The Contra Costa Mosquito & Vector Control District said Thursday that six dead birds tested positive for West Nile virus. Two birds were found in Brentwood and one each in Antioch, Bethel Island, Oakley and Martinez, according to the district.

"The steady stream of dead birds positive for West Nile virus and the high virus activity surrounding Contra Costa County clearly illustrates that we all need to heed the districts' warnings," Steve Schutz, scientific program manager for the district, said in a statement Thursday.

The San Joaquin County Public Health Services revealed in a statement Tuesday that the person who died from the virus, the county's first fatality since 2007, was an 83-year-old Stockton woman. Her identity was not released.

Despite the number of birds that have tested positive for the virus recently, district spokeswoman Deborah Bass said there are no plans to spray anytime soon.

The numbers don't warrant spraying right now, Bass said. "Every year is different, and we have had a pretty cool summer so far, and that has worked in our favor."

Factors that are used to determine whether the district sprays include weather, number of mosquitoes tested positive for the virus and whether or not the virus is detected near where people live.

Symptoms of West Nile virus can include a mild fever, headache, fatigue, body aches and swollen lymph glands; if left untreated, the disease can prove fatal. While the illness can last only a few days, some patients remain sick for several weeks, according to the district.


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To reduce the risk of infection, the district recommends residents dump or drain standing water, use repellents containing DEET, picaridin, or oil of lemon eucalyptus and avoid being outdoors when mosquitoes are present, typically dawn and dusk.

Since 2005, 42 people in Contra Costa County have been diagnosed with West Nile virus. In 2006, two people died from the disease.

So far in 2013, a total of four groups of mosquitoes and 37 dead birds have tested positive for the virus, the district stated in a news release.

Bass said those numbers are low compared with neighboring counties, like Sacramento, where 222 groups of mosquitoes have tested positive for the virus.

Visit the district's website at www.contracostamosquito.com for current West Nile virus activity or to receive automatic emails for when the district fogs for adult mosquitoes.

Follow Katie Nelson at Twitter.com/katienelson210.