Bighorn sheep in Zion National Park have become infected with a disease called Sore Mouth Disease, or contagious ecthyma.
Sore Mouth Disease is a virus similar to chicken pox, and like chicken pox, it is typically a mild disease. People can be infected if direct contact with infected sheep occurs.
According to a Zion National Park news release, Sore Mouth Disease is a zoonotic disease, meaning it can spread from infected sheep to humans. People exposed to the virus, especially those with poor immune systems, can develop sores on their hands after touching the saliva or open sores of infected sheep. In humans, the sores are painful, but usually resolve on their own without treatment.
Aly Baltrus, a park spokesperson, said there have been no reported human cases in Zion National Park to date.
Jock Whitworth, Zion National Park superintendent, said reminding visitors not to approach or touch wildlife is the important part of this outbreak.
“People should never be approaching wildlife at Zion National Park, so we do not expect to have any issues with visitors contracting this disease from the bighorn sheep,” Whitworth said. “It is hard to watch a disease spread through a population, but we need to let nature take its course.”
Sore Mouth Disease is common throughout the world in wild and domestic sheep and goats. The disease spreads from ewes to lambs and can be seen as sores around the mouths of lambs and cause mastitis, inflammation of the ewes’ teats.
Sores typically disappear in two to four weeks. The disease is rarely fatal, but park biologists said they expect to see some mortality.
Baltrus said the mastitis is the greatest concern to the sheep affected by Sore Mouth Disease.
“Mortality rate should be relatively low,” Baltrus said. “This year’s lambs are the ones that are most susceptible, not directly from the disease, but because the disease causes a sore mouth for one to two weeks and because of that, the lambs may not want to suckle and fail to get enough nutrients from their mothers.”
Baltrus said the herd size of the Zion bighorn sheep is about 250, taken from an aerial survey a few years ago. Because of the size of the herd, Zion officials expect the disease to go through most of the herd.
“Since the incubation period of Sore Mouth Disease is one to two weeks, visitors could possibly see sick animals for many months as the disease moves through the population,” Baltrus said.There is no cure for Sore Mouth Disease in sheep; only supportive treatment can be given, Baltrus said. Treatment is not a viable option due to the number of animals involved and the stress it can put on the sick animals. Sore Mouth Disease will always exist, but subsequent outbreaks will be less severe.
If visitors inside the park do see a dead or dying bighorn sheep, please notify the park dispatch at 435-772-3256.