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Cestoda
Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, commonly known as tapeworms. Their bodies consist of many similar units known as proglottids—essentially packages of eggs which are regularly shed into the environment to infect other organisms. Species of the other subclass, Cestodaria, are mainly fish-infecting parasites. All cestodes are parasitic; many have complex life histories, including a stage in a definitive (main) host in which the adults grow and reproduce, often for years, and one or two intermediate stages in which the larvae develop in other hosts. Typically the adults live in the digestive tracts of vertebrates, while the larvae often live in the bodies of other animals, either vertebrates or invertebrates. For example, '' Diphyllobothrium'' has at least two intermediate hosts, a crustacean and then one or mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proglottids
Cestoda is a Class (biology), class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, commonly known as tapeworms. Their bodies consist of many similar units known as proglottids—essentially packages of eggs which are regularly shed into the environment to infect other organisms. Species of the other subclass, Cestodaria, are mainly fish-infecting parasites. All cestodes are parasitism, parasitic; many have complex Life history theory, life histories, including a stage in a Host (biology)#Definitive and secondary hosts, definitive (main) host in which the adults grow and reproduce, often for years, and one or two intermediate stages in which the larvae develop in other hosts. Typically the adults live in the digestive tracts of vertebrates, while the larvae often live in the bodies of other animals, either vertebrates or invertebrates. For example, '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flatworm
Platyhelminthes (from the Greek language, Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") is a Phylum (biology), phylum of relatively simple bilaterian, Segmentation (biology), unsegmented, soft-bodied invertebrates commonly called flatworms or flat worms. Being acoelomates (having no coelom, body cavity), and having no specialised circulatory system, circulatory and respiratory system, respiratory organ (anatomy), organs, they are restricted to having flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion. The digestive cavity has only one opening for both ingestion (intake of nutrients) and egestion (removal of undigested wastes); as a result, the food can not be processed continuously. In traditional medicinal texts, Platyhelminthes are divided into Turbellaria, which are mostly non-parasitic animals such as planarians, and three entirely parasitic groups: Cestoda, Trematod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eucestoda
Eucestoda, commonly referred to as tapeworms, is the larger of the two subclasses of flatworms in the class Cestoda (the other subclass being Cestodaria). Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Cestodaria. All tapeworms are endoparasites of vertebrates, living in the digestive tract or related ducts. Examples are the pork tapeworm (''Taenia solium'') with a human definitive host, and pigs as the secondary host, and '' Moniezia expansa'', the definitive hosts of which are ruminants. Body structure Adult Eucestoda have a white-opaque dorso-ventrally flattened appearance, and are elongated, ranging in length from a few millimeters (about ¼") to 25 meters (80'). Almost all members, except members of the orders Caryophyllidea and Spathebothriidea, are polyzoic with repeated sets of reproductive organs down the body length, and almost all members, except members of the order Dioecocestidae, are protandral hermaphrodites. Most excep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cestodaria
Cestodaria is one of two subclasses of the class Cestoda Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, commonly known as tapeworms. Their bodies co .... The Cestodaria subclass is made up of Amphilinidea and Gyrocotylidea. The larvae have ten hooks on the posterior end.Rohde, K.The Amphilinidea, a small group of aberrant tapeworms. References Cestoda Protostome subclasses {{parasitic animal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echinococcus
''Echinococcus'' is a genus within Cestoda, a parasitic class of the platyhelminthes phylum (colloquially known as flatworms). Human echinococcosis is an infectious disease caused by the following species: '' E. granulosus'', '' E. multilocularis'', '' E. vogeli'' or '' E. oligarthrus''. ''Echinococcus'' is triploblastic – it has three layers – outermost ectoderm, middle mesoderm, and inner endoderm. An anus is absent, and it has no digestive system. Its body is covered by tegument and the worm is divided into a scolex, a short neck, and three to six proglottids. Its body shape is ribbon-like. In humans, ''Echinococcus'' spp. cause a disease called echinococcosis. The three types of echinococcosis are cystic echinococcosis caused by ''E. granulosus'', alveolar echinococcosis caused by ''E. multilocularis'', and polycystic echinococcosis caused by ''E. vogeli'' or ''E. oligarthrus''. A worm's incubation period is usually long and can be up to 50 years. Cystic echinococ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diphyllobothrium
''Diphyllobothrium'' is a genus of cestoda, tapeworms which can cause diphyllobothriasis in humans through consumption of wikt:raw, raw or undercooked fish. The principal species causing diphyllobothriasis is ''D. latum'', known as the broad or fish tapeworm, or broad fish tapeworm. ''D. latum'' is a pseudophyllid cestode that infects fish and mammals. ''D. latum'' is native to Scandinavia, western Russia, and the Baltics, though it is now also present in North America, especially the Pacific Northwest. In Far East Russia, ''D. klebanovskii'', having Pacific salmon as its second intermediate host, was identified. Other members of the genus ''Diphyllobothrium'' include ''Diphyllobothrium dendriticum, D. dendriticum'' (the salmon tapeworm), which has a much larger range (the whole northern hemisphere), ''D. pacificum'', ''D. cordatum'', ''D. ursi'', ''D. lanceolatum'', ''D. dalliae'', and ''D. yonagoensis'', all of which infect humans onl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taenia Solium
''Taenia solium'', the pork tapeworm, belongs to the cyclophyllid cestode family Taeniidae. It is found throughout the world and is most common in countries where pork is eaten. It is a tapeworm that uses humans (''Homo sapiens'') as its definitive host and pigs and boars (family Suidae) as the Host (biology)#Types of hosts, intermediate or secondary hosts. It is transmitted to pigs through human feces that contain the parasite eggs and contaminate their fodder. Pigs ingest the morula, eggs, which develop into larvae, then into oncospheres, and ultimately into infective tapeworm cysts, called cysticerci. Humans acquire the cysts through consumption of uncooked or under-cooked pork and the cysts grow into adult worms in the small intestine. There are two forms of human infection. One is "primary hosting", called taeniasis, and is due to eating under-cooked pork that contains the cysts, resulting in adult worms in the intestines. This form generally is asymptomatic, without symptom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hymenolepis (flatworm)
''Hymenolepis'' is a genus of cyclophyllid tapeworms that cause hymenolepiasis. They parasitise mammals, including humans. Some notable species are: * '' Hymenolepis apodemi'' - in rodents * '' Hymenolepis asymetrica'' — in rodents * '' Hymenolepis diminuta'' — in humans * '' Hymenolepis horrida'' — in rodents * '' Hymenolepis rymzhanovi'' — in rodents * '' Hymenolepis microstoma'' — in rodents * '' Hymenolepis nana'' — in humans * '' Hymenolepis tualatinensis'' — in rodents Disease Signs and symptoms Most infected humans have a low number of worms and therefore are asymptomatic. Patients with more than 15,000 eggs per gram of stool may experience cramps, diarrhea, irritability, anorexia, or enteritis caused by cystercoids destroying the intestinal villi in which they develop. Diagnosis Diagnosis for hymenolepiasis is done by examining stool for eggs. The proglottids that are disintegrated in the intestine cannot be detected. Egg output can be sporadic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetragonoporus
''Tetragonoporus'' is a genus of cestodes in the order Pseudophyllidea. It is a monotypic genus, and the only species is ''Tetragonoporus calyptocephalus'', previously known as ''Polygonoporus giganticus''. This tapeworm is a gut parasite of whales. Description The adult ''T. calyptocephalus'' is found in the gut of whales such as the sperm whale. It is normally present in the intestine, but can also occur in the bile duct. The tapeworm can be almost in length with as many as 45,000 proglottids (segments). The scolex (head) of the tapeworm is attached to the lining of the gut and the proglottids continuously develop from behind the scolex. As more segments are produced, the older ones become larger and more mature. In this species, the scolex is short and equipped with two suckers, and the proglottids develop in groups of three different sizes – small, medium and large – which are repeated throughout the length of the strobila (segmented body). The cuticle is thin and ther ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taenia Saginata
''Taenia saginata'' (synonym ''Taeniarhynchus saginatus''), commonly known as the beef tapeworm, is a zoonotic tapeworm belonging to the order Cyclophyllidea and genus ''Taenia''. It is an intestinal parasite in humans causing taeniasis (a type of helminthiasis) and cysticercosis in cattle. Cattle are the intermediate hosts, where larval development occurs, while humans are definitive hosts harbouring the adult worms. It is found globally and most prevalently where cattle are raised and beef is consumed. It is relatively common in Africa, Europe, Southeast Asia, South Asia, and Latin America. Humans are generally infected as a result of eating raw or undercooked beef which contains the infective larvae, called cysticerci. As hermaphrodites, each body segment called proglottid has complete sets of both male and female reproductive systems. Thus, reproduction is by self-fertilisation. From humans, embryonated eggs, called oncospheres, are released with faeces and are transmitted to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tegument (helminth)
Tegument is a term in helminthology for the outer body covering of members of the phylum Platyhelminthes. The name is derived from a Latin word ''tegumentum'' or ''tegere'', meaning "to cover". It is characteristic of flatworms including the broad groups of tapeworms and flukes. Once considered to be a non-living component, it is now known to be a dynamic cellular structure. In fact it is a living structure consisting of proteins, lipids, carbohydrates and RNA. It forms the protective layer and the host-parasite interface of the worms, serving both secretory and absorptive functions.Cheng TC (1986). ''General Parasitology, 2nd edn''. Academic Press, Division of Hardcourt Brace & Company, USA, pp. 253-2546. Structure and composition The fine structure of tegument is essentially the same in both the cestodes and trematodes. A typical tegument is 7-16 μm thick, with distinct layers. It is a syncytium consisting of multinucleated tissues with no distinct cell boundaries. The oute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Larva
A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase of their life cycle. A larva's appearance is generally very different from the adult form (''e.g.'' caterpillars and butterflies) including different unique structures and organs that do not occur in the adult form. Their diet may also be considerably different. In the case of smaller primitive arachnids, the larval stage differs by having three instead of four pairs of legs. Larvae are frequently adapted to different environments than adults. For example, some larvae such as tadpoles live almost exclusively in aquatic environments but can live outside water as adult frogs. By living in a distinct environment, larvae may be given shelter from predators and reduce competition for resources with the adult population. Animals in the lar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
