Dientamoeba fragilis: D.fragilis is a trichomonad flagellate that lives in the large intestine of humans, associated with gastrointestinal illness (nausea, anorexia, diarrhea, flatulence, abdominal pain); many infections are asymptomatic. The name refers to the fact that is an enteric binucleate parasite that tends to degenerate rapidly after excretion in stool. Geographical distribution: worldwide. Transmission: fecal-oral or via helminth eggs (pinworm). Diagnosis: only trophozoites with one or two nuclei can be observed in fixed stools or in permanent stained smears. In direct saline preparations D. fragilis appears rounded with a wide range of size: between 6 to 12 μm. The trophozoite form is the only stage found in stools. Bibliography: Eugene H. Johnson et al. Emerging from Obscurity: Biological, Clinical, and Diagnostic Aspects of Dientamoeba fragilis Clin Microbiol Rev. 2004;17(3): 553–570 Dientamoeba fragilis trophopzoites in permanent smear stained with Iron-Hematoxylin
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