Case #450 – August, 2017

A 26-yo man, who recently emigrated from Northern Africa, presented to his primary care provider with complaints of abdominal pain, diarrhea, and weight loss for the preceding 6-8 months. He was later found to be leukopenic, neutropenic, with elevated eosinophils in the peripheral blood. Stool preserved in SAF was sent to the laboratory for ova and parasite examination (O&P) and the objects shown in Figures A–C were observed in a formalin-ethyl acetate (FEA) concentrate/iodine prep. What is your diagnosis? Based on what morphologic features?

This case and images were kindly provided by Cadham Provinical Public Health Laboratory, University of Manitoba, Winnipeg, Canada.

Figure A

Figure B

Figure C

This was a case of strongyloidiasis caused by Strongyloides stercoralis. Diagnostic morphologic features shown in the images included:

A short buccal cavity (arrow, Figure B).
A rhabditoid esophagus.
A prominent genital primordium (arrow, Figure C).
A tapered tail.

It should be noted that although this case was detected by the FEAC technique, this technique has a low sensitivity for the detection of S. stercoralis larvae in stool. In this case, the patient’s immunosuppression probably contributed to a high larval load, allowing it’s detection by that method. Agar plate or charcoal culture, Baermann sedimentation and PCR are all far more sensitive than FEAC methods for the detection of S. Stercoralis in stool. Serology may also prove a sensitive and effective tool for the diagnosis of strongyloidiasis.

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/.