Trichonella spriralis

The parasite may be found in a wide variety of animals, including pigs, dogs, cats, rats, and many wild animals (such as fox, wolf, and polar bear). The disease is found only among those who eat pork, primarily in North America and Europe. Up to 5 percent of Americans have had an infestation, usually without symptoms. It is almost never a problem in countries such as France, where pigs eat root vegetables, not garbage.