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Case #334 - October, 2012

During the laboratory component of the DPDx Diagnostic Parasitology Workshop on Intestinal Parasites, a participant made an observation on a trichrome-stained fecal smear and wanted to share with the class. The images in Figures A and B were captured at 1000x oil magnification. The two images show the same object in different focal planes. What is your diagnosis? Based on what criteria?


Figure A


Figure B

Case Answer

The figures showed a trophozoite of Entamoeba coli with an ingested cyst of Giardia duodenalis. Diagnostic features included:

  • an amoeba trophozoite with coarse cytoplasm and within the size range for E. coli.
  • a single nucleus with an eccentric karyosome.
  • a large vacuole that contained a cyst within the size range for G. duodenalis demonstrating intracytoplasmic fibrils, two nuclei.

More on: Giardiasis: Entamoeba coli

Images presented in the monthly case studies are from specimens submitted for diagnosis or archiving. On rare occasions, clinical histories given may be partly fictitious.

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  • Page last reviewed: August 24, 2016
  • Page last updated: August 24, 2016
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