Cases of West Nile virus in horses have been confirmed this summer in Lemhi, Blaine, Twin Falls, Canyon and Ada counties, according to the Idaho State Department of Agriculture.
One horse had to be euthanized, the department said.
The most common signs of West Nile virus in horses are fever and weakness, usually in the hindquarters, Idaho State Veterinarian Scott Leibsle said. Some horses stumble, lean to one side and drag their toes, he said. Affected horses also sometimes are fearful, smack their lips and their muscles tremor.
West Nile virus is most commonly spread to horses and humans through the bite of an infected mosquito. Leibsle said. Horses can be vaccinated against the virus, he said. The vaccine needs to be administered annually, a one-time vaccination is not enough, he said. People can also use fans or repellants to keep mosquitoes away from horses and standing water should be removed.
There is no vaccine against West Nile virus for people. State health officials say people can avoid the virus by using insect repellant, covering their skin when outside from dusk to dawn and keeping bugs outside homes with good house screens.