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Dientamoeba fragilis Infection

[Dientamoeba fragilis]

 Binucleate forms of trophozoites of D. fragilis, stained with trichrome.

Binucleate form of a trophozoite of Dientamoeba fragilis, stained with trichrome.

Uninucleate forms of trophozoites of D. fragilis, stained with trichrome.

Uninucleate form of a trophozoite of D. fragilis, stained with trichrome.

Causal Agents

Despite its name, Dientamoeba fragilis is not an ameba but a flagellate. This protozoan parasite produces trophozoites; cysts have not been identified. Infection may be either symptomatic or asymptomatic.

Life Cycle

Life cycle of Dientamoeba

The complete life cycle of this parasite has not yet been determined, but assumptions were made based on clinical data. To date, the cyst stage has not been identified in D. fragilis life cycle, and the trophozoite is the only stage found in stools of infected individualsThe Number 1. D. fragilis is probably transmitted by fecal-oral routeThe Number 2 and transmission via helminth eggs (e.g., Ascaris, Enterobius spp.) has been postulatedThe Number 3. Trophozoites of D. fragilis have characteristically one or two nuclei (The Number 1, The Number 4 ), and it is found in children complaining of intestinal (e.g., intermittent diarrhea, abdominal pain) and other symptoms (e.g., nausea, anorexia, fatigue, malaise, poor weight gain).

Geographic Distribution


Clinical Presentation

Symptoms that have been associated with infection include diarrhea, abdominal pain, anorexia, nausea, vomiting, fatigue, and weight loss.

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  • Page last reviewed November 29, 2013
  • Page last updated November 29, 2013
  • Content source: Global Health - Division of Parasitic Diseases and Malaria
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