Diphyllobothrium: Difference between revisions

From Wikipedia, the free encyclopedia
Browse history interactively
← Previous edit
Content deleted Content added
VisualWikitext
Citation bot (talk | contribs)
Bots
4,934,740 edits
m Alter: journal, isbn. Add: date. Removed parameters. | You can use this bot yourself. Report bugs here. | NessieVL
→‎Disease: Changed "must also undergo" to "should be offered" for the sake of appropriate respect for medical autonomy.
 
(44 intermediate revisions by 33 users not shown)
Line 1: Line 1:
{{Short description|Genus of flatworms}}
{{Italic title}}
{{Automatic taxobox
{{Taxobox
⚫
| name = ''Diphyllobothrium''
| image = Diphyl proglottidE.JPG
| image = Diphyl proglottidE.JPG
| image_width = 200px
| image_caption = Proglottids of ''D. latum''
| image_caption = Proglottids of ''D. latum''
⚫
| taxon = Diphyllobothrium
| regnum = [[Animal]]ia
| authority = [[Thomas Spencer Cobbold|Cobbold]], 1858
| phylum = [[Platyhelminthes]]
| classis = [[Cestoda]]
| subclassis = [[Eucestoda]]
| ordo = [[Pseudophyllidea]]
| familia = [[Diphyllobothriidae]]
⚫
| genus = '''''Diphyllobothrium'''''
| genus_authority = Cobbold, 1858
| subdivision_ranks = Species
| subdivision_ranks = Species
| subdivision =
| subdivision =
⚫
* ''[[Diphyllobothrium cordatum]]''
''D. latum''<br>
* ''[[Diphyllobothrium dendriticum]]''
''D. pacificum''<br>
''D. cordatum''<br>
* ''[[Diphyllobothrium elegans]]''
* ''[[Diphyllobothrium elegans]]''
* ''[[Diphyllobothrium lanceolatum]]''
* ''Diphyllobothrium latum'' [[Carl Linnaeus|Linnaeus]], 1757
''D. ursi''<br>
''D. dendriticum''<br>
''D. lanceolatum''<br>
''D. dalliae''<br>
''D. yonagoensis''<br>
''D. nihonkaiense''=''D. klebanovskii''
| synonyms = ''Cordicephalus'' Wardle, McLeod & Stewart, 1947
| synonyms = ''Cordicephalus'' Wardle, McLeod & Stewart, 1947
}}
}}

<!--Alright, three articles, three different bits of info. Tapeworm maximum length = 18 meters (Cestoda), 20 meters (Largest animals), or 30 meters (Fish tapeworm)???-->
'''''Diphyllobothrium''''' is a genus of [[cestoda|tapeworm]]s which can cause [[diphyllobothriasis]] in humans through consumption of [[wikt:raw|raw]] or undercooked fish. The principal [[species]] causing diphyllobothriasis is ''Diphyllobothrium 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.<ref name=Muratov1>{{cite journal | last1 = Muratov | first1 = IV | last2 = Posokhov | first2 = PS | title = Causative agent of human diphyllobothriasis--Diphyllobothrium klebanovskii sp. n. | journal = Parazitologiia | volume = 22 | issue = 2 | pages = 165–70 | year = 1988 | pmid = 3387122 }}</ref>
'''''Diphyllobothrium''''' is a genus of [[cestoda|tapeworm]]s 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.<ref name=Muratov1>{{cite journal | last1 = Muratov | first1 = IV | last2 = Posokhov | first2 = PS | title = Causative agent of human diphyllobothriasis--Diphyllobothrium klebanovskii sp. n. | journal = Parazitologiia | volume = 22 | issue = 2 | pages = 165–70 | year = 1988 | pmid = 3387122 }}</ref>

Other members of the genus ''Diphyllobothrium'' include ''[[Diphyllobothrium 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 only infrequently. In Japan, the most common species in human infection is ''D. nihonkaiense'', which was only identified as a separate species from ''D. latum'' in 1986.<ref name=Yamane>{{cite journal | last1 = Yamane | first1 = Y | last2 = Kamo | first2 = H | last3 = Bylund | first3 = G | last4 = Wikgren | first4 = BJ | year = 1986 | title = ''Diphyllobothrium nihonkaiense'' sp. nov (Cestoda: Diphyllobothriidae)---revised identification of Japanese broad tapeworm | url = | journal = Shimane J Med Sci | volume = 10 | issue = | pages = 29–48 }}</ref> More recently, a molecular study found ''D. nihonkaiense'' and ''D. klebanovskii'' to be a single species.<ref name=Arizono>{{cite journal | last1 = Arizono | first1 = N | last2 = Shedko | first2 = M | last3 = Yamada | first3 = M | last4 = Uchikawa | first4 = R | last5 = Tegoshi | first5 = T | last6 = Takeda | first6 = K | last7 = Hashimoto | first7 = K | title = Mitochondrial DNA divergence in populations of the tapeworm ''Diphyllobothrium nihonkaiense'' and its phylogenetic relationship with ''Diphyllobothrium klebanovskii'' | journal = Parasitology International | volume = 58 | issue = 1 | pages = 22–8 | year = 2009 | pmid = 18835460 | doi=10.1016/j.parint.2008.09.001 }}</ref>
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 only infrequently. In Japan, the most common species in human infection is ''D. nihonkaiense'', which was only identified as a separate species from ''D. latum'' in 1986.<ref name="Yamane">{{cite journal | last1 = Yamane | first1 = Y | last2 = Kamo | first2 = H | last3 = Bylund | first3 = G | last4 = Wikgren | first4 = BJ | year = 1986 | title = ''Diphyllobothrium nihonkaiense'' sp. nov (Cestoda: Diphyllobothriidae)---revised identification of Japanese broad tapeworm | journal = Shimane J Med Sci | volume = 10 | pages = 29–48 }}</ref> More recently, a molecular study found ''D. nihonkaiense'' and ''D. klebanovskii'' to be a single species.<ref name="Arizono">{{cite journal | last1 = Arizono | first1 = N | last2 = Shedko | first2 = M | last3 = Yamada | first3 = M | last4 = Uchikawa | first4 = R | last5 = Tegoshi | first5 = T | last6 = Takeda | first6 = K | last7 = Hashimoto | first7 = K | title = Mitochondrial DNA divergence in populations of the tapeworm ''Diphyllobothrium nihonkaiense'' and its phylogenetic relationship with ''Diphyllobothrium klebanovskii'' | journal = Parasitology International | volume = 58 | issue = 1 | pages = 22–8 | year = 2009 | pmid = 18835460 | doi=10.1016/j.parint.2008.09.001 }}</ref>
<!--ref>{{cite journal | title=A human infection of the cestode, ''Diphyllobothrium nihonkaiense'' | year=1989 |vauthors=Lou YS, Koga M, Higo H, etal | journal=Fukuoka Igaku Zasshi | volume=80 | pages=446–50 |pmid=2807129 | issue=9 }}</ref-->
<!--ref>{{cite journal | title=A human infection of the cestode, ''Diphyllobothrium nihonkaiense'' | year=1989 |vauthors=Lou YS, Koga M, Higo H, etal | journal=Fukuoka Igaku Zasshi | volume=80 | pages=446–50 |pmid=2807129 | issue=9 }}</ref-->


==History==
==Morphology==
[[File:Diphyllobothrium latum scolex x40.png|thumb|''Diphyllobothrium latum'' scolex]]
[[File:Diphyllobothrium latum scolex x40.png|thumb|''Diphyllobothrium latum'' scolex]]
The fish tapeworm has a long documented history of infecting people who regularly consume fish and especially those whose customs include the consumption of raw or undercooked fish. In the 1970s, most of the known cases of diphyllobothriasis came from Europe (5 million cases), and Asia (4 million cases) with fewer cases coming from North America and South America, and no reliable data on cases from Africa or Australia.<ref name=scholz>{{cite journal | title=Update on the Human Broad Tapeworm (Genus Diphyllobothrium), Including Clinical Relevance | year=2009 | author=Scholz, T| journal=Clinical Microbiology Reviews| volume=22 | pages=146–160 |pmid=19136438 | doi=10.1128/CMR.00033-08 | issue=1 | pmc=2620636|display-authors=etal}}</ref> Despite the relatively small number of cases seen today in South America, some of the earliest archeological evidence of diphyllobothriasis comes from sites in South America. Evidence of ''Diphyllobothrium spp.'' has been found in 4,000- to 10,000-year-old human remains on the western coast of South America.<ref>{{cite journal | title=Parasitology as an interpretive tool in archaeology | year=1992 | author=Reinhard, KJ | journal=American Antiquity | volume=57 | pages=231–245 |pmid= | doi=10.2307/280729 | jstor=280729 | issue=2 | url=http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1032&context=natresreinhard }}</ref> There is no clear point in time when ''Diphyllobothrium latum'' and related species were “discovered” in humans, but it is clear that diphyllobothriasis has been endemic in human populations for a very long time. Due to the changing dietary habits in many parts of the world, autochthonous, or locally acquired, cases of diphyllobothriasis have recently been documented in previously non-endemic areas, such as Brazil.<ref>Llaguno, Mauricio M., et al. “''Diphyllobothrium latum'' infection in a non-endemic country: case report.” (2008) Revista da Sociedade Brasileira de Medicina Tropical, 41 (3), 301-303</ref> In this way, diphyllobothriasis represents an emerging infectious disease in certain parts of the world where cultural practices involving eating raw or undercooked fish are being introduced.


⚫
The adult worm is composed of three fairly distinct morphological segments: the scolex (head), the neck, and the lower body. Each side of the scolex has a slit-like groove, which is a [[bothrium]] for attachment to the intestine. The scolex attaches to the neck, or proliferative region. From the neck grow many proglottid segments which contain the reproductive organs of the worm. ''D. latum'' is the longest [[tapeworm]] in humans, averaging ten meters long. Unlike many other tapeworms, ''Diphyllobothrium'' eggs are typically unembryonated when passed in human feces.<ref>{{cite book |last1=Ash |first1=Lawrence |last2=Orihel |first2=Thomas |title=Ash & Orihel's Atlas of Human Parasitology |date=2007 |publisher=American Society for Clinical Pathology Press |edition=5th}}</ref>
==Morphology==


In adults, [[proglottid]]s are wider than they are long (hence the name ''broad tapeworm''). As in all pseudophyllid cestodes, the [[genital pores]] open midventrally.<ref>{{cite journal |last1=Poddubnaya |first1=Larisa G |last2=Mackiewicz |first2=John S |last3=Brunanská |first3=Magdaléna |last4=Scholtz |first4=Tomás |title=Fine structure of the female reproductive ducts of Cyathocephalus truncatus (Cestoda: Spathebothriidea), from salmonid fish |journal=Folia Parasitologica |date=November 2005 |volume=52 |issue=4 |pages=323–338 |doi=10.14411/fp.2005.045|pmid=16405296 |doi-access=free }}</ref>
⚫
The adult worm is composed of three fairly distinct morphological segments: the scolex (head), the neck, and the lower body. Each side of the scolex has a slit-like groove, which is a [[bothrium]] for attachment to the intestine. The scolex attaches to the neck, or proliferative region. From the neck grow many proglottid segments which contain the reproductive organs of the worm. ''D. latum'' is the longest [[tapeworm]] in humans, averaging ten meters long. Adults can shed up to a million eggs a day.

In adults, [[proglottid]]s are wider than they are long (hence the name ''broad tapeworm''). As in all pseudophyllid cestodes, the [[genital pores]] open midventrally.


==Life cycle==
==Life cycle==

[[Image:D_latum_LifeCycle.png|thumb|left|280px|Life cycle of ''D. latum.'' Click the image to see full-size.]]
[[Image:D_latum_LifeCycle.png|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]], [[walleye]], and [[Esox|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 ([[bothrium|bothria]]) of their scolex. The adults can reach more than 10 m (up to 30&nbsp;ft) in length in some species such as ''D. latum,'' with more than 3,000 proglottids. One or several of the tape-like proglottid segments (hence the name tape-worm) regularly detach from the main body of the worm and release immature eggs in fresh water to start the cycle over again. Immature eggs are discharged from the proglottids (up to 1,000,000 eggs per day per worm) and are passed in the feces. The incubation period in humans, after which eggs begin to appear in the feces is typically 4–6 weeks, but can vary from as short as 2 weeks to as long as 2 years.<ref name="web.gideononline.com">http://web.gideononline.com/web/epidemiology/</ref> The tapeworm can live up to 20 years.

==Clinical symptoms, including occasional parasite-induced B<sub>12</sub> deficiency==
Symptoms of diphyllobothriasis are generally mild, and can include diarrhea, abdominal pain, vomiting, weight loss, fatigue, constipation and discomfort.<ref>{{cite web|url=http://www.dpd.cdc.gov/dpdx/HTML/diphyllobothriasis.htm |title=DPDx - Diphyllobothriasis |publisher=Dpd.cdc.gov |date= |accessdate=2012-12-30}}</ref> Approximately four out of five cases are asymptomatic and may go many years without being detected.<ref name=scholz/> In a small number of cases, this leads to severe [[Vitamin B12|vitamin B<sub>12</sub>]] deficiency due to the parasite absorbing 80% or more of the host’s B<sub>12</sub> intake, and a [[megaloblastic anemia]] indistinguishable from [[pernicious anemia]].<ref>John, David T. and Petri, William A. (2006)</ref> The anemia can also lead to subtle demyelinative neurological symptoms ([[subacute combined degeneration of spinal cord]]). Infection for many years is ordinarily required to deplete the human body of vitamin B-12 to the point that neurological symptoms appear.

==Diagnosis==
[[File:Diphyllobothrium latum proglottid.png|thumb|''Diphyllobothrium latum'' proglottid]]
[[File:Diphyllobothrium latum proglottid.png|thumb|''Diphyllobothrium latum'' proglottid]]
[[File:Diphyllobothrium latum egg.jpg|thumb|''Diphyllobothrium latum'' – fertilized egg]]
Diagnosis is usually made by identifying proglottid segments, or characteristic eggs in the feces.<ref name="web.gideononline.com"/> These simple diagnostic techniques are able to identify the nature of the infection to the genus level, which is usually sufficient in a clinical setting.<ref name=scholz/> However, when the species needs to be determined (in epidemiological studies, for example), restriction fragment length polymorphisms can be effectively used. [[Polymerase Chain Reaction|PCR]] can be performed on samples of purified eggs, or native fecal samples following [[sonication]] of the eggs to release their contents.<ref name=scholz/> Another interesting potential diagnostic tool and treatment is the contrast medium, [[Gastrografin]], introduced into the duodenum, which allows both visualization of the parasite, and has also been shown to cause detachment and passing of the whole worm.<ref>Ko, S.B. “Observation of deworming process in intestinal ''Diphyllobothrium latum'' parasitism by Gastrografin injection into jejunum through double-balloon enteroscope.” (2008) from Letter to the Editor; American Journal of Gastroenterology, 103; 2149-2150.</ref>


⚫
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).<ref>{{Cite web|date=2019-05-14|title=CDC - DPDx - Diphyllobothriasis|url=https://www.cdc.gov/dpdx/diphyllobothriasis/index.html|access-date=2020-07-29|website=www.cdc.gov|language=en-us}}</ref>
==Treatment==
{{See also|Diphyllobothriasis#Treatment}}
The standard treatment for diphyllobothriasis, as well as many other tapeworm infections is a single dose of [[Praziquantel]], 5–10&nbsp;mg/kg PO once for both adults and children. An alternative treatment is [[Niclosamide]], 2 g PO once for adults or 50&nbsp;mg/kg PO once.<ref>{{cite web|url=http://www.dpd.cdc.gov/dpdx/HTML/PDF_Files/MedLetter/TapewormInfection.pdf|title=CDC - DPDx Homepage|author=|date=6 March 2018|website=www.dpd.cdc.gov|accessdate=7 April 2018}}</ref> Praziquantel is not FDA approved for this indication and Niclosamide is not available for human use in the United States.<ref>{{cite web|url=https://www.cdc.gov/parasites/diphyllobothrium/health_professionals/index.html |title=CDC - Diphyllobothrium - Resources for Health Professionals |publisher=Cdc.gov |date=2012-01-10 |accessdate=2012-12-30}}</ref>


⚫
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]], [[walleye]], and [[Esox|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 ([[bothrium|bothria]]) of their scolices. The adults can reach more than 10 m (up to 30&nbsp;ft) in length in some species such as ''D. latum,'' with more than 3,000 proglottids. One or several of the tape-like proglottid segments (hence the name tapeworm) regularly detach from the main body of the worm and release immature eggs in freshwater to start the cycle over again. Immature eggs are discharged from the proglottids (up to 1,000,000 eggs per day per worm) and are passed in the feces. The incubation period in humans, after which eggs begin to appear in the feces is typically 4–6 weeks, but can vary from as short as 2 weeks to as long as 2 years.<ref name="app.gideononline.com">{{cite web| url=https://app.gideononline.com/explore/diseases/diphyllobothriasis-10650 | title=Diphyllobothriasis | access-date=2024-02-20}}</ref>
===Side effects of treatment===
Praziquantel has few side effects, many of which are similar to the symptoms of diphyllobothriasis. They include malaise, headache, dizziness, abdominal discomfort, nausea, rise in temperature and occasionally allergic skin reactions.<ref name=scholz/> The side effects of Niclosamide are very rare, due to the fact that it is not absorbed in the gastrointestinal tract.<ref name=scholz/>


==Epidemiology==
== Disease ==
Diphyllobothriasis is considered a parasitic, zoonotic infection. ''D. latum'' causes a wide spectrum of disease and severity. The tapeworm induces changes in the concentration of several immunomodulators in the host. It can also cause structural changes in the GI tract as it modulates neuroendocrine responses and enhances secretion and gut motility. Damage may also come from the body's immune response against the worm and its millions of eggs (around 1 million/day) mediated by [[mast cell]]s, [[eosinophilic]] cell degranulations resulting to inflammatory [[cytokine]]s.<ref>Durrani MI, Basit H, Blazar E. Diphyllobothrium Latum. 2020 Jun 30. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan–. PMID 31082015.</ref> Diphyllobothriosis is considered as the most important fish-borne [[zoonosis]] with up to 20 million individuals infected.<ref>Scholz T, Garcia HH, Kuchta R, Wicht B. Update on the human broad tapeworm (genus diphyllobothrium), including clinical relevance. Clin Microbiol Rev. 2009 Jan;22(1):146-60, Table of Contents. doi: 10.1128/CMR.00033-08. PMID 19136438; PMCID: PMC2620636.</ref>
People at high risk for infection have traditionally been those who regularly consume raw fish.<ref name=scholz/> Many regional cuisines include raw or undercooked food, including sushi and sashimi in Japanese cuisine, carpaccio di persico in Italian, tartare maison in French-speaking populations, ceviche in Latin American cuisine and marinated herring in Scandinavia. With emigration and globalization, the practice of eating raw fish in these and other dishes has brought diphyllobothriasis to new parts of the world and created new endemic foci of disease.<ref name=scholz/>


''D. latum'' causes [[Vitamin B12|B12]] deficiency in humans<ref>Nyberg W, Grasbeck R, Saarni M, von Bonsdorff. Serum vitamin B12 levels and incidence of tapeworm anemia in a population heavily infected with Diphyllobothrium latum. Am J Clin Nutr. 1961 Sep-Oct;9(5):606-12. doi: 10.1093/ajcn/9.5.606. PMID 13729951.</ref> leading to [[Megaloblastic anemia|megaloblastic]] or [[Vitamin B12 deficiency anemia|pernicious]] anemia.<ref>VON BONSDORFF B. Diphyllobothrium latum as a cause of pernicious anemia. Exp Parasitol. 1956 Mar;5(2):207-30. doi: 10.1016/0014-4894(56)90015-7. PMID 13317942.</ref><ref>VON BONSDORFF B, GORDIN R. Treatment of pernicious anemia with intramuscular injections of tapeworm extracts. XIV. Diphyllobothrium latum and pernicious anemia. Acta Med Scand. 1953;144(4):263-7. doi: 10.1111/j.0954-6820.1953.tb15695.x. PMID 13039956.</ref> The worm absorbs around 80% of dietary [[Vitamin B12|B12]] and prolonged infection can also cause abdominal pain, mechanical obstruction, and symptoms of iron deficiency anemia.<ref>Sharma K, Wijarnpreecha K, Merrell N. ''Diphyllobothrium latum'' Mimicking Subacute Appendicitis. Gastroenterology Res. 2018 Jun;11(3):235-237. doi: 10.14740/gr989w. Epub 2018 May 31. PMID 29915635; PMCID: PMC5997473.</ref> Patients with prolonged infection of D. latum should be offered [[Vitamin B12|B12]] supplementation along with anti-parasitics such as [[niclosamide]] or [[praziquantel]].<ref>Vuylsteke P, Bertrand C, Verhoef GE, Vandenberghe P. Case of megaloblastic anemia caused by intestinal taeniasis. Ann Hematol. 2004 Jul;83(7):487-8. doi: 10.1007/s00277-003-0839-2. Epub 2004 Jan 17. PMID 14730392.</ref>
==Public health strategies==
The most viable interventions include: prevention of water contamination both by raising public awareness of the dangers of defecating in recreational bodies of water and by implementation of basic sanitation measures; screening and successful treatment of people infected with the parasite; and prevention of infection of humans via consumption of raw, infected fish.<ref name=scholz/> The last of these can most easily be changed via education about proper preparation of fish. Fish that is thoroughly cooked, brined, or frozen at -10&nbsp;°C for 24–48 hours can be consumed without risk of D. latum infection.


==See also==
==See also==
Line 76: Line 45:
==References==
==References==
{{Reflist}}
{{Reflist}}

⚫
*{{cite web |url=http://www.dpd.cdc.gov/dpdx/HTML/Diphyllobothriasis.htm |title=DPDx - Diphyllobothriasis |work=[[Centers for Disease Control and Prevention|CDC]] Division of Parasitic Diseases |accessdate=|date=2019-02-04 }}
==Sources==
⚫
*{{cite web |url=http://www.fda.gov/Food/FoodSafety/FoodborneIllness/FoodborneIllnessFoodbornePathogensNaturalToxins/BadBugBook/ucm070785.htm |title=UDiphyllobothrium spp. |work=[[Bad Bug Book]] |accessdate=2009-07-13}}
⚫
*{{cite web |url=http://www.dpd.cdc.gov/dpdx/HTML/Diphyllobothriasis.htm |title=DPDx - Diphyllobothriasis |work=[[Centers for Disease Control and Prevention|CDC]] Division of Parasitic Diseases |date=2019-02-04 |archive-url=https://web.archive.org/web/20071116011520/http://www.dpd.cdc.gov/DPDx/HTML/diphyllobothriasis.htm |archive-date=2007-11-16 |url-status=dead }}
⚫
*{{cite book |author1=Janovy, John |author2=Roberts, Larry S. |title=Foundations of Parasitology |publisher=McGraw-Hill Education (ISE Editions) |location= |year=2005 |edition=7th |pages= |isbn=978-0-07-111271-0 |oclc= |doi=}}
⚫
*{{cite web |url=https://www.fda.gov/Food/FoodSafety/FoodborneIllness/FoodborneIllnessFoodbornePathogensNaturalToxins/BadBugBook/ucm070785.htm |title=UDiphyllobothrium spp. |work=[[Bad Bug Book]] |access-date=2009-07-13}}
⚫
*{{cite book |author1=Janovy, John |author2=Roberts, Larry S. |title=Foundations of Parasitology |url=https://archive.org/details/geralddschmidtla0007robe |url-access=registration |publisher=McGraw-Hill Education (ISE Editions) |year=2005 |edition=7th |isbn=978-0-07-111271-0 }}
* Bonsdorff, B von: Diphyllobothriasis in Man. Academic Press, London, 1977
* Bonsdorff, B von: Diphyllobothriasis in Man. Academic Press, London, 1977
*Keas, B. E: Microscopy - Diphyllobothrium latum. Michigan State University, East Lancing, 1999
*Keas, B. E: Microscopy - Diphyllobothrium latum. Michigan State University, East Lancing, 1999


==External links==
==External links==
*http://www.stanford.edu/class/humbio103/parasites.htm
* {{ cite web| url=http://www.stanford.edu/class/humbio103/parasites.htm | archive-url=https://web.archive.org/web/20130225134229/http://www.stanford.edu/class/humbio103/parasites.htm | title=Parasites & Pestilence: ParaSite Webpages | archive-date=2013-02-25 }}


{{Helminthiases}}
{{Helminthiases}}
{{Taxonbar|from=Q600082}}
{{Taxonbar|from=Q600082}}
{{Authority control}}


[[Category:Cestoda]]
[[Category:Cestoda]]

Latest revision as of 19:03, 10 April 2024

Diphyllobothrium
Proglottids of D. latum
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Cestoda
Order: Diphyllobothriidea
Family: Diphyllobothriidae
Genus: Diphyllobothrium
Cobbold, 1858
Species
Synonyms

Cordicephalus Wardle, McLeod & Stewart, 1947

Diphyllobothrium is a genus of tapeworms which can cause diphyllobothriasis in humans through consumption of 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.[1]

Other members of the genus Diphyllobothrium include 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 only infrequently. In Japan, the most common species in human infection is D. nihonkaiense, which was only identified as a separate species from D. latum in 1986.[2] More recently, a molecular study found D. nihonkaiense and D. klebanovskii to be a single species.[3]

Morphology[edit]

Diphyllobothrium latum scolex

The adult worm is composed of three fairly distinct morphological segments: the scolex (head), the neck, and the lower body. Each side of the scolex has a slit-like groove, which is a bothrium for attachment to the intestine. The scolex attaches to the neck, or proliferative region. From the neck grow many proglottid segments which contain the reproductive organs of the worm. D. latum is the longest tapeworm in humans, averaging ten meters long. Unlike many other tapeworms, Diphyllobothrium eggs are typically unembryonated when passed in human feces.[4]

In adults, proglottids are wider than they are long (hence the name broad tapeworm). As in all pseudophyllid cestodes, the genital pores open midventrally.[5]

Life cycle[edit]

Life cycle of D. latum. Click the image to see full-size.
Diphyllobothrium latum proglottid
Diphyllobothrium latum – fertilized egg

Adult tapeworms may infect humans, canids, felines, bears, pinnipeds, and mustelids, 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 larvae. 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).[6]

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, walleye, and 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 scolices. The adults can reach more than 10 m (up to 30 ft) in length in some species such as D. latum, with more than 3,000 proglottids. One or several of the tape-like proglottid segments (hence the name tapeworm) regularly detach from the main body of the worm and release immature eggs in freshwater to start the cycle over again. Immature eggs are discharged from the proglottids (up to 1,000,000 eggs per day per worm) and are passed in the feces. The incubation period in humans, after which eggs begin to appear in the feces is typically 4–6 weeks, but can vary from as short as 2 weeks to as long as 2 years.[7]

Disease[edit]

Diphyllobothriasis is considered a parasitic, zoonotic infection. D. latum causes a wide spectrum of disease and severity. The tapeworm induces changes in the concentration of several immunomodulators in the host. It can also cause structural changes in the GI tract as it modulates neuroendocrine responses and enhances secretion and gut motility. Damage may also come from the body's immune response against the worm and its millions of eggs (around 1 million/day) mediated by mast cells, eosinophilic cell degranulations resulting to inflammatory cytokines.[8] Diphyllobothriosis is considered as the most important fish-borne zoonosis with up to 20 million individuals infected.[9]

D. latum causes B12 deficiency in humans[10] leading to megaloblastic or pernicious anemia.[11][12] The worm absorbs around 80% of dietary B12 and prolonged infection can also cause abdominal pain, mechanical obstruction, and symptoms of iron deficiency anemia.[13] Patients with prolonged infection of D. latum should be offered B12 supplementation along with anti-parasitics such as niclosamide or praziquantel.[14]

See also[edit]

References[edit]

  1. ^ Muratov, IV; Posokhov, PS (1988). "Causative agent of human diphyllobothriasis--Diphyllobothrium klebanovskii sp. n.". Parazitologiia. 22 (2): 165–70. PMID 3387122.
  2. ^ Yamane, Y; Kamo, H; Bylund, G; Wikgren, BJ (1986). "Diphyllobothrium nihonkaiense sp. nov (Cestoda: Diphyllobothriidae)---revised identification of Japanese broad tapeworm". Shimane J Med Sci. 10: 29–48.
  3. ^ Arizono, N; Shedko, M; Yamada, M; Uchikawa, R; Tegoshi, T; Takeda, K; Hashimoto, K (2009). "Mitochondrial DNA divergence in populations of the tapeworm Diphyllobothrium nihonkaiense and its phylogenetic relationship with Diphyllobothrium klebanovskii". Parasitology International. 58 (1): 22–8. doi:10.1016/j.parint.2008.09.001. PMID 18835460.
  4. ^ Ash, Lawrence; Orihel, Thomas (2007). Ash & Orihel's Atlas of Human Parasitology (5th ed.). American Society for Clinical Pathology Press.
  5. ^ Poddubnaya, Larisa G; Mackiewicz, John S; Brunanská, Magdaléna; Scholtz, Tomás (November 2005). "Fine structure of the female reproductive ducts of Cyathocephalus truncatus (Cestoda: Spathebothriidea), from salmonid fish". Folia Parasitologica. 52 (4): 323–338. doi:10.14411/fp.2005.045. PMID 16405296.
  6. ^ "CDC - DPDx - Diphyllobothriasis". www.cdc.gov. 2019-05-14. Retrieved 2020-07-29.
  7. ^ "Diphyllobothriasis". Retrieved 2024-02-20.
  8. ^ Durrani MI, Basit H, Blazar E. Diphyllobothrium Latum. 2020 Jun 30. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan–. PMID 31082015.
  9. ^ Scholz T, Garcia HH, Kuchta R, Wicht B. Update on the human broad tapeworm (genus diphyllobothrium), including clinical relevance. Clin Microbiol Rev. 2009 Jan;22(1):146-60, Table of Contents. doi: 10.1128/CMR.00033-08. PMID 19136438; PMCID: PMC2620636.
  10. ^ Nyberg W, Grasbeck R, Saarni M, von Bonsdorff. Serum vitamin B12 levels and incidence of tapeworm anemia in a population heavily infected with Diphyllobothrium latum. Am J Clin Nutr. 1961 Sep-Oct;9(5):606-12. doi: 10.1093/ajcn/9.5.606. PMID 13729951.
  11. ^ VON BONSDORFF B. Diphyllobothrium latum as a cause of pernicious anemia. Exp Parasitol. 1956 Mar;5(2):207-30. doi: 10.1016/0014-4894(56)90015-7. PMID 13317942.
  12. ^ VON BONSDORFF B, GORDIN R. Treatment of pernicious anemia with intramuscular injections of tapeworm extracts. XIV. Diphyllobothrium latum and pernicious anemia. Acta Med Scand. 1953;144(4):263-7. doi: 10.1111/j.0954-6820.1953.tb15695.x. PMID 13039956.
  13. ^ Sharma K, Wijarnpreecha K, Merrell N. Diphyllobothrium latum Mimicking Subacute Appendicitis. Gastroenterology Res. 2018 Jun;11(3):235-237. doi: 10.14740/gr989w. Epub 2018 May 31. PMID 29915635; PMCID: PMC5997473.
  14. ^ Vuylsteke P, Bertrand C, Verhoef GE, Vandenberghe P. Case of megaloblastic anemia caused by intestinal taeniasis. Ann Hematol. 2004 Jul;83(7):487-8. doi: 10.1007/s00277-003-0839-2. Epub 2004 Jan 17. PMID 14730392.

Sources[edit]

External links[edit]

Retrieved from "https://en.wikipedia.org/w/index.php?title=Diphyllobothrium&oldid=1218274593"