Two horses from Grant and Benton counties have tested positive for West Nile Virus, the Washington State Department of Agriculture (WSDA) confirmed on Monday.
Officials said the horses were not vaccinated or were under-vaccinated for the disease, and are recovering.
Last week, the Washington Animal Disease Diagnostic Laboratory at Washington State University reported the test results to WSDA.
"We have seen a decline in Washington state in recent years of this virus in horses, and we believe that is due to horse owners taking action before the season with vaccination. Any horse owner can request this vaccine from their veterinarian," said Washington State Veterinarian Dr. Amber Itle.
West Nile virus is spread by mosquitos that have fed on infected birds, and can sicken people, horses, birds and other animals but doesn't spread directly from horses to people or other animals. It's fatal to horses in about a third of the cases where clinical signs are apparent, according to the WSDA.
Itle recommends spring as the best time to vaccinate horses against the disease.
WSDA said veterinarians who discover potential West Nile virus cases in horses or other animals should contact the State Veterinarian’s Office at 360-902-1881.