KING COUNTY, Wash. -- A woman in her 50s may be the first reported case of West Nile virus in the state, according to the Department of Health.

The virus was detected while the woman, who had not developed fever or any other complications, was being screened prior to donating blood.

The woman had traveled through Eastern Washington and Oregon during the period when she is believed to have contracted the virus, and officials say she likely contracted it in Eastern Washington.

Earlier this month the virus was found in two horses, one in Moses Lake and one in the Toppenish area. As recently as last Thursday mosquitos captured in the greater Yakima area tested positive for the virus.

Health officials remind the public that the best way to prevent contracting the virus is to avoid mosquito bites. They urge people, especially those over 50, to stay indoors during dawn and dusk, and to make sure screens on doors and windows are properly working. Residents should also get rid of any standing water around their homes.

More information on the disease is available at the Department of Health West Nile virus information line, (866)78-VIRUS, and on the agency's Web site.