Horses are exercised at the Eldorado Polo Club during a state-imposed quarantine of the area after a horse at Empire Polo Club tested positive for the equine herpes virus and had to be euthanized. Omar Ornelas/The Desert Sun
Professional polo player Alvaro Tadeo takes the body temperature of one of his horses at the Eldorado Polo Club to determine if there is any indication of fever. Eldorado and Empire polo clubs are under a quarantine after after a horse tested positive for equine herpes. Omar Ornelas/The Desert Sun
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Indio — Cases of the sometimes deadly equine herpes virus have increased over the past decade, but have not reached epidemic levels, according to animal health experts.
Still, local horse owners and polo players say they are fearful of this emerging virus that has shown up and shut down matches at Indio's Empire Polo Club.
A horse stabled there was euthanized Monday after testing positive for the neurological form of the virus.
As a result, Empire and neighboring Eldorado Polo Club horses are now under a 21-day quarantine.
Polo games and practices have been postponed or cancelled until the quarantine is lifted.
Other parts of the state have also been affected.
Since Jan. 11, 16 horses have tested positive for the virus at Rancho Sierra Vista in San Juan Capistrano.
And in September, eight horses in Tuolumne County and three horses in Sonoma County tested positive for the disease.
Dr. Kent Fowler, animal health branch chief and veterinarian for the California Department of Food and Agriculture said Friday that there is no evidence at this time of a link between any of the incidents.
That was not the case in May, when infected horses at the National Cutting Horse Association Western National Championship in Ogden, Utah spread the disease to 12 other states, said Fowler.
“There was transmission as those horses left Utah and went to other shows,” he said.
The equine herpes virus manifests in two forms — one causes pregnant mares to abort, while the other causes a respiratory infection and neurological problems.
Experts say it's the neurological strain that has increased globally over the past decade.
“There does seem to be more cases reported over the last 10 years than the 30 years prior to that. We think a lot of that is better diagnosis ... of this viral disease,” said Fowler.
Dr. Gregory Ferraro, director for the Center of Equine Health at UC Davis, compared the equine herpes virus to the human herpes simplex 1 virus, which affects about 85 percent of people.
Almost all horses older than 2 years old have been exposed to the equine virus, but it remains in a dormant state with no signs of illness.
Then for some reason, possibly stress, the virus is activated, he said.
“We don't really understand transmission, infection, why some horses get sick. Herpes virus are strange,” he said.
Vicky Owens, polo manager at Empire Polo Club, said she was unfamiliar with this disease until now.
“It's new to us we've never had it happen. We're taking temperatures twice a day making sure there's no sick horses. We're doing everything we can. We're hoping for 21 total days of clear,” she said.
The quarantine affects the areas bordered by Avenues 50 and 52 and Madison and Monroe streets and was initiated by the state Department of Food and Agriculture.
No horses are allowed in or out of the area.
The horses in the Forum field stables, which is where the infected horse was kept, are under lockdown.
Horses elsewhere within the quarantined area are being compartmentalized and their handlers are being asked to keep them within their zones.
The virus is most commonly transmitted by horses nose to nose, said Fowler, but can also be spread through contaminated tack and equipment.
“People that get the virus on their hands and clothes and go from an infected horse to a non-infected horse,” said Fowler.
Officials say the equine virus will not manifest in humans.
But for horses, it causes symptoms such as fever, nasal discharge, a lack of voluntary muscle movement, hind-end weakness and lethargy.
People in the quarantined area are being asked to use bleach to disinfect all equipment that each horse has been in contact with.
Animal health officials said horse owners should be vigilant, but not panic.
“They should be concerned from the standpoint that it can be a disease that can be fatal. Most often it is not. But they should practice proper biosecurity measures,” he said.
Xochitl Peña covers Indio and Coachella for The Desert Sun. She can be reached at (760) 778-4647 or xochitl.pena@thedesertsun.com.
