West Nile virus has been found in a mosquito sample taken from the Winchester Wasteway near Ephrata, officials said Tuesday.
The sample was taken in conjunction with monitoring efforts by state and county officials and Grant County Mosquito Control District No. 1.
The positive sample indicates that the virus is present in Grant County, health officials said.
Monitoring for West Nile virus has been underway in Washington for the past several weeks to track the spread of the potentially deadly virus.
Last year, Washington reported one death among 38 human infections from the virus, which is transmitted by mosquitoes.
In Idaho last year, another 38 cases of human infection were reported, leading to two deaths.
Also on Tuesday, the Idaho Department of Health and Welfare issued a precaution that wet weather and local flooding has set the stage for mosquito populations to be larger than normal.
In 2006, also a wet year, Idaho had more than 1,000 cases of the virus and 23 deaths, officials said. That outbreak subsided in subsequent years.
Health officials are cautioning people to protect themselves by avoiding the outdoors between dusk and dawn, wearing mosquito repellent and protective clothing and dumping out standing water in gutters, bird baths, buckets or tires.
“Avoiding mosquito bites is the key to preventing infection,” said Gregg Grunenfelder, Washington’s assistant health secretary.
Health departments in Washington are asking residents to report freshly dead crows, jays, magpies and raptors. Monitoring of dead birds is part of the effort to track the virus. Those types of birds spread the virus to mosquitoes, which in turn bite humans.
In Spokane, dead birds should be reported to the health district at 324-1560, extension 7.
One in about five people bitten by an infected mosquito will develop symptoms, which are like a influenza and may also include a skin rash and swollen lymph nodes in the neck.
A serious case leads to neck stiffness, disorientation, coma, tremors, vision loss, numbness, paralysis, convulsions and muscle weakness.