The Contra Costa Mosquito & Vector Control District confirmed Tuesday that dead American crows found in San Ramon, Antioch and Brentwood tested positive for West Nile virus.
In addition, a group of mosquitoes and a chicken tested positive for the virus in Holland Tract near Brentwood. This is the first group of mosquitoes and chicken that tested positive this year in Contra Costa County.
"This is not surprising given the amount of West Nile virus activity in our neighboring counties right now," said Deborah Bass, district public affairs manager. "West Nile virus is extremely active and our message is -- take precautions against mosquito bites seriously."
The two species of mosquitoes in the county capable of transmitting the virus prefer to feed on birds -- the reservoir for West Nile. However, people can become infected when a mosquito bites an infected bird and then bites a person.
West Nile virus symptoms include a mild fever, headache, body aches, fatigue, and swollen lymph glands. The illness can last a few days, but people have reported being sick for several weeks. A severe form of the virus can be fatal.
Residents can reduce their risk of contracting mosquito-borne diseases by following these guidelines offered by district officials:
Dump or drain standing water. Mosquitoes can't begin their lives without water.
Defend oneself 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 771-6195 or online. 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, 45 people in Contra Costa County have been diagnosed with West Nile virus and two people have died from the virus.