tapeworm

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tapeworm

 [tāp´werm]
any parasitic worm of the subclass Cestoda; these have a flattened bandlike form and numerous species can lodge in the intestines of many animals including human beings. Tapeworms are transmitted to humans in larval form embedded in cysts, in meat or fish that is not properly cooked. In the human body they develop to maturity and attach themselves to the wall of the intestine, where they grow and release eggs. Called also cestode.



Although a large variety of adult tapeworms are sometimes human parasites, only a few infect humans to any great degree. Taenia saginata, the beef tapeworm, and T. solium, the pork tapeworm, are widespread and quite common. Beef tapeworms grow to a length of 4 to 8 meters (12 to 25 feet), and adult pork tapeworms average 2 to 4 meters (6 to 12 feet) in length. Both species release white, egg-containing proglottids, or segments of the body, which make their way to the anus and may be found in clothes or bedding. Diphyllobothrium latum, the fish tapeworm, is found in North America in the Great Lakes region, as well as in Northern Europe and Japan; it may grow as long as 18 meters (60 feet). Hymenolepis nana and H. diminuta are dwarf tapeworms that are common in the tropics and subtropics.

The diagnosis of a tapeworm infection is made when segments of the worm are found in clothing or bedding or when characteristic eggs or segments are found in the stool. Occasionally diarrhea, vague abdominal cramps, flatulence, distention, and nausea occur. Mental deterioration and seizures are rare complications, occurring only when larval forms of the worm invade brain tissue. Tapeworm infection can be prevented by cooking pork, beef, and fish properly. Although most meats and fish are inspected under government supervision, eggs and larvae are not always detectable; the only certain protection is proper cooking.

Once it is inside the body, the tapeworm can be eliminated by specific anthelmintic drugs or surgery. The drug of choice is usually praziquantel, which should be given in a dose large enough to cause the worm to release its hold and pass out through the intestinal tract. If the head is found in the evacuated feces, no further treatment is necessary. However, if the head is not found, the worm could regenerate in two to three months, with segments reappearing in the stools.

Echinococcus granulosus and E. multilocularis differ from other tapeworms in that the adults infect animal hosts and the larval forms are found in humans. The larvae develop in the human intestine, penetrate its wall, and are carried by the lymphatics to various organs of the body where they form slowly growing cysts (hydatid cysts). The liver is the organ most commonly involved. Treatment is by surgical removal of the cyst. Infection with this worm (echinococcosis or hydatid disease) is uncommon in the United States.
Tapeworm: Life cycle of Taenia spp. From Mahon and Manuselis, 2000.
armed tapeworm Taenia solium.
beef tapeworm Taenia saginata.
broad tapeworm Diphyllobothrium latum.
dog tapeworm Dipylidium caninum.
fish tapeworm Diphyllobothrium latum.
hydatid tapeworm Echinococcus granulosus.
pork tapeworm Taenia solium.
unarmed tapeworm Taenia saginata.

tape·worm

(tāp'wŏrm),
An intestinal parasitic worm, adults of which are found in the intestine of vertebrates; the term is commonly restricted to members of the class Cestoidea. Tapeworms consist of a scolex, variously equipped with spined or sucking structures by which the worm is attached to the intestinal wall of the host, and strobila having several to many proglottids that lack a digestive tract at any stage of development. The ovum, entering the intestine of an appropriate intermediate host, hatches and the hexacanth penetrates the gut wall and develops into a specific larval form (for example, cysticercoid, cysticercus, hydatid, strobilocercus), which develops into an adult when the intermediate host is ingested by the proper final host. A three-host cycle with a swimming coracidium, procercoid and plerocercoid (sparganum) larva, and adult intestinal worm is found in aquatic life cycles, as in Diphyllobothrium latum (broad fish tapeworm) and other pseudophyllid cestodes. Other important species of tapeworm are Echinococcus granulosus (hydatid tapeworm), Hymenolepis nana or H. nana var. fraterna (dwarf or dwarf mouse tapeworm), Taenia saginata (beef, hookless, or unarmed tapeworm), T. solium (armed, pork, or solitary tapeworm), and Thysanosoma actinoides (fringed tapeworm of sheep).

tapeworm

/tape·worm/ (tāp´werm) cestode; a parasitic intestinal worm with a flattened, bandlike form.
armed tapeworm  Taenia solium.
beef tapeworm  Taenia saginata.
broad tapeworm  Diphyllobothrium latum.
dog tapeworm  Dipylidium caninum.
fish tapeworm  Diphyllobothrium latum.
hydatid tapeworm  Echinococcus granulosus.
pork tapeworm  Taenia solium.
unarmed tapeworm  Taenia saginata.

tapeworm

(tāp′wûrm′)
n.
Any of various long segmented parasitic flatworms of the class Cestoda that lack a digestive system and have hooks or suckers for attaching to the intestines of vertebrates, including humans. Also called cestode.

tapeworm

[tāp′wurm]
Etymology: AS, taeppe + wyrm
a parasitic intestinal worm belonging to the class Cestoda and having a scolex and a ribbon-shaped body composed of segments in a chain. Tapeworms live as larvae in one or more vertebrate intermediate hosts and grow to adulthood in the intestine of humans. In the human alimentary canal the worm develops into an adult with an attaching head, or scolex, and numerous hermaphroditic segments, or proglottids, each of which is capable of producing eggs. Kinds of tapeworm include Diphyllobothrium latum, Taenia saginata, and Taenia solium. Also called cestode.

tape·worm

(tāp'wŏrm)
An intestinal parasitic worm, adults of which are found in the intestine of vertebrates. Tapeworms consist of a scolex, variously equipped with spined or sucking structures by which the worm is attached to the intestinal wall of the host, and strobila having several to many proglottids that lack a digestive tract at any stage of development. The ovum, entering the intestine of an appropriate intermediate host, hatches, and the hexacanth penetrates the gut wall and develops into a specific larval form (e.g., cysticercoid, cysticercus, hydatid, strobilocercus), which develops into an adult when the intermediate host is ingested by the proper final host.

tapeworm

A ribbon-like population, or colony, of joined flatworms, of the class Cestoda , derived from a common head (scolex) equipped with hooks or suckers by which it is attached to the lining of the intestine. Each segment, of which there may be a thousand, is called a proglottid and each contains both male and female reproductive organs. The younger, smaller proglottids release sperms which fertilize the eggs in the older, larger, proglottids. Fertilized segments break off and are passed in the faeces. If these are eaten by an animal (the intermediate host), the larvae develop, travel to the animal's muscles and form cysts, and if such animal meat is eaten, undercooked, the worm is released in the intestine, attaches itself, and the life cycle is continued. Tapeworms can be eliminated with anthelmintic drugs.

tapeworm

any parasitic flatworm of the class Cestoda (phylum Platyhelminthes). The adults attach themselves inside the gut system of vertebrates by means of hooks and suckers on the SCOLEX, and the long, ribbonlike body made up of a series of proglottides,may reach a length in excess of 10 m in some species. Eggs develop into 6-hooked embryos and pass out with the FAECES of the host, and if eaten by a suitable secondary host, develop into a larval stage called a CYSTICERCUS. When eaten by the primary host, (which may take place in some species only after transfer through a second secondary host) the tapeworm becomes sexually mature.

Tapeworm

Flat and very long (up to 30 meters) intestinal parasitic worms, similar to a long piece of tape. Common tapeworms include: T. saginata (beef tapeworm), T. solium (pork tapeworm) D. latum (fish tapeworm), H. Nana (dwarf tapeworm) and E. granulosus (dog tapeworm). General symptoms are vague abdominal discomfort, nausea, vomiting, diarrhea and weight loss.

tapeworm

members of the genera Taenia, Diphyllobothrium, Dipylidium and Echinococcus; includes infestation with members of the tapeworm class Eucestoda. Most tapeworm infestations have little apparent effect on the health of farm livestock and are mostly esthetic problems in companion animals.

armed tapeworm
taeniasolium.
beef tapeworm
taeniasaginata.
broad tapeworm
dog tapeworm
dipylidiumcaninum.
fish tapeworm
hydatid tapeworm
echinococcusgranulosus.
pork tapeworm
taeniasolium.
unarmed tapeworm
taeniasaginata.
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