Case #499 – September, 2019

A 5-year-old child was taken to a children’s hospital with presumed febrile illness (symptoms and travel history were not provided). A blood smear was made and stained with what appeared to be Wright-Giemsa. The stained slides were sent to the State Public Health Lab which submitted images to CDC/DPDx for diagnostic assistance (Figures A–H). What is your diagnosis? Based on what criteria?

The images of this case were kindly provided by the Pennsylvania Department of Health; the exact age of the patient has been edited for the purpose of this case.

Figure A

Figure B

Figure C

Figure D

Figure E

Figure F

Figure G

Figure H

This was a case of malaria caused by Plasmodium ovale. It is always preferred and helpful to have the travel history and symptoms of the patient in all cases of malaria, although the morphologic presentation of parasites shown in the images of this case was sufficient to determine the species of Plasmodium, which included:

Slightly enlarged infected red blood cells (iRBCs)
Coarse pigment associated with trophozoites, schizonts, and gametocytes
Infected RBCs that were oval and/or fimbriated (finger-like projections on one or two poles)
A schizont (Figure D) with ~8 large merozoites that numbered within the range for P. ovale (6-14) and outside the range for P. vivax (12 – 24).
A large gametocyte in an oval, fimbriated iRBC (Figure E)

More on malaria https://www.cdc.gov/dpdx/malaria/index.html

Images presented in the dpdx case studies are from specimens submitted for diagnosis or archiving. On rare occasions, clinical histories given may be partly fictitious.