27 Malaria

Michelle To and Valentin Villatoro

Appearance:

The morphology of malarial parasites seen in the red blood cell varies depending on the stage of maturation and species present.  Malaria can appear as rings, trophozoites, schizonts, and gametocytes. Ring forms appear as a pale blue ring with a pink/purple chromatin dot, and more than one may be present in a single red blood cell. Malarial parasites are most often seen intracellular to the red blood cell with various forms.1

 

Parasites can be visualized using the Giemsa stain during the screening of thin and thick smears.1

 

Note 1: Banana shaped gametocytes seen are characteristically  in Plasmodium falciparum infections.

 

Note 2: Malarial rings may be confused with platelets when the appear on top of a red blood cell. Platelets may be differentiated by a showing a slight clearing or halo around the platelet.2

 

Organisms:1

The malarial parasite is spread to humans by the female Anopheles sp. mosquito.

 

Malaria parasites:1,2

Plasmodium falciparum

Plasmodium vivax

Plasmodium ovale

Plasmodium malariae

Plasmodium knowlesi


References:

1. Keohane EM. Extrinsic defects leading to increased erythrocyte destruction – nonimmune causes. In: Rodak’s hematology clinical applications and principles. St. Louis, Missouri: Saunders; 2015. p. 394-410.

2. Rodak BF, Carr JH. Microorganisms. In: Clinical hematology atlas. 5th ed. St. Louis, Missouri: Elsevier Inc.; 2017. p. 195-202.

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A Laboratory Guide to Clinical Hematology by Michelle To and Valentin Villatoro is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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