TRICHINA, tri-ki'nft (Neo-T.at., from Ok. thrix, hair). A peculiar nematode worm, which, in its sexually immature state, inhabits the muscles of mammals, usually the pig. It was discovered in 1835.
The young triehinte, as they are seen in human muscle, present the form of spirally coiled worms, in the interior of small, globular, oval, or lemon shaped cysts, which appear as minute specks scarcely visible to the naked eye. The cysts are sometimes altogether absent, and hence they mutt be regarded as formations resulting from local in flammation set up by the presence of the worm, which in this larval condition of existence meas ures about a millimeter long. These larval worms exhibit a well-marked digestive apparatus, and afford evidence of the presence of reproductive organs, which are often sufficiently developed to enable the observer to determine the sex. The number of larval triehime that may simultane ously exist in the museles of a single man or animal is enormous.
When an animal is fed with tleAb containing the larval worm and is killed a few days after wards, a large number of minute worms are found mixed with the contents of the small in testines. On the second day after their intro duction these intestinal triebinre attain their full sexual maturity, and in six days the females contain perfectly developed and free embryos in their interior.
The female is a slender round worm, varying in length I- of an inch. The anterior end presents a bead-like appearance, from which the intestinal canal proceeds. The posterior three-fourths are mainly occupied by the repro ductive organ, which is filled partly with free embryos, and partly with eggs in various stages of maturity. The females continue bringing
forth young for a period of two or three weeks. The embryos penetrate the walls of the intestine, and pass either through the body cavity or by means of the blood-vessels into the muscles of the host, where, if the conditions are otherwise favorable, they are developed into the eneysted form. Some of them reach the muscles of the extremities and other distant parts; hut the ma jority remain in those sheathed muscular groups which are nearest to the cavity of the hotly (abdomen and thorax). especially in those which are smaller and most supplied with connective tissue. These embryos penetrate into the interior of the separate muscle fibres, and in the course of fourteen day's acquire the size and organiza tion of Trichina. spiralis. In the adult condition triehinte perish in cold water in about an hour, and cannot survive the decease of their host for more than six hours, but the larvae remain alive in water for a month, and will live for a long time in flesh which has become putrid. in this wiry a carcass near a marsh or rivulet may com municate the parasites to the ruminants that drink the water, or to pigs. The formation of the cysts is the cause of more or less serious injury to the host, according to the number pres• eat. When abundant, the weakness is very marked and is often fatal. In man in feet ion oc curs, almost invariably through the eating of raw or underdone pork containing the cysts. If the meat is properly cooked the worms will be destroyed. Consult Braun, Die tierischen Para sitcn des Menschen 1902). Sec PARASITE, ANIMAL.