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

Macrogametocytes of P. vivax are round to oval and usually fill the host cell.  The infected RBC is usually noticeably larger than uninfected RBCs.  The cytoplasm is usually a darker blue and contains fine brown pigment throughout.  Schüffner's dots may be seen with proper staining.  Microgametocytes are usually the size of an uninfected RBC and have a paler blue, pink or gray cytoplasm.

Plasmodium vivax gametocytes

A

A: Gametocytes of P. vivax in thin blood smears.  Fig. 28 and 29: Nearly mature and mature macrogametocyte (female); Fig. 30: Microgametocyte (male).
Illustrations from: Coatney GR, Collins WE, Warren M, Contacos PG. The Primate Malarias. Bethesda: U.S. Department of Health, Education and Welfare; 1971.

Plasmodium vivax gametocyte in thick blood smear Plasmodium vivax gametocyte in thick blood smear
B C

B: Gametocyte (upper) and trophozoite (lower) of P. vivax in a thick blood smear.
C: Gametocyte of P. vivax in a thick blood smear.

Plasmodium vivax gametocyte in thin blood smear Plasmodium vivax gametocyte in thin blood smear
D E

D, E: Macrogametocytes of P. vivax in a thin blood smear.  Note the enlargement of the gametocytes compared to uninfected RBCs.

Plasmodium vivax gametocytes in thin blood smear Plasmodium vivax gametocyte in thin blood smear
F G

F, G: Macrogametocytes of P. vivax in thin blood smears.

 
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