Трихинелла: Паразитті құрттар туысы

Genus of worms

Trichinella is the genus of parasitic roundworms of the phylum Nematoda that cause trichinosis (also known as trichinellosis). Members of this genus are often called trichinella or trichina worms. A characteristic of Nematoda is the one way digestive tract, with a pseudocoelom (body cavity made up of only an ectoderm and endoderm). The genus was first recognised in a larval form in 1835. The L1 larvae live in a modified skeletal muscle cell. The adult worms occupy a membrane bound portion of columnar epithelium, living as intramulticellular parasites of animals, including humans. Infections with this genus have been reported from more than 150 different naturally or experimentally infected hosts. It has been shown to have a worldwide distribution in domestic and/or sylvatic animals. Trichinella is the smallest human nematode parasite, yet it is also the largest of all intracellular parasites. Oral ingestion of cyst or larvae contaminated tissue is the usual route of infection, but congenital and mammary transmission can occur in rats.

Eight species are currently recognized. Four additional genotypes require adequate description before they can be recognized as valid species. Two main clades are recognized in the genus: one group (T. britovi, T. murrelli, T. nativa, T. nelsoni, T. spiralis) that encapsulates in host muscle tissue and a second (T. papuae, T. pseudospiralis, T. zimbabwensis) that does not. The nonencapsulated group infects saurians, crocodilians, and other nonavian archosaurs (T. papuae, T. zimbabwensis) and birds (T. pseudospiralis). The encapsulated group infects synapsid and mammalian hosts. T. spiralis and T. nelsoni appear to be basal in the encapsulated group and T. murrelli and T. nativa the most recently evolved.

Artificial digestion is used to detect the presence of encysted trichinella larvae in suspected muscle tissue. The meat sample is dissolved by a digestive solution and the remains are examined for the presence of larvae.

Treatment is by either thiabendazole or mebendazole.

Trichinella infection can be prevented by cooking pork meat properly, or by freezing pork. However, freezing pork is not an effective method for killing larvae. One way to prevent trichinellosis is to cook meat to a safe temperature (at least internal temperature as measured by a food thermometer, followed by a three minute rest for fresh pork). The meat is not safe until cooking is completed. To help prevent Trichinella infection in animal populations, pigs or wild animals should be prevented from eating uncooked meat, scraps, or carcasses of any animals, including rats, which may be infected with Trichinella, in order to break the oral ingestion cycle of infection.