tapeworm

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of various ribbonlike, often very long flatworms of the class Cestoda, that lack an alimentary canal and are parasitic in the intestines of vertebrates, including humans.

Century Dictionary and Cyclopedia

1. n. An entozoic parasitic worm, of flattened or tape-like form and indeterminate length, consisting of many separable joints, found in the adult state in the alimentary canal of most vertebrated animals. Such worms belong to the order Cestoidea or Tæniada, family Tæniidæ, and several different genera, especially Tænia, the true tapeworms, and Bothriocephalus, the broad tapes. The so-called “head” of a tapeworm, small and inconspicuous in comparison with the great length to which the body may attain, is the whole of the real worm, all the rest of the joints being merely successive generative buds, which contain the matured sexual elements, and are technically called proglottides. They are continually budded off from the head, the oldest joint being the one furthest from the head; and any number of them may be broken off and expelled from the body withont stopping their continual gemmation. This is why no tapeworm can be eradicated nnless the head is expelled from the host. The chain of links or joints is the strobila; it may consist of several hundred generative buds, and grow to be several yards long. These formidable parasites are parenchymatous, having no mouth nor alimentary canal, and live by absorbing nourishment from that intended to nourish the host, so that persons thus parasitized may suffer from defective nutrition while acquiring a ravenous appetite. The head of the tape is provided with hooks or suckers, or both, for adhering to the mucous membrane of the host. The ova, matured in every one of the joints, do not complete their development in the animal in which the adult exists. They require to be swallowed by some other vertebrate, the ripe proglottides being expelled from the bowel of the host with all their contained ova fertilized. The segments or proglottides decompose and liberate the ova, which are covered with a capsule. After being swallowed the capsule bursts, and an embryo, called a proscolex, is liberated. This embryo, by means of spines, perforates the tissues of some contiguous organ, or of a blood-vessel. in the latter case being carried by the blood to some solid part of the body, as the liver or brain, where it surrounds itself with a cyst, and develops a vesicle containing a fluid. It is now called a scolex or hydatid, and was formerly known as the cystic worm. The scolex is incapable of further development till swallowed and received a second time into the alimentary canal of a vertebrate. Here it becomes the head of the true tapeworm (see tænia-head), from which proglottides are developed posteriorly by gemmation, and the adult animal with which the cycle began is thus reached. (See cut under tænia.) At least eight tapeworms, mostly of the genus Tænia, are found in man. The pork tape is T. solium, which in its cystic form (the socalled Cysticercus cellulosæ) in the pig produces the disease measles (see measles, 2); it is acquired by those who eat measly pork, or raw sausages made with such pork. The beef-tape is T. mediocanellata. The Egyptian or dwarf tape is T. nana; others are the elliptic-jointed, T. elliptica; the crested, T. lophosoma; the spotted, T. flavopuncta. A dogtape is T. serrata; its larva, called Cysticercus pisiformis, is the pea-measle of the rabbit. Another dog-tape is T. cœnurus, whose larva is the cystic worm (Cœnurus cerebralis) of the sheep's brain, producing the gid or staggers. A third dog-tape is T. echinococcus, whose larva, known as Echinococcus veterinorum, is a common hydatid sometimes found in man. T. marginata of the dog is the tapeworm from the slender hydatid Cysticercus tenuicollis of the sheep. A cysticercus of the mouse becomes Tænia crassicollis in the cat. Certain cysticerci of moles become in the fox Tænia tenuicollis and T. crassiceps. The broad tapeworm of man is Bothriocephalus latus, also called Swiss tapeworm, and another human parasite of this genus is B. cordatus. Tapes are also called ribbon-worms. See cut under Cestoidea, also cœnurus, cysticercus, echinococcus, hydatis, proglottis, scolex, deutoscolex, strobila.

Wiktionary

1. n. Any parasitical worm of the class Cestoda, which infest the intestines of both animals and humans.
2. n. A broad fish tapeworm, Diphyllobothrium latum.

GNU Webster's 1913

1. n. (Zoöl.) Any one of numerous species of cestode worms belonging to Tænia and many allied genera. The body is long, flat, and composed of numerous segments or proglottids varying in shape, those toward the end of the body being much larger and longer than the anterior ones, and containing the fully developed sexual organs. The head is small, destitute of a mouth, but furnished with two or more suckers (which vary greatly in shape in different genera), and sometimes, also, with hooks for adhesion to the walls of the intestines of the animals in which they are parasitic. The larvæ (see cysticercus) live in the flesh of various creatures, and when swallowed by another animal of the right species develop into the mature tapeworm in its intestine. See Illustration in Appendix.

WordNet 3.0

1. n. ribbonlike flatworms that are parasitic in the intestines of humans and other vertebrates