Case #431 – November, 2016
A 62-year-old man from Kenya had been living in rural Connecticut with relatives for 6 months when he developed fever, chills, and fatigue. The family took him to their health care provider for medical attention. Blood work-up revealed anemia and blood smears were prepared, stained, and examined. Figures A–I show what was found on thin smears. What is your diagnosis? Based on what criteria?
This was a case of babesiosis caused by Babesia sp. Morphologic features included:
- pleomorphic and vacuolated intraerythrocytic ring-like parasites in normal-sized red blood cells.
- extra-erythrocytic presentation of parasites (Figure I).
- an absence of malarial pigment found in Plasmodium species.
Identification of Babesia to the species or strain level is not possible by morphology and requires molecular analysis of a blood specimen. Follow-up on this case included an EDTA blood specimen for PCR and the result was B. microti.
More on: Babesiosis
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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/.