Case #302 – June, 2011

A 42-year-old man presented to his health care provider with fever, chills, and mild myalgia. He mentioned that his occupation requires frequent travel to Indonesia and Malaysia and that he often does not take any malaria prophylaxis. Blood smears were ordered, stained with Giemsa, and examined. Figures A–D show what was observed on thick smears at 1000x magnification with oil. Figures E–I show what was observed on thin smears at 1000x magnification with oil. 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 malariae. Diagnostic morphologic features included:

compact gametocytes with coarse pigment in red blood cells normal-sized or smaller (Figure E).
a band-form trophozoite (Figure F) consistent with P. malariae.
basket-form trophozoites (Figures G and H) consistent with P. malariae in smaller than normal red blood cells.
an immature schizont (Figure I) in an normal-sized red blood cell.