The Washington State Department of Agriculture (WSDA) has confirmed five new cases of West Nile virus (WNV) in horses, bringing to six the number of cases so far this year and now surpassing the total number in the state for all of 2014.

The first case of West Nile virus in a horse this year was reported July 21 and involved an unvaccinated Quarter horse gelding in Kennewick. The horse’s condition continues to improve.

Veterinarians reported five new cases since then, all confirmed as positive for WNV by the Washington Animal Disease Diagnostic Laboratory operated by Washington State University in Pullman. They include:

  • A 2-year-old unvaccinated Andalusian stud colt from Harrah, Yakima County. The horse’s condition is improving.
  • A 4-year-old unvaccinated Andalusian stud in Kennewick, Benton County. He has been euthanized.
  • A 3-year-old unvaccinated Quarter Horse gelding in Mesa, Franklin County. The horse died.
  • A 9-year-old Appaloosa mare in Othello, Adams County. It is unclear if this horse was vaccinated, but she appears to be recovering.
  • A 3-year old Azteca male in Mabton, Yakima County. The horse was not vaccinated and appears to be recovering.

Washington had five confirmed cases of horses with West Nile virus last year, with the first case reported Aug. 19, 2014. The affected horses were in Benton, Franklin, Grant, Okanogan, and Yakima counties.

West Nile virus is spread to horses by mosquitoes that have fed on infected birds. The disease sickens people, horses, birds and other animals, but it does not spread directly from horses to people or other animal