From Big Medical Encyclopedia

BIOHELMINTHS (Greek bios life + helminth[s]) — helminths for whose completion of development change of owners is necessary.

The group B. includes flat and roundworms, including trematodes (see. Trematodoza ), cestodes (see. Tsestodoza ) and a nematode (see. Nematodoses ). An organism, B.'s larvae develop in Krom, is called the intermediate owner. In an organism of the final (definitivny) owner B. reaches puberty. Intermediate owners are specific to separate groups B., e.g.: for trematodes — mollusks, for cestodes — Copepoda crustaceans, and also the person and vegetarians, for a number of nematodes — blood-sicking insects. The person is a final owner for all trematodes, the majority of cestodes and for a number of nematodes.

The typical representative B. is a bull tapeworm. Its adult form parasitizes in a human body, larvae — at cattle. Sometimes the additional owner is necessary for full development of a larva of B. With change of three owners the wide tape-worm, an opistorchis develops, etc.

B. causes diseases, many of which are dangerous to the person and animals: fastsioleza (see), Opisthorchosis (see), paragonimiasis (see), Echinococcosis (see), teniidoza (see), trichinosis (see) and others helminthoses (see). In view of danger of the diseases caused by B. with them the systematic fight based on the solution of the main task — to break off a chain of development B is conducted. In this regard knowledge of ontogenesis of B. is of great importance.

On the relation of early stages of B. to the environment and the mechanism of infection of the person distinguish the following groups B.: 1) the helminthoses which are not connected with the environment; infection occurs through the products containing larvae of parasites — at the use by the person in food of the meat struck with Finns (a bull tapeworm); 2) the helminthoses which are closely connected with the environment; the person catches from dogs, hoofed animals — eating the grass contaminated by excrements of dogs (echinococcus); 3) the helminthoses caused by B. which larvae are capable to develop in the soil (a dwarfish tapeworm).

See also Helminths , Hozyain of a parasite .

Bibliography: The multivolume guide to microbiology, clinic and epidemiology of infectious diseases, under the editorship of H. N. Zhukova-Verezhnikov, t. 9, page 347, M., 1968.

Yu. K. Bogoyavlensky.