SAN RAMON, Calif. -- A dead crow found in San Ramon has tested positive for the West Nile virus, the third bird in the county to test positive for the mosquito-borne disease this year, Contra Costa Mosquito and Vector Control District officials said Wednesday.
The dead American crow was found on Monday near the intersection of Norris Canyon and Bollinger Canyon roads, according to district spokeswoman Deborah Bass.
Two dead birds carrying the West Nile virus were previously found in Alamo and Pleasant Hill in April and May. The crow discovered on Monday is the first bird found in San Ramon to test positive for the virus since 2012, Bass said.
"We should all assume that West Nile virus is active everywhere in the county," she said. "Take the appropriate precautions. It only takes one mosquito bite from an infected mosquito to get the disease."
Bass said birds are "the reservoir" for the disease, which is spread by mosquitoes. That means mosquitoes that feed on infected birds can then bite people, she said.
Some 47 people have been diagnosed with the virus in Contra Costa County since 2005. In 2006, two people in the county died from the disease, Bass said.
In 2012, the last year for which there are records, 212 people in Contra Costa County reported being infected with the virus, according to district officials.
Symptoms of West Nile virus can include fever, diarrhea, rash, swollen lymph glands, tiredness and head and body aches, although many people infected show no symptoms.
The best line of defense for residents against West Nile virus is to eliminate mosquito magnets by dumping standing water. People can also protect themselves by avoiding being outside when mosquitoes are around, usually at dawn or dusk, and by wearing mosquito repellant while outdoors, Bass said.
The public is encouraged to report dead birds, which can then be tested for the virus, to the state West Nile virus hotline at (877) 968-2473 or at www.westnile.ca.gov.
Neglected swimming pools, a major source of virus-carrying mosquitoes, can be reported by calling (925) 771-6195.