Case #190 – October, 2006

The DPDx Team received a telediagnosis request asking for confirmation of an identification made by the Wisconsin State Laboratory of Hygiene. The patient had a travel history to India. Figures A and B show objects seen on the thick blood smears stained with Wright-Giemsa. Figures C-G were taken from the thin smears. What is your diagnosis? Based on what criteria?

Figure A

Figure B

Figure C

Figure D

Figure E

Figure F

Figure G

This was a case of malaria caused by Plasmodium vivax. Diagnostic features were:

sturdy rings (see Figures C and E).
an amoeboid trophozoite (Figure C).
a large gametocyte (Figure D) that almost fills the entire red blood cell. The infected cell is enlarged 1 1/2×.
free merozoites following the rupture of a schizont (Figure G).

Depending on type of stain used and pH of the stain, Schüffner’s dots (stippling) may not always be demonstrated. For information on staining blood smears, please click here.