Encyclopedia of Parasitology

Living Edition
| Editors: Heinz Mehlhorn

Dientamoeba fragilis

  • Heinz Mehlhorn
Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-27769-6_880-2


Greek: di = double, twofold; entos = inside; amoibe = changing shape; Latin: fragilis = fragile.

Geographic Distributions/Epidemiology

Worldwide distributed. Prevalence rates between 0.4 % and 42 % have been reported in several worldwide investigations (e.g. 9.4 % USA; 16 % British Isles).

Morphology/Life Cycle

The amoeboid trophozoites of D. fragilis live in the intestinal tractus (mainly colon) of humans and primates, reach a size of 3–12 μm and contain often two nuclei (Fig. 1). This is apparently the stage prior to division. The nuclei contain of condensations. In feces and in the terminal regions often 10 μm sized, thin-walled, spherical cysts occur (Fig. 2). At the beginning of their discovery history Dientamoeba was classified as a non-pathogenic commensal. However, the recent molecular biological studies showed that they are closely related to Trichomonas species and that they have a considerable pathogenic potential.


Drinking Water Irritable Bowel Syndrome Intestinal Tractus Terminal Region Pathogenic Potential 
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Further Reading

  1. Clark CG et al (2014) Transmission of Dientamoeba fragilis: pinworm or cyst? Trends Parasitol 30:136–139CrossRefPubMedGoogle Scholar
  2. Jepps MW, Dobell C (1918) Dientamoeba fragilis n.g., n.sp. new intestinal amoeba from man. Parasitology 10:352–367CrossRefGoogle Scholar
  3. Stark D et al (2010) A review of the clinical presentation. Am J Trop Med Hyg 82:614–619CrossRefPubMedPubMedCentralGoogle Scholar
  4. Vandenberg O et al (2006) Clinical and microbiological features of dientamoebiasis in patients suspected of suffering from parasitic gastrointestinal illness: a comparison of Dientamoeba fragilis and Giardia lamblia infections. Int J Infect Dis 10:255–261CrossRefPubMedGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  1. 1.Institut für Zoomorphologie, Zellbiologie und ParasitologieHeinrich-Heine-UniversitätDüsseldorfGermany