Polar Bear Perils

When you’re hungry, a polar bear steak or a pork chop may seem appealing. But buried deep within the meat – in the skeletal muscle of the animal – may exist tiny larvae of the nematode Trichinella spiralis, a parasite of mammals, particularly carnivores. Inspection of the meat will not reveal the presence of the nematode, but cooking the meat will kill it. The dangers of eating raw or undercooked meat that contains this worm can be severe, and the lack of cooking fuel in the Arctic heightens the risk.
     
The larvae of this minute worm live in the muscle tissue, within rice grain-shaped cysts made of calcium. Here, they wait until a carnivore ingests them. Only then do the larvae develop into adults in the intestinal walls of their consumer. From this vantage point, the adult nematodes reproduce, releasing larvae which migrate through the bloodstream into the muscle.
     
Ingesting Trichinella can result in the painful disease, trichinosis. In the Arctic, polar bear meat is the source of most cases, because of the high incidence of infection in this species, as well as the high concentration of larvae in the meat – in one study, the average gram of meat contained 4 larvae! The severity of trichinosis symptoms depends on the number of larvae that are swallowed, but at its worst can include violent abdominal pain, headache, fever, diarrhea, and collapse. In an extreme case, trichinosis killed an important polar explorer and zoologist, Bernhard Hantzsch, in 1911. “I’m more dead than alive” he wrote in his journal two days before his death at the age of 36, less than one month after consuming several meals of polar bear. Besides humans and polar bears, walrus, dogs, wolves, and foxes are commonly infected.