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 B

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.