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Dientamoeba fragilis is a single-celled parasite found in the gastrointestinal tract of some humans, pigs and gorillas. It causes gastrointestinal upset in some people, but not in others.[1] It is an important cause of travellers diarrhoea, chronic diarrhoea, fatigue and, in children, failure to thrive.
It was first described in 1918.[2]
Infection with D. fragilis, called dientamoebiasis, is associated variously with symptoms of abdominal pain, diarrhea, weight loss, and fever. In one study, D. fragilis was identified in 0.9% of patients observed. Its coincidence with enterobiasis has been reported.[3]
Dientamoeba fragilis is a type of
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replicates by binary fission, moves by pseudopodia, and feeds by phagocytosis. The cytoplasm typically contains numerous food vacuoles that contain ingested debris, including bacteria. Waste materials are eliminated from the cell through digestive vacuoles by exocytosis. D. fragilis possesses some flagellate characteristics. In the binucleate form is a spindle structure located between the nuclei, which stems from certain polar configurations adjacent to a nucleus; these configurations appear to be homologous to hypermastigotes’ atractophores. A complex Golgi apparatus is seen; the nuclear structure of D. fragilis is more similar to that of flagellated trichomonads than to that of Entamoeba. Also notable is the presence of hydrogenosomes, which are also a characteristic of other trichomonads.[6]
\n completely determined, but some assumptions have been made based on clinical data. Recently, a cyst stage has been reported,[5] although it is yet to be independently confirmed. If true, D. fragilis is probably transmitted by the fecal-oral route. Prior to the report of this cyst stage in the lifecycle of Dientamoeba, transmission was postulated to occur by helminth eggs (e.g., Ascaris, Enterobius spp.). The rationale for this suggestion was that D. fragilis is closely related to the turkey parasite Histomonas, which is known to be transmitted by the eggs of the helminth Heterakis.
having secondarily 'lost' them over evolutionary time. Thus, it is an amoeba of flagellate ancestry. In point of ultrastructural and antigenic view, Dientamoeba is reclassified as a flagellate. [4]
Euglenozoa, Loukozoa, Apusozoa, Spironemidae, Biological classification
Kingdom (biology), Phylum, Aristotle, Order (biology), Taxon, John Ray
Malaria, Medical Subject Headings, Excavata, Cancer, Coccidia
Percolozoa, Parabasalia, Biological classification, Carpediemonas, Loukozoa
Percolozoa, Excavata, Biological classification, Loukozoa, Trichozoa
Giardia, H. pylori, World War II, Bacteria, Genetics
Biological classification, Eukaryote, Excavata, Parabasalid, Protist
Entamoeba histolytica, Bacteria, Cancer, Africa, Iodine
Excavata, Biological classification, Eukaryote, Euglenozoa, Trypanosomatida