Case #518 – June, 2020

A 24-year-old man from Thailand presented to his healthcare provider with complaints of gastrointestinal pain and weight loss. He also reported seeing thin worms in his stool on rare occasion. A stool specimen was collected, and two worms were recovered and examined. Figure A shows the worms at 40X magnification and Figures B and C at 100X magnifications. What is your diagnosis? Based on what criteria?

Figure A

Figure B

Figure C

This was a case of intestinal capillariasis caused by Capillaria philippinensis. Diagnostic morphological features included:

Very thin nematodes with stichocytes visible (Figures B and C)
Eggs in utero consistent with those of Capillaria philippinensis (Figure C)

Intestinal capillariasis is endemic in the Philippines, as the name of the parasite suggests, as well as Thailand; sporadic cases have been reported in Egypt. Stichocytes are specialized cells found surrounding the esophagus in nematodes in the families of Capillariidae, Trichinellidae, Trichuridae, and Anatrichosomatidae. Typically, a diagnosis of intestinal capillariasis is made by the detection of eggs in stool; however, larvae and adult worms can also be found.