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Trichina
(redirected from trichinas)

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trichina (trĭkī`nə), common name for species of roundworm of the phylum Nematoda Nematoda , phylum consisting of about 12,000 known species, and many more predicted species of worms (commonly known as roundworms or threadworms). Nematodes live in the soil and other terrestrial habitats as well as in freshwater and marine environments.
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. The species Trichinella spiralis is an important parasite, occurring in rats, pigs, and man, and is responsible for the disease trichinosis trichinosis or trichiniasis , parasitic disease caused by the roundworm Trichinella spiralis. It follows the eating of raw or inadequately cooked meat, especially pork.
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. 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.

trichina

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Trichina encysted in muscle
(credit: Russ Kinne-Photo Researchers/EB Inc.)
Species (Trichinella spiralis) of parasitic nematode, found worldwide, that causes the disease trichinosis. Trichinae (or trichinas), 0.06–0.2 in. (1.5–4 mm) long, mate in the host's small intestine. Fertilized females penetrate the intestinal wall and release larvae, which the blood carries throughout the body. The larvae grow, mature, and become encysted within muscle tissue. The digestive juices of an animal that eats the muscle tissue break down the cyst, liberating the larvae for further development; the worms mature, and the cycle begins again.


Trichina 

(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.



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