BOISE — The Idaho State Department of Agriculture has confirmed equine herpes virus, known as EHV-1, at three different premises in Idaho.

The disease is highly contagious among horses but poses no threat to humans.

At two sites a more severe, neuropathogenic strain of the disease known as EHM that results in neurological symptoms, has been confirmed.

EHM was confirmed at one premise in Jerome County and one premise in Gooding County. Both are privately owned and under quarantine, said ISDA Chief of Operations Chanel Tewalt.

EHV-1 has been confirmed at a site in Gem County. That site is also under quarantine and the disease caused an abortion in a pregnant mare.

The strain of EHV-1 affecting the mare in Gem County is non-neuropathogenic and is known to commonly cause respiratory disease and abortions in mares, according to an ISDA news release.

An epidemiological investigation into the confirmed cases is ongoing but no link has been made among the three operations, Tewalt said.

There are different variants of EHV-1 and EHM is a neurological strain of the disease.

“Researchers have been unable to predict when a horse carrying EHV-1 will develop EHM,” Tewalt said. “But once a horse develops neurologic symptoms, they can be actively shedding virus which is a risk to other horses that come into contact with the (infected) horse.”

Vaccines are available for EHV, but they do not protect against the neurologic form of the disease, Tewalt said.

According to ISDA, EHV can be found in most horse populations around the world without causing clinical symptoms.

Symptoms of EHM in horses include fever, lethargy, in-coordination, weakness in the hindquarters, incontinence and diminished tail tone, according to the news release. It is easily spread through airborne transmission, horse-to-horse contact and contact with nasal secretions on tack, feed and other surfaces.

Although it’s not a threat to humans, people can spread the virus to horses through contaminated hands, clothing, shoes and vehicles.

“We encourage owners to contact their veterinarian immediately if they observe any symptoms of illness in their horses,” said Dr. Bill Barton, the state veterinarian.

People can report suspected or confirmed cases of EHM or EHV-1 by calling (208) 332-8540 or (208) 332-8570.

According to ISDA, biosecurity measures that horse owners can incorporate while transporting or boarding horses include disinfecting stalls before use, never sharing water, feed buckets, tack or groom equipment, and avoiding unnecessary contact with other horses.

People who work at more than one equine facility should wash their hands and change footwear and clothing before entering each facility, the news release said.

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