A dead crow found on the front lawn of an Arcadia home earlier this month has tested positive for the West Nile virus, suggesting that the disease has made its way to Los Angeles County, officials said Monday.
But county health authorities said they had no reports of the virus in humans or mosquitoes. It has also not been found in the local flocks of chickens whose blood is regularly tested for the presence of West Nile as an early warning system.
Los Angeles County is the third county in the state to report positive test results for West Nile. Earlier this month, Riverside County authorities said they had detected the virus in a chicken flock near the city of Mecca in the Coachella Valley. In August, Imperial County reported finding West Nile in mosquitoes and chicken flocks.
Officials with the San Gabriel Valley Mosquito and Vector Control District in Los Angeles County said they had picked up the dead bird on Sept. 3 and sent it for testing to the state lab at UC Davis. The test results came back positive Monday morning and were released publicly.
The presence of the virus locally comes as no surprise to health authorities, who have been watching it migrate westward for the last four years.
West Nile is harbored by birds, including crows and ravens, and transmitted to humans by mosquitoes.
A Los Angeles County woman was diagnosed with West Nile last year, but the source of her illness was never determined. As a result of the infection, the woman was hospitalized for viral meningitis, in which the membranes covering the brain become irritated. She recovered fully. Other cases in the state last year occurred in residents infected outside California.
Thirty-seven states have reported the illness this year, according to the U.S. Centers for Disease Control and Prevention.
Anyone who finds a dead bird is asked to call the county health department within 48 hours at toll-free (877) 747-2243.