Case #357 – October, 2013

A 59-year-old man required emergency medical attention due to hyperpyrexia (>40° C/104° F), generalized convulsions, and signs of renal failure. The patient’s recent travel history was not available. Blood specimens were collected in EDTA for routine work up. In addition, STAT blood smears were ordered, stained with Wright stain, and examined. Figures A–I show what was observed at 1000x magnification. The images in Figures A–C were taken from a thick film; the images in Figures D–I were taken from a thin film. What is your diagnosis? Based on what criteria?

Figure A

Figure B

Figure C

Figure D

Figure E

Figure F

Figure G

Figure H

Figure I

This was a case of malaria caused by Plasmodium falciparum. In naïve (nonimmune) individuals, hyperparasitemia (>5% parasitized erythrocytes or > 250,000 parasites/μl) and the presence of more mature forms such as late trophozoites, schizonts, and gametocytes, are indicators of severe malaria. Morphologic features shown in the figures included:

late compact trophozoites in normal-sized erythrocytes.
elongate and “banana-shaped” gametocytes consistent with P. falciparum (Figures E, F, and G).
schizonts with approximately 16-18 small merozoites in a normal-sized erythrocyte (Figures A–E, I).
thin, delicate rings (Figures H and I).