Case #508 – January, 2020

A 69-year-old male patient from a rural town in Georgia experiencing symptoms of productive cough with blood, hematochezia (rectal bleeding) and chest pain sought medical attention at the county health clinic. He had no known travel history. A bronchoalveolar wash specimen was collected in Total-Fix® and sent to the laboratory for analysis. Microscopic examination of a wet mount preparation revealed what is shown in the following images (Figures A–C) captured at different magnifications. The organisms measured 271-378 µm. What is your diagnosis? Based on what criteria?

Figure A

Figure B

Figure C

This was a case of strongyloidiasis caused by the roundworm Strongyloides stercoralis. Although the immune status of patient was not provided, this case was suggestive of hyperinfection resulting from autoinfection commonly seen in immunosuppressed patients. In autoinfection, rhabditiform larvae that hatch in the intestinal mucosa become filariform larvae, penetrate the mucosa and are carried to the lungs, pharynx and small intestine or disseminate throughout the body. Diagnostic morphologic features shown in the images included:

Figure C

Size range consistent with filariform larvae of Strongyloides stercoralis (measures up to 600 µm long).
Short inconspicuous buccal canal (Figure C Answer, green arrow).
Approximately 1:1 ratio of the length of the esophagus (red line) to intestine (blue line); 147:149 (Figure C Answer).
Inconspicuous genital primordium.
Notched tail, (insert, Figure C Answer).