Case #406 – October 2015

Stool specimens were collected from a 27-year-old girl from Chad as part of a refugee screening program. The stool was collected in 10% formalin and zinc PVA (Zn-PVA) and sent to the county health department for routine ova-and-parasite (O&P) examination. Figures A–D show what was observed at 1000x magnification with oil on a trichrome-stained slide made from stool preserved in Zn-PVA. The objects shown measured 10-12 µm in length, on average. What is your diagnosis? Based on what criteria?

Figure A

Figure B

Figure C

Figure D

The objects seen in the images are leukocytes (white blood cells). Large numbers of white blood cells (WBCs) are often found in patients with bacterial infections and therefore other tests should be considered. Some types of leukocytes can resemble trophozoites of Entamoeba species, but lack the characteric nuclei containing a single, defined karyosome and peripheral chromatin.