Diagnostic Findings [Last Modified: ]
Malaria
[Plasmodium falciparum] [Plasmodium malariae]
[Plasmodium ovale] [Plasmodium vivax]
Causal Agent Life Cycle Geographic Distribution Clinical Features Laboratory Diagnosis Treatment

Plasmodium falciparum: Ring Stage Parasites

P. falciparum ring stage

Fig. 1: Normal red cell; Figs. 2-10: Increasingly mature ring stage parasites.
Illustration from: Coatney GR, Collins WE, Warren M, Contacos PG. The Primate Malarias. Bethesda: U.S. Department of Health, Education and Welfare; 1971.

Smears from patients:

Plasmodium falciparum rings have delicate cytoplasm and 1 or 2 small chromatin dots.  Red blood cells (RBCs) that are infected are not enlarged; multiple infection of RBCs more common in P. falciparum than in other species.  Occasional appliqué forms (rings appearing on the periphery of the RBC) can be present.

P. falciparum rings - applique form - thin smear P. falciparum rings - applique form - thin smear P. falciparum rings - applique form - thin smear
A B C

A, B, C: Multiply infected red blood cells with appliqué forms in thin blood smears.

P. falciparum ring - thin smear P. falciparum ring - thin smear
D E

D: Signet ring form.
E: Double chromatin dot.

P. falciparum rings - thick smear
G

G: A thick blood smear showing many ring forms of P. falciparum.
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