A small, slender nematoid worm (Trichina spiralis) which,
   in the larval state, is parasitic, often in immense numbers, in the
   voluntary muscles of man, the hog, and many other animals. When
   insufficiently cooked meat containing the larvae is swallowed by man,
   they are liberated and rapidly become adult, pair, and the
   ovoviviparous females produce in a short time large numbers of young
   which find their way into the muscles, either directly, or indirectly
   by means of the blood. Their presence in the muscles and the intestines
   in large numbers produces trichinosis.