Case #414 - February 2016
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Case Description
A 7-year-old boy was presented to his health care provider with symptoms of intermittent diarrhea, abdominal pain and loss of appetite. A stool specimen was collected in 10% formalin and zinc PVA (Zn-PVA) for routine ova-and-parasite (O&P) examination. Figures A-F show what was observed at 1000x magnification with oil on a trichrome-stained smear made from stool preserved in the Zn-PVA. The objects of interest measured 7-13 µm. Figures A and B show the same object at different focal planes. What is your diagnosis? Based on what criteria?
Figure A
Figure B
Figure C
Figure D
Figure E
Figure F
Case Answer
This was a case of Dientamoeba fragilis infection. Diagnostic features shown included:
- trophozoites with one or two nuclei with clusters of karyosomal chromatin and no peripheral chromatin.
- trophozoites within the size range consistent for D. fragilis (5-15µm).
More on: Dientamoeba fragilis
DPDx is an education resource designed for health professionals and laboratory scientists. For an overview including prevention and control visit www.cdc.gov/parasites/.
- Page last reviewed: August 24, 2016
- Page last updated: August 24, 2016
- Content source:
- Global Health – Division of Parasitic Diseases and Malaria
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