The West Nile virus has been blamed in the death of a Yakima woman, according to state health officials.
It is the first death attributable to the mosquito-spread disease in Washington this year.
There have been 31 other West Nile infections. Among those, 25 have suffered encephalitis, meningitis or paralysis. The others had mild illnesses with symptoms of fever and headache.
The Washington State Department of Health reported the virus was active this year in 15 counties, mostly in Eastern Washington.
The virus is a bird disease that can be spread to people who are bitten by a mosquito that became infected after feeding on a diseased bird.
There is no vaccine.