The Washington state Department of Health has been notified by Grant County that a mosquito sample taken June 16 near Moses Lake has tested positive for West Nile virus.
This is the first confirmed environmental sample of West Nile virus in a mosquito pool in Washington this year, officials said.
It comes at the end of an extended spring that, while staying cool, has produced an abundance of rain, said Harvey Crowder, administrator for Walla Walla County Public Health Department.
With the rain comes more standing water and with that comes more mosquito-breeding habitat, he said Tuesday.
The weather is bound to change into a true summer at any moment, thus supplying the insects with all the components needed for multiplying, he noted. "That increases the chances of disease.
The virus can be a serious, even fatal, illness and can affect people, horses, some birds and other animals.
The virus first appeared in the United States in New York City in 1999. Since that time, it has spread rapidly throughout the country.
In Washington, the first cases of people becoming ill from West Nile virus were reported in 2006.
The virus is almost always spread to people by the bite of an infected mosquito. Mosquitoes become infected after feeding on birds that carry the virus. There is no evidence that West Nile virus can be spread by direct contact with infected people or animals.
Most people who are infected with the disease will not get sick. One to five of those infected will have mild symptoms such as fever, headache and body aches. About one in 150 people infected will have more severe symptoms, which can include headache, high fever, neck stiffness, stupor, disorientation, tremors, convulsions, muscle weakness, paralysis, and coma.
For more information, go to doh.wa.gov/ehp/ts/Zoo/WNV/WNV.html