Lori Fox | Special to the News
The recent discovery of a strain of bacteria in southeast Alaska known to cause pneumonia in wild sheep is “of concern” to the Yukon, says the Yukon Fish and Game Association.
“This is an issue we have been concerned about for quite some time,” says Gordon Zealand, the executive director of the association.
The Alaska Department of Fish and Game announced March 13 that the bacteria — Mycoplasma ovipneumoniae, known as Movi for short — was detected during routine testing. The bacteria was found in four of 136 Dall’s sheep and two of 39 mountain goats tested, the department says. The sheep were harvested by hunters in a game management area south of Tok. The infected goats were found in the Kenai Peninsula, and were detected using live catch and release.
The bacteria “has been identified as a pathogen in Lower 48 bighorn sheep” and has resulted in “pneumonia outbreaks that have resulted in significant die-offs” in those populations, the department says.
“Pneumonia from Movi can develop as the result of multiple stressors including poor nutritional condition and/or environmental factors such as extreme weather, or high population density.”
Similar die-offs have been observed in British Columbia among bighorn sheep — to whom thinhorn sheep are closely related — from similar pathogens. No-die offs in thinhorn sheep have been recorded in the wild, although, as the News has previously reported, thinhorn sheep are generally believed by biologists to be susceptible to the disease.
“This bacteria has caused massive die-offs in other parts of North America,” says Zealand.
“It makes you even more worried. What is it going to take to cause a die-off (in the Yukon)?”
This is the first time Movi has been found in wild thinhorn sheep populations in Alaska, says Bruce Dale of the Alaska Department of Fish and Game.
Movi infects members of the sheep and goat family, both domestic and wild, as well as muskox, says Dale. In infected animals, the cilia — hair-like structures within the lungs that filter out dirt, bacteria and viruses — become paralyzed, which allows for dangerous secondary infections such as pneumonia, he says.
Dale says that, interestingly, all the sampled infected animals were, “alive and doing well,” including the animals brought in by hunters. None of the animals displayed symptoms of pneumonia.
Similar to the flu, there are potentially hundreds of strains of Movi bacteria, says Dale, which may explain why these animals are infected but asymptomatic.
Movi is extremely difficult to culture in the lab, he notes, because they are a simple bacteria, without a cell wall, which makes them exceptionally perishable.
The department is presently doing genetic testing on the strain isolated from the infected Alaskan animals in order to compare it to known disease-causing strains.
“Honestly, we don’t know what it means at this point,” says Dale.
“We don’t know if this is a different strain (than the southern one)…. The ability to spread disease is quite different from strain to strain.”
Healthy animals, Dale says, can be infected with the bacteria but not display symptoms. These animals can become carriers, spreading the bacteria to other animals over time, which may become sick. The bacteria is common in domestic sheep and goats, which usually harbour it without harm, although it can cause illness, especially in young animals.
Movi can easily be passed between wild and domestic animals through close contact and shared grazing areas. In recent years, this issue has created conflict between the owners of sheep and goats in the north, including farmers and homesteaders. Environmentalists and outfitters also fear similar die-off events as those seen in bighorn sheep.
Inversely, some farmers have said they don’t feel the government has studied the issue thoroughly enough and feel unfairly pressured to meet recommendations to prevent interactions. These recommendations include double fencing or adding electric fencing, a process which is expensive and labour-intensive.
“The Yukon Agricultural Association (YAA) takes this issue very seriously and is liaising with government agencies and wild sheep organizations to ensure that all stakeholders are part of a Yukon solution,” said Jennifer Hall, executive director of the YAA, in an email.
“(YAA) has been working hard to ensure that Yukon farmers have current information about testing procedures for domestic flocks as well as containment measures to prevent contact between wild and domestic sheep and goats.”
Hall said that local sheep and goat farmers were “very receptive” at a recent workshop to proposed Government of Yukon Animal Health Act regulation that would identify Movi as a “reportable hazard,” and lays out culling and compensation requirements.
In a statement, Environment Yukon says it’s aware of the Alaska outbreak, but says it has seen no evidence of any pneumonia outbreaks among wild thinhorn sheep in the Yukon. “It is difficult to quantify the risk of this occurring here, but due to geographic separation, risk is considered low,” the satement says. “We will continue to talk with our Alaskan counterparts about this finding and monitor the situation.”
The Yukon Outfitters Association did not reply to a request for comment by press time.
Some of the more concerned groups have tried to call for an outright ban on domestic sheep and goats in the Yukon.
Dale says there have been similar discussions in Alaska, and his department is working closely with the state’s own agricultural department regarding the matter. When it comes to the difficulties of balancing the needs and wants of domestic sheep and goat owners with wildlife concerns, Alaska is “actually in the same space as the Yukon right now,” he says.
Currently, wild sheep that come in contact with domestic sheep or goats are killed in the Yukon for the safety of the wild population. This was the case earlier last year in the Dawson City area, when a young wild ram was infamously photographed grazing with domestic sheep. That animal was captured and destroyed.
“The science remains inconclusive about risks of disease transfer from domestic to wild sheep and goats,” the Environment Yukon statement says. The department also says it is “exploring options for policy or regulatory solutions to mitigate the risk of disease transfer to the wild sheep population.”
The origin of this strain of Movi in the wild Alaskan sheep and goat populations is unknown at this time, says Dale.
Lori Fox is a former Yukon News reporter now based in Montreal.