A bacterium threatens musk oxen | Polarjournal
Musk oxen prefer low precipitation tundra as their habitat. They are mainly found in lower-lying plains and river valleys. If they fail to build up a sufficient fat reserve for the winter due to poor grazing and weather conditions, they are threatened with starvation, usually in late winter and at the beginning of spring. (Photo: Walter Notter)

Musk oxen, shaggy-haired Arctic survivors of the Pleistocene, have faced many challenges since the end of the last ice age. Now there is another: a bacterium that is more common in southern farm animals such as pigs and chickens. Evidence of the bacterium “Erysipelothrix rhusiopathiae” was found after increased deaths of musk oxen after extensive testing. This was reported by the magazine PLOS ONE in a study.

Area of investigation and origin of samples from 818 musk oxen tested for “Erysipelothrix rhusiopathiae”. For each region, the number of seropositives/number of muskoxen tested and the percentage of positives is given. A: Nunivak-Island; B: Game Management Unit (GMU) 22; C: GMU 23; D: GMU 26; E: Banks Island; F: Victoria-Island; G: Kitikmeot mainland.

“Erysipelothrix rhusiopathiae” causes infections that are usually fatal for animals. The bacterium is blamed for the recent death of musk oxen on Banks Island and Victoria Island in the Canadian Northwest Territories. Areas hosting large but declining populations of musk oxen. The bacterium-related death occurred in summer and has been described as sudden and unrelated to food shortages.

When information about summer deaths arrived, scientists from Canada and Alaska joined forces to try to understand the extent of infection in musk oxen.

“When the bacterium appeared on Banks Island and Victoria Islands, it was a pretty big deal,” said Layne Adams, a biologist with the U.S. Geological Survey and co-author of the new study. While working in northwestern Alaska, she also came across a summer death of musk oxen.

Today, musk oxen live in larger numbers in Greenland, Canada, Siberia and Alaska and as smaller herds in Norway and Sweden. However, only their occurrence in northern Canada and northeastern Greenland is of natural origin. (Photo: Walter Notter)

The newly published study analyzed 818 blood samples taken from musk oxen in Alaska and Canada. More than a quarter of them tested positive for the bacterium. According to the study, the bacterium has been detectable in musk ox populations for a long time. However, there are indications that the infection rate among muskoxen is increasing.

“In some populations the disease seems to have increased with the bacterium,” said Fabien Mavrot, a Swiss veterinarian from the University of Calgary and lead author of the study. “But there are gaps in the information, so general conclusions are premature. We can’t say with certainty that this is a general trend for every musk ox population we’ve tested,” he said.

“The bacterium ‘Erysipelothrix rhusiopathiae’ is very well able to jump from one species to another,” continued Mavrot. In musk oxen, “Erysipelothrix rhusiopathiae” contributes to a number of stress factors for the animals, which in combination can make them vulnerable.

Although the bacterium is known to infect farm animals, it has also been found in wild animals such as deer, wolves and foxes. It can be transmitted by fish, marine mammals and birds. In the far north, caribou and musk oxen walking across sea ice may carry the bacterium from island to island.

In humans, infections are considered an occupational risk for veterinarians, farm workers, hunters and other people who work with animals. The usual result of an infection is a skin rash that can easily be treated with antibiotics.

Heiner Kubny, PolarJournal

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