Case #480 - November, 2018
A man from New England returned from a trip to Africa with fever, chills, sweats, and fatigue. He sought medical attention from his health care provider. A blood smear was ordered, prepared, stained with Wright-Giemsa and examined. A diagnosis of Babesia was made. The slides and a blood specimen were sent to the CDC for confirmation. Figures A-D show what was observed at 1000x oil magnification on one of the stained blood smears. What is your diagnosis? Based on what criteria?
This was a case of malaria caused by Plasmodium falciparum. Diagnostic morphologic features shown, some of which also ruled out babesiosis, included:
- Thin, delicate rings, some presenting double chromatin dots
- Developing trophozoites with a few presenting malarial pigment (arrows Figure A)
- Macrophages presenting engulfed malarial pigment (arrows Figure C)
- Absence of pleomorphic parasites
There was some atypical presentation of the parasites in this case, such as extracellular parasites (Figure D, blue arrow) and even a multiply infected rbc with four parasites somewhat resembling a “Maltese Cross” (Figure D, blue arrow). However, even in this field one can see malarial pigment present in a developing trophozoite.
More on malaria: https://www.cdc.gov/dpdx/malaria/index.html
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 education resource designed for health professionals and laboratory scientists. For an overview including prevention and control visit www.cdc.gov/parasites/.