The woman in her 50s was hospitalized. Another travel-related case has also been confirmed — a teenage boy who lives in Clark County.
Test results were confirmed at the Washington State Public Health Laboratories in Shoreline, bringing the total 2012 West Nile virus case count in Washington to four. Nationally, 48 states have reported human West Nile virus infections this year.
In Washington, tests have also confirmed the virus in five mosquito samples so far this year, all from the south central part of the state.
A horse in Benton County was diagnosed with West Nile virus infection in August and was euthanized.
West Nile virus is primarily a bird disease, and often dead birds are an early sign that the disease is active in an area.
People may report dead birds online. No dead birds have been reported with the infection so far this year in the state. The virus is spread when mosquitoes feed on infected birds then bite people, horses, and other mammals.