What is the pathogenesis of malaria?

Updated: Apr 26, 2019
  • Author: Thomas E Herchline, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

After a mosquito takes a blood meal, the malarial sporozoites enter hepatocytes (liver phase) within minutes and then emerge in the bloodstream after a few weeks. These merozoites rapidly enter erythrocytes, where they develop into trophozoites and then into schizonts over a period of days (during the erythrocytic phase of the life cycle). Rupture of infected erythrocytes containing the schizont results in fever and merozoite release. The merozoites enter new red cells, and the process is repeated, resulting in a logarithmic increase in parasite burden. (See the images below.)

This micrograph illustrates the trophozoite form, This micrograph illustrates the trophozoite form, or immature-ring form, of the malarial parasite within peripheral erythrocytes. Red blood cells infected with trophozoites do not produce sequestrins and, therefore, are able to pass through the spleen.
A mature schizont within an erythrocyte. These red A mature schizont within an erythrocyte. These red blood cells (RBCs) are sequestered in the spleen when malaria proteins, called sequestrins, on the RBC surface bind to endothelial cells within that organ. Sequestrins are only on the surfaces of erythrocytes that contain the schizont form of the parasite.

Other, less common routes of Plasmodium infection are through blood transfusion and maternal-fetal transmission.


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