Case #365 - February 2014
A 21-year-old immigrant from North Africa had a routine ova-and-parasite (O&P) stool exam performed as part of a refugee screening program. Figures A–H show examples of what was observed on a wet mount made from the sediment of a formalin-ethyl acetate (FEA) concentration of the stool. Figures A–D were captured at 200x magnification. Figures E–H were captured at 1000x magnification with oil; the objects shown therein measured 12-18 micrometers on average. What is your diagnosis? Based on what criteria?
This was a case of schistosomiasis caused by Schistosoma mansoni. Also present were cysts and trophozoites of Entamoeba polecki. Diagnostic features included:
- presence of S. mansoni eggs demonstrating the prominent lateral spine, which was visible in different focal planes (Figures B and D). Suspicious objects should be studied in different focal planes, as key diagnostic features may be overlooked.
- presence of a miracidium within the eggs (Figures A and D).
- presence of trophozoites of E. polecki with a large, irregular nucleus containing a pleomorphic karyosome (Figures F and H).
- presence of cysts of E. polecki with numerous irregular chromatoid bodies (Figures E, G and H).
More on schistosomiasis; intestinal amebae
This case, and the specimen from which images were taken, were kindly provided by the Cadham Provincial Laboratory, Winnipeg, Canada.
Images presented in the monthly 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/.