Case #510 - February, 2020
A 29-year-old man sought medical attention with his health care provider with a complaint of itchy maculopapular rash on several areas of his body. He reported travel to the Philippines, where he swam in fresh water while visiting the islands of Luzon and Mindanao. His health care provider requested a stool specimen for ova and parasite (O & P) testing. The sample was concentrated by the formalin-ethyl acetate method, and a wet mount smear made from the sediment and examined. A few objects of interest were detected. Figures A and B show the same object at different focal planes and Figures C and D show another object, also at different focal planes; both objects shown are at 200x magnification. What is your diagnosis? Based on what criteria?
This was a case of schistosomiasis caused by Schistosoma japonicum. Morphologic features shown in the Figures A and B, and C and D included:
- Large, rounded/oval eggs within the size range for S. japonicum (70—100 x 55—64 µm).
- Presence of a small spine (shown at a different focal plane in Figures B and D) consistent with S. japonicum (arrows in Figures B and D).
- Presence of a miracidium within the eggs (the shape of the miracidium and the geographical origin excludes S. mekongi).
Clinical presentation of maculopapular rash and travel history of the patient were also compatible with S. japonicum infections. There is also a serologic test available to detect antibodies against S. japonicum.
More on schistosomiasis
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/.