Case #492 – May, 2019

A journalist, who had been on location in Thailand for one week, started to experience abdominal/gastrointestinal symptoms including borborygmus (rumbling stomach), abdominal pain, and diarrhea about 3 weeks after returning home and therefore sought medical attention. A stool specimen was collected and tested for ova-and-parasites (O & P). Figures A–C show what was detected in a wet prep stool smear made from the sediment of a formalin-ethyl acetate concentration procedure. Figures B and C are of the same object at slightly different planes of focus. (Note: all figures have a scale bar in the lower right corner.) What is your diagnosis? Based on what criteria?

Figure A

Figure B

Figure C

This was a case of intestinal capillariasis caused by Capillaria phillippinensis. Morphologic features shown in the images included:

unembryonated eggs within the size range for C. phillippinensis (35-45 micrometers).
eggs with a striated shell and polar prominences that are somewhat inconspicuous.

Eggs of C. phillippinensis may somewhat resemble eggs of Trichuris trichuria however, the shape of T. trichuria eggs is prolate spheroid (like an American football), have more prominent polar prominences, do not have a striated shell, and are slightly larger (50-55 micrometers).

More on intestinal capillariasis: https://www.cdc.gov/dpdx/intestinalcapillariasis/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.