PASCO, Wash. -

A Pasco-area horse with the West Nile virus has been euthanized.

KVEW reports the 10-year-old mare had not been vaccinated for the disease.

The state Department of Agriculture says it was the second case of the virus in a horse this year in Washington. The other confirmed case was last month in a horse pastured in Outlook, Yakima County.

Acting State Veterinarian Paul Kohrs says a killing frost will reduce the likelihood of further cases this year.

West Nile virus is spread by mosquitoes that have fed on infected birds.

The state Health Department says one person in Washington had the virus this year, but acquired it out of state.