Case #269 – February, 2010

A 29-year-old woman had complaints of abdominal cramping and diarrhea that had been persisting for 5 days. She went to a local clinic to determine what was causing her illness. A stool specimen was collected in formalin and sent to the State Public Health Laboratory for routine ova-and-parasite (O&P) examination. A wet mount preparation was made after concentrating the specimen and was examined. The technician noticed suspicious round objects and suggested that a Kinyoun’s modified acid-fast stain be performed. Figures A–C show what was found on the acid-fast stained fecal smear. What is your diagnosis? Based on what criteria?

Figure A

Figure B

Figure C

This case represented a mixed infection with Cyclospora sp. and Cryptosporidium sp. Diagnostic morphologic features shown in the figures were:

a size range for the unstained objects which was consistent with Cyclospora sp. (blue arrow, Figure A).
unstained oocysts with a wrinkled appearance in the modified acid-fast stain, another characteristic of Cyclospora sp. All of the oocysts shown in this case were unstained, which is not uncommon.
a size range for the stained objects which was consistent with Cryptosporidium sp. (red arrow, Figure A).
the presence of sporozoites in some of the Cryptosporidium oocysts.

Morphology can only identify Cryptosporidium and Cyclospora to the genus level. Molecular testing (PCR) of appropriate specimens should be performed to identify the parasites to the species level.

Figure A

More on: Cryptosporidiosis: Cyclosporiasis

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.