Case #452 – September, 2017

A man, with no reported travel outside of Canada and who was immunocompetent, had complaints of abdominal cramping and diarrhea that had been ongoing for more than two weeks. A stool specimen was collected for ova-and-parasite (O & P) examination which included a formalin-ethyl acetate concentration (FEA) and subsequent iron hematoxylin –modified acid-fast combination stain. Figure A shows what was detected on a wet mount prep and Figures B and C on the combination stained fecal smear. Objects of interest measured 25-30 micrometers on average. What is your diagnosis? Based on what criteria?

This case and images was kindly provided by the Cadham Provincial Public Health Laboratory, Winnipeg, MB

Figure A

Figure B

Figure C

This was a case of cystoisosporiasis caused by Cystoisospora belli. Morphologic diagnostic features shown included:

A thin walled, ellipsoidal shaped oocyst that contained a single sporoblast (Figure A). Mature oocysts of C. belli normally contain two sporoblasts.
Modified acid-fast staining oocyst consistent with C. belli (Figures B & C)

More on: https://www.cdc.gov/dpdx/cystoisosporiasis/index.html

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/.