Case #346 – April, 2013
A 21-year-old exchange student from Nepal sought medical attention for intermittent diarrhea associated with mild abdominal cramps. A stool specimen was collected for laboratory testing in low viscosity polyvinyl alcohol (LV-PVA). A smear was made from the preserved stool and stained with trichrome. Figures A–D show what was observed in moderate numbers at 1000x magnification with oil; Figures A and B show the same object in different focal planes. The size of the objects ranged from 15-20 micrometers in diameter. What is your diagnosis? Based on what criteria?
The organisms observed were cysts of Entamoeba polecki, which is generally considered to be a nonpathogenic amoeba that can reside in the large intestine. Morphologic features shown included:
- cysts within the size range (9-24 micrometers) for the species.
- the presence of a large, irregular nucleus with a pleomorphic karyosome.
- the presence of numerous irregular, red-staining chromatoid bodies.
More on:Entamoeba polecki
Images presented in the DPDx case studies are from specimens submitted for diagnosis or archiving. On rare occasions, clinical histories given may be partly fictitious.
DPDx is an educational resource designed for health professionals and laboratory scientists. For an overview including prevention, control, and treatment visit www.cdc.gov/parasites/.