Diphyllobothrium
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2008-07-13T12:51:26Z
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<!--Alright, three articles, three diferant bits of info. Tapeworm maximum length = 18 meters (Cestoda), 20 meters (Largest animels), or 30 meters (Fish tapeworm)???-->
{{Taxobox
| name = ''Diphyllobothrium''
| image = Diphyl proglottidE.JPG
| image_width = 200px
| image_caption = Proglottids of ''D. latum''
| regnum = [[Animal]]ia
| phylum = [[Platyhelminthes]]
| classis = [[Cestoda]]
| subclassis = [[Eucestoda]]
| ordo = [[Pseudophyllidea]]
| familia = [[Diphyllobothriidae]]
| genus = '''''Diphyllobothrium'''''
| subdivision_ranks = Species
| subdivision =
''D. latum''<br>
''D. pacificum''<br>
''D. cordatum''<br>
''D. ursi''<br>
''D. dendriticum''<br>
''D. lanceolatum''<br>
''D. dalliae''<br>
''D. yonagoensis''
}}
'''''Diphyllobothrium''''' is a genus of [[tapeworm]] best known for causing the infection [[Diphyllobothriosis]]. The principal species causing diphyllobothriosis is ''Diphyllobothrium latum'', known as the '''broad''' or '''fish tapeworm''', or '''broad fish tapeworm'''. ''D. latum'' is the longest [[tapeworm]] in humans, averaging ten meters long. Adults can shed up to a million eggs a day. ''D. latum'' is a [[pseudophyllid]] [[cestode]] that infects [[fish]] and [[mammals]]. It is [[morphology (biology)|morphologically]] very similar to other members of the genus ''Diphyllobothrium,'' but can sometimes be distinguished by host. Even this is not always possible, as there have been twelve other species of this genus reported to infect humans, especially ''[[Diphyllobothrium dendriticum]]'' (the '''salmon tapeworm'''), which has a much larger range (the whole northern hemisphere). ''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 Japan, the most common infecting species is ''D. nihonkaiense'', which was only identified as a separate species from ''D. latum'' in 1989.<ref>{{cite journal | title=A human infection of the cestode, ''Diphyllobothrium nihonkaiense'' | year=1989 | author=Lou YS, Koga M, Higo H, ''et al.'' | journal=Fukuoka Igaku Zasshi | volume=80 | pages=446–50 |pmid=2807129 }}</ref>
In adults, [[proglottid]]s are usually relatively wide (hence the name ''broad tapeworm''). As in all pseudophyllid cestodes, the [[genital pores]] open midventrally.
Several other ''Diphyllobothrium'' species have been reported to infect humans, but less frequently; they include '''''D. pacificum'', ''D. cordatum'', ''D. ursi'', ''D. lanceolatum'', ''D. dalliae'', and ''D. yonagoensis'''''.
==Life cycle==
[[Image:D latum LifeCycle.gif|thumb|left|280px|Life cycle of ''D. latum.'' Click the image to see full-size.]]
Adult tapeworms may infect humans, [[canid]]s, [[felidae|feline]]s, [[bear]]s, [[pinniped]]s, and [[mustelid]]s, though the accuracy of the records for some of the nonhuman species is disputed.
Immature eggs are passed in feces of the mammal host (the [[definitive host]], where the worms reproduce). After ingestion by a suitable freshwater [[crustacean]] such as a [[copepod]] (the first [[intermediate host]]) the coracidia develop into [[procercoid]] [[larva]]e. Following ingestion of the copepod by a suitable second intermediate host, typically a minnow or other small freshwater fish, the procercoid larvae are released from the crustacean and migrate into the fish's flesh where they develop into a [[plerocercoid]] larvae (sparganum). The plerocercoid larvae are the infective stage for the definitive host (including humans).
Because humans do not generally eat undercooked minnows and similar small freshwater fish, these do not represent an important source of infection. Nevertheless, these small second intermediate hosts can be eaten by larger predator species, for example, [[trout]], [[perch (fish)|perch]], and [[walleyed pike]]. In this case, the sparganum can migrate to the musculature of the larger predator fish and mammals can acquire the disease by eating these later intermediate infected host fish raw or undercooked. After ingestion of the infected fish, the plerocercoids develop into immature adults and then into mature adult tapeworms which will reside in the [[small intestine]]. The adults attach to the intestinal [[mucosa]] by means of the two bilateral grooves ([[bothria]]) of their scolex. The adults can reach more than 10 m (up to 30 m) in length in some species such as ''D. latum,'' with more than 3,000 proglottids. Immature eggs are discharged from the proglottids (up to 1,000,000 eggs per day per worm) and are passed in the feces. Eggs appear in the feces 5 to 6 weeks after infection. The tapeworm can live up to 20 years.
==References==
*{{cite web |url=http://www.dpd.cdc.gov/dpdx/HTML/Diphyllobothriasis.htm |title=DPDx - Diphyllobothriasis |format= |work=[[Centers for Disease Control and Prevention|CDC]] Division of Parasitic Diseases |accessdate=}}
*{{cite web |url=http://www.cfsan.fda.gov/~mow/chap26.html |title=UDiphyllobothrium spp. |format= |work=S FDA/CFSAN - Bad Bug Book |accessdate=}}
*{{cite book |author=Janovy, John; Roberts, Larry S. |title=Foundations of Parasitology |publisher=McGraw-Hill Education (ISE Editions) |location= |year=2005 |edition=7th ed. |pages= |isbn=0-07-111271-5 |oclc= |doi= |accessdate=}}
{{reflist}}
[[Category:Parasitic diseases]]
[[Category:Platyhelminthes]]
[[Category:Foodborne illnesses]]
[[de:Fischbandwurm]]
[[fr:Diphyllobothrium]]
[[id:Cacing pita ikan]]
[[nl:Vislintworm]]
[[pl:Bruzdogłowiec szeroki]]
[[fi:Lapamato]]
[[sv:Binnikemask]]