Monthy Case Studies - 2014
Case #368 - March, 2014
An eight-year-old child presented to a hospital with intermittent fevers. He had recently returned from a trip to Kenya and had not taken anti-malarial prophylaxis while traveling. Blood was collected in EDTA and sent for hematologic work-up. A BinaxNOW malarial antigen test was performed and the result was negative. Thin smears were also made and stained with Wright-Giemsa. The attending technologist who read the smears took digital images of her findings and sent them to the DPDx Team for a telediagnosis consult. Figures A-D show four of the images received for analysis. What is your diagnosis? Based on what criteria?
Acknowledgements: This case and images were kindly provided by the University of Washington Medical Center, Seattle, WA.
Answer to Case #368
This was a case of malaria caused by Plasmodium ovale. Diagnostic morphologic features included:
- compact developing trophozoites.
- Schüffner’s stippling (Figures B-D). Schüffner’s stippling is often less pronounced or absent in Wright-Giemsa stained smears than with traditional Giemsa-stained smears.
- elongation and fimbriation of infected RBCs (Figures A and D).
The negative result in the BinaxNOW antigen test could be due to the lower sensitivity of this test for P. ovale than for P. falciparum.
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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.