関: Dientamoeba fragilis

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/12/08 17:02:16」(JST)

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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.

Etymology

Di refers to the two nuclei in the trophozoites (feeding stage of the organism).
Ent refers to the enteric environment in which the organism is found.
The species name fragilis refers to the fact that the trophozoite stages are fragile; they do not survive long in the stool after leaving the body of the human host.

It was first described in 1918.^[2]

Dientamoebiasis

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]

Phylogenetics

Dientamoeba fragilis is a type of trichomonad. Trichomonads are flagellated organisms but D. fragilis lacks flagella,^[4] 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.

\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.

Build

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]

References

^ Windsor JJ, Macfarlane L (May 2005). "Irritable bowel syndrome: the need to exclude Dientamoeba fragilis". Am. J. Trop. Med. Hyg. 72 (5): 501; author reply 501–2. PMID 15891119.
^ Johnson EH, Windsor JJ, Clark CG (July 2004). "Emerging from obscurity: biological, clinical, and diagnostic aspects of Dientamoeba fragilis". Clin. Microbiol. Rev. 17 (3): 553–70, table of contents. doi:10.1128/CMR.17.3.553-570.2004. PMC 452553. PMID 15258093.
^ Stark D, Beebe N, Marriott D, Ellis J, Harkness J (June 2005). "Prospective study of the prevalence, genotyping, and clinical relevance of Dientamoeba fragilis infections in an Australian population". J. Clin. Microbiol. 43 (6): 2718–23. doi:10.1128/JCM.43.6.2718-2723.2005. PMC 1151954. PMID 15956388.
^ Lagacé-Wiens PR, VanCaeseele PG, Koschik C (August 2006). "Dientamoeba fragilis: an emerging role in intestinal disease". CMAJ 175 (5): 468–9. doi:10.1503/cmaj.060265. PMC 1550747. PMID 16940260.
^ Munasinghe, V. S.; Vella, N. G.; Ellis, J. T.; Windsor, P. A.; Stark, D (2013). "Cyst formation and faecal-oral transmission of Dientamoeba fragilis--the missing link in the life cycle of an emerging pathogen". International Journal for Parasitology 43 (11): 879–83. doi:10.1016/j.ijpara.2013.06.003. PMID 23872523. edit
^ Tachezy, Jan: Hydrogenosomes and mitosomes: mitochondria of anaerobic eukaryotes ISBN 978-3-642-09542-9

External links

http://www.dpd.cdc.gov/dpdx/HTML/Dientamoeba.htm
http://www.emedicine.com/ped/topic563.htm
Dientamoeba Fragilis Infection

UpToDate Contents

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1. 二核アメーバ dientamoeba fragilis
2. 抗原虫治療 antiprotozoal therapies
3. 原因不明の好酸球増加症患者に対するアプローチ approach to the patient with unexplained eosinophilia
4. 非病原性腸内原虫 nonpathogenic enteric protozoa
5. ジアルジア症の疫学、臨床症状、および診断 epidemiology clinical manifestations and diagnosis of giardiasis

English Journal

Detection of Dientamoeba fragilis in Portuguese children with acute gastroenteritis between 2011 and 2013.

Júlio C1, Furtado C2, Rocha R1, Escobar C3, Brito MJ4, Oleastro M1.
Parasitology.Parasitology.2015 Jul 21:1-6. [Epub ahead of print]
Dientamoeba fragilis is an inhabitant of human gastrointestinal tract with a worldwide distribution. The first description considered this protozoan a rare and harmless commensal, since then it has struggled to gain recognition as a pathogen. Commercial multiplex real-time PCR was used to detect D.
PMID 26194017

Dientamoeba fragilis prevalence coincides with gastrointestinal symptoms in children less than 11 years old in Sweden.

Ögren J1, Dienus O, Löfgren S, Einemo IM, Iveroth P, Matussek A.
European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology.Eur J Clin Microbiol Infect Dis.2015 Jul 15. [Epub ahead of print]
Dientamoeba fragilis is a protozoan with a debated role in gastrointestinal (GI) disease. Although correlated to GI symptoms, no virulence factors have been described. In this study, we evaluated the cause of GI symptoms in children at two schools, with children aged 1 to 10 years, in the county of
PMID 26173693

Donor Recruitment for Fecal Microbiota Transplantation.

Paramsothy S1, Borody TJ, Lin E, Finlayson S, Walsh AJ, Samuel D, van den Bogaerde J, Leong RW, Connor S, Ng W, Mitchell HM, Kaakoush N, Kamm MA.
Inflammatory bowel diseases.Inflamm Bowel Dis.2015 Jul;21(7):1600-6. doi: 10.1097/MIB.0000000000000405.
BACKGROUND: Increasing demand for fecal microbiota transplantation (FMT) has created a need for stool banks sourced from long-term healthy donors. Here, we describe our experience in recruiting and screening fecal donors.METHODS: Mailbox, newspaper, and online advertisements were used. Potential don
PMID 26070003

Japanese Journal

Transmission of Dientamoeba fragilis : Evaluation of the role of Enterobius vermicularis

GIRGINKARDESLER Nogay,KURT Ozgur,KILIMCIOGLU Ali A.,OK Ulgen Z.
Parasitology international : official journal of the Japanese Society of Parasitology 57(1), 72-75, 2008-03-01
NAID 10020151219

Prospective study of the prevalence, genotyping, and clinical relevance of Dientamoeba fragilis infections in an Australian population

STARK D
Int J Parasitol 35(1), 57-62, 2005
NAID 30006420386

Chronic diarrhea and protein-losing gastroenteropathy caused by Dientamoeba fragilis

ITO Reiko,SAKAGAMI Junichi,KATAOKA Keisho,NAKAMURA Hideo,MOTOYOSHI Tomoko,TAKADA Ryusuke,KANEMITSU Daisuke,YASUDA Hiroaki,MITSUFUJI Shoji,OKANOUE Takeshi
Journal of gastroenterology 39(11), 1117-1119, 2004-11-01
NAID 10014116466

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「二核アメーバ属」

Dientamoeba fragilis
Scientific classification
Domain:	Eukaryota
Kingdom:	Excavata
Phylum:	Metamonada
Class:	Parabasalia
Order:	Trichomonadida
Family:	Monocercomonadidae
Genus:	Dientamoeba
Species:	D. fragilis
Binomial name
	Dientamoeba fragilis;