Case #354 – August, 2013

A 54-year-old male from Pennsylvania presented to his health provider with fever, chills, malaise, and loss of appetite. The patient was originally from Mexico but has been living in the eastern U.S. for the past several months. A blood smear was prepared and stained with Wright’s stain. Images were captured at 1000x magnification and sent to the DPDx team for diagnostic assistance (Figures A–F). What is your diagnosis? Based on what criteria? What other tests, if any, would you recommend?

Figure A

Figure B

Figure C

Figure D

Figure E

Figure F

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.
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.