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trichina (trĭkīˈnə), common name for species of roundworm of the phylum Nematoda. The species Trichinella spiralis is an important parasite, occurring in rats, pigs, and man, and is responsible for the disease trichinosis. The small adult worms mature in the intestine of an intermediate host such as a pig. Each adult female produces batches of up to 1,500 live larvae, which bore through the intestinal wall, enter the blood and lymphatic system, and are carried to striated muscle tissue. Once in the muscle, they encyst, or become enclosed in a capsule. Larvae encysted in the muscles remain viable for some time. When the muscle tissue is eaten by a human, the cysts are digested in the stomach; the released larvae migrate to the intestine to begin a new life cycle. Female trichina worms live about six weeks and in that time may release 15,000 larvae. The migration and encystment of larvae can cause fever, pain, and even death. Encysted larvae in pork are destroyed by thorough cooking or long periods of low-temperature storage. Trichina are classified in the phylum Nematoda.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



(Trichinella spiralis), a parasitic roundworm of the family Trichinellidae. Adult males measure 1.2–1.6 mm in length, and females measure as much as 4.5 mm. The worms usually live in the intestines of predatory or omnivorous mammals and human beings; they cause trichinosis. Fertilized females penetrate the intestinal wall of the host and hatch tiny viable larvae measuring 0.09–0.1 mm in length and 0.006 mm in width. The larvae are carried by lymph and blood through the host’s body and migrate from the capillaries to striated muscles. There they grow and after two or three weeks become encysted as a result of the protective reaction of the host, remaining viable for a year or more. To continue their development, trichinae must reach the intestine of another mammal.This happens when the flesh of an infested animal is consumed. A human being may become infected by eating pork or the insufficiently roasted or boiled meat of other animals. Encysted larvae develop into adult worms in the intestine.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.