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 pseudophyllidcestode 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]
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
Life cycle of D. latum. Click the image to see full-size.Diphyllobothrium latum proglottidDiphyllobothrium 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 procercoidlarvae. 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
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 must also undergo B12 supplementations along with anti-parasitics such as niclosamide or praziquantel.[14]
^Muratov, IV; Posokhov, PS (1988). "Causative agent of human diphyllobothriasis--Diphyllobothrium klebanovskii sp. n.". Parazitologiia. 22 (2): 165–70. PMID 3387122.
^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.
^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.
^Ash, Lawrence; Orihel, Thomas (2007). Ash & Orihel's Atlas of Human Parasitology (5th ed.). American Society for Clinical Pathology Press.
^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.
^Durrani MI, Basit H, Blazar E. Diphyllobothrium Latum. 2020 Jun 30. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan–. PMID 31082015.
^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.
^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.
^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.
^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.
^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
. CDC Division of Parasitic Diseases. 2019-02-04. Archived from the original on 2007-11-16.
"UDiphyllobothrium spp". Bad Bug Book. Retrieved 2009-07-13.
Janovy, John; Roberts, Larry S. (2005). Foundations of Parasitology (7th ed.). McGraw-Hill Education (ISE Editions). ISBN978-0-07-111271-0.
Bonsdorff, B von: Diphyllobothriasis in Man. Academic Press, London, 1977
Keas, B. E: Microscopy - Diphyllobothrium latum. Michigan State University, East Lancing, 1999
diphyllobothrium, this, article, uses, bare, urls, which, uninformative, vulnerable, link, please, consider, converting, them, full, citations, ensure, article, remains, verifiable, maintains, consistent, citation, style, several, templates, tools, available, . This article uses bare URLs which are uninformative and vulnerable to link rot Please consider converting them to full citations to ensure the article remains verifiable and maintains a consistent citation style Several templates and tools are available to assist in formatting such as Reflinks documentation reFill documentation and Citation bot documentation August 2022 Learn how and when to remove this template message 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 DiphyllobothriumProglottids of D latumScientific classificationDomain EukaryotaKingdom AnimaliaPhylum PlatyhelminthesClass CestodaOrder DiphyllobothriideaFamily DiphyllobothriidaeGenus DiphyllobothriumCobbold 1858SpeciesD pacificumD cordatum Diphyllobothrium elegans Diphyllobothrium latum Linnaeus 1757D ursiD dendriticumD lanceolatumD dalliaeD yonagoensisD nihonkaiense D klebanovskiiSynonymsCordicephalus Wardle McLeod amp Stewart 1947Other 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 Contents 1 Morphology 2 Life cycle 3 Disease 4 See also 5 References 6 Sources 7 External linksMorphology Edit Diphyllobothrium latum scolexThe 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 eggAdult 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 EditDiphyllobothriasis 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 must also undergo B12 supplementations along with anti parasitics such as niclosamide or praziquantel 14 See also EditList of parasites human References Edit Muratov IV Posokhov PS 1988 Causative agent of human diphyllobothriasis Diphyllobothrium klebanovskii sp n Parazitologiia 22 2 165 70 PMID 3387122 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 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 Ash Lawrence Orihel Thomas 2007 Ash amp Orihel s Atlas of Human Parasitology 5th ed American Society for Clinical Pathology Press Poddubnaya Larisa G Mackiewicz John S Brunanska Magdalena Scholtz Tomas 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 CDC DPDx Diphyllobothriasis www cdc gov 2019 05 14 Retrieved 2020 07 29 http web gideononline com web epidemiology Durrani MI Basit H Blazar E Diphyllobothrium Latum 2020 Jun 30 In StatPearls Internet Treasure Island FL StatPearls Publishing 2020 Jan PMID 31082015 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 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 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 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 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 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 DPDx Diphyllobothriasis CDC Division of Parasitic Diseases 2019 02 04 Archived from the original on 2007 11 16 UDiphyllobothrium spp Bad Bug Book Retrieved 2009 07 13 Janovy John Roberts Larry S 2005 Foundations of Parasitology 7th ed McGraw Hill Education ISE Editions ISBN 978 0 07 111271 0 Bonsdorff B von Diphyllobothriasis in Man Academic Press London 1977 Keas B E Microscopy Diphyllobothrium latum Michigan State University East Lancing 1999External links Edithttp www stanford edu class humbio103 parasites htm Retrieved from https en wikipedia org w index php title Diphyllobothrium amp oldid 1107476362, wikipedia, wiki, book, books, library,
