Case #202 – April, 2007

A patient was seen at a hospital in Rwanda with headache, fever, and chills. A thin blood smear was made, stained with Giemsa, and examined. Figures A-F show what was seen on the smear at 1000× magnification. What is your diagnosis? Based on what criteria?

Figure A

Figure B

Figure C

Figure D

Figure E

Figure F

This was a case of malaria caused by Plasmodium ovale. Many of the images depicted a classic presentation of P. ovale morphology; diagnostic features included:

enlarged infected RBCs (1 1/4 to 1 1/2×).
the presence of Schϋffner’s dots in the infected RBCs.
elongated and fimbriated RBCs.
the presence of multiple stages of Plasmodium, including:
- compact trophozoites with sturdy cytoplasm (Figure D)
- round to oval gametocytes that almost filled the RBCs (Figures A, C, and F)
- immature schizonts (Figures B and E). Immature schizonts are often not helpful for making a diagnosis because the merozoites are not fully developed and therefore cannot be counted. The size of the RBC can still be taken into consideration.