A second case of equine West Nile virus in Washington has resulted in the death of a 10-year-old mare from north Pasco.
Department of Health officials said the horse, which was not vaccinated for the disease, was euthanized.
West Nile is potentially fatal in infected equines, other mammals and birds. The Washington State University’s Animal Disease Diagnostic Laboratory in Pullman reported the positive test results to the State Veterinarian’s Office earlier this week.
The only other confirmed case of West Nile virus in a Washington horse this year was reported in late September for a horse pastured in Outlook, Yakima County.
The virus is spread by mosquitoes that have fed on infected birds. The disease sickens people, horses, birds and other animals but does not spread from horses to people or other animals.
According to the Centers for Disease Control and Prevention, 1,135 human cases have been reported nationwide this year.
“A killing frost will reduce the likelihood of further cases for the year,” said Paul Kohrs, acting state veterinarian. “Horse owners in areas of the state where this disease will overwinter should consider vaccinating for West Nile in 2014 at least a month before the onset of the mosquito season.”