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Monthy Case Studies - 2014

Case #371 - May, 2014

Stool specimens were collected from a 14-year-old refugee from Myanmar as part of a routine screening program. The stool was collected in 10% formalin and zinc PVA (Zn-PVA) and sent to the state health laboratory for ova-and-parasite (O&P) examination. Images of suspect parasites were captured and sent via email to the DPDx Team for diagnostic assistance. Figures A and B show two objects of interest that were observed by the attending microbiologist on a trichrome-stained slide prepared from Zn-PVA preserved stool. The measurements shown were included in the original telediagnosis submission. What is your diagnosis? Based on what criteria?

Figure A

Figure A

Figure B

Figure B

Acknowledgements: This case and images were kindly provided by the Kansas Health and Environment Laboratory, Topeka, KS.

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Answer to Case #371

This case showed trophozoites of the nonpathogenic intestinal amoeba, Entamoeba hartmanni. Diagnostic morphologic features included:

  • trophozoites within the size range (5.0-15.0 μm, with an average range of 8.0-10.0 μm) of E. hartmanni.
  • nuclei with a discrete central karyosome and evenly-distributed peripheral chromatin.

While not considered pathogenic, E. hartmanni and other nonpathogenic amoebae should be reported in all O&P examinations, as their presence may be indicative of fecal contamination of a food or water source and does not preclude the presence of other intestinal pathogens.

More on: intestinal amebae

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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: May 31, 2014
  • Page last updated: May 31, 2014
  • Content source: Global Health - Division of Parasitic Diseases and Malaria
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