIA - - The Contra Costa Mosquito & Vector Control District received reports of three more people testing positive for West Nile virus and is reporting another dead bird and mosquito sample as well. 


"These people were most likely infected in August or September, with symptoms presenting themselves usually three to 14 days later. That, combined with doctor's visits, a thorough investigation including travel history, testing and notification to the various agencies takes time and is why cases are announced at a later date," said Steve Schutz, Ph.D., scientific program manager for the District. "Our District is notified by the local health department of locations where human infections may have occurred and we respond immediately, even before travel history is known, to conduct thorough surveillance and control, if needed, in those areas."

The District works collaboratively with the health department due to the nature of vectors -- animals or insects that transmit disease or cause discomfort to people. All questions concerning human cases should be directed to the state or local health department.

Other West Nile virus activity continues in Contra Costa County. The District reports today that another group of mosquitoes from an agricultural area east of Discovery Bay tested positive for West Nile virus as well as one dead bird from Alamo. All 2014 West Nile virus vector activity can be found on the District's website. 

According to the California West Nile Virus website, so far this year compared to the same time last year there are 488 human cases compared to 236 last year, 2275 dead birds compared to 1168 last year, 3139 mosquito samples compared to 2440 last year, and 382 chickens compared to 425 last year . 


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 2014, a total of five people, 23 groups of mosquitoes, 14 chickens and 43 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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