Diagnostic Findings [Last Modified: ]
Dientamoeba fragilis infection
[Dientamoeba fragilis]
Causal Agent Life Cycle Geographic Distribution Clinical Features Laboratory Diagnosis Treatment

Microscopy

Dientamoeba fragilis is a flagellate that must be morphologically differentiated from the small nonpathogenic amebas.  Dientamoeba fragilis has no cyst stage, and its trophozoites measure 5 to 15 µm.  The flagella is not usually evident and the pseudopodia are angular to broad-lobed and transparent.  While most trophozoites are typically binucleate, some have only one nucleus.

Dientamoeba, trichrome stain Dientamoeba, trichrome stain
A B

A, B:  Binucleate forms of trophozoites of D. fragilis, stained with trichrome.

Dientamoeba, trichrome stain Dientamoeba, trichrome stain
C D

C:  Binucleate form of a trophozoite of D. fragilis, stained with trichrome.
D:  Binucleate and uninucleate forms of trophozoites of D. fragilis, stained with trichrome.

Dientamoeba, trichrome stain Dientamoeba with Blastocystis
E F

E:  Uninucleate form of a trophozoite of D. fragilis.
F:  Binucleate form of a trophozoite of D. fragilis, stained with trichrome.  A cyst-like form of Blastocystis hominis lies to the left of the D. fragilis.

 
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