Contra Costa Mosquito & Vector Control

FOR IMMEDIATE RELEASE     -     September 12, 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


More mosquitoes and birds test positive for virus


CONCORD, CALIFORNIA - - Simple dump and drain activities by the public to eliminate and discourage mosquitoes in their own yards can result in a big payoff: reduced risk of contracting West Nile virus according to the Contra Costa Mosquito & Vector Control District. 


"West Nile virus infections are largely preventable, even though mosquitoes can thrive in just a couple of tablespoons of water," said Deborah Bass, spokesperson for the District. "One of the biggest sources of mosquitoes is residential yards. Creating a habit to dump and drain any standing water on a regular basis makes a huge difference towards reducing mosquito production and risk of virus. Look for mosquito sources when you take a walk in your yard with your Sunday morning coffee or when you take out the garbage. It's all about the habit."

The District reports today that a group of mosquitoes from Brentwood tested positive for West Nile virus as well as two birds, one from San Ramon and one from Orinda. This is the first time that West Nile virus has been detected in Orinda this year.  All 2014 West Nile virus activity can be found on the District's website.

"This year is very different from other years," Bass said. "The amount of mosquitoes is not very high, but the ones that are there have a high rate of infection. That tends to happen in drought years and we're seeing it throughout California now."

According to the California West Nile Virus website, so far this year there are 238 human cases compared to 117 last year, 1891 dead birds compared to 1022 last year, and 2660 mosquito samples compared to 2048 last year. In fact, state health officials reported last week that the number of infected mosquitoes statewide is at an all time high, and so prevention is key. Infected mosquitoes can infect people with the virus in just a single bite.


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, 48 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 20 groups of mosquitoes, 13 chickens and 37 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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