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Malaria overview

Published: July 17, 2009. Updated: August 09, 2009

Malaria is a disease caused by a protozoal infection with the organism (plasmodium).

The disease course passes through 2 stages:

  • Preerythrocytic (liver) stage: sporozoites (the infective stage) form micromerozoites which can infect blood.
  • Erythrocytic stage: The red cells become infected with micromerozoites which mature within the red cells into merozoites form trophozoites (ring form). This results in rupture of the red cells and the release of merozoites in the circulation. The erythrocytic phase may continue for a long period allowing a few merozoites to develop into the sexual form of the parasite known as the gametocytes. At this stage the patient is infective. A mosquito may act as a carrier transmitting infection of sporozoites from one person to another.

Clinical manifestations

Malaria is characterized by a series of chills, fever, sweating. Tertian (3rd day) / quartan (4th day) fever.

Hepato-splenomegaly (enlargement of the liver and spleen).


Exoerythrocytic (in all types except falciparum): some merozoites don't invade RBCs but enter the liver again.


Malaria blood smears given at 6 to 12 hour intervals confirm the diagnosis.


According to the CDC, travelers going to South America, Africa, the Indian subcontinent, Asia, and the South Pacific should take one of the following drugs: mefloquine, doxycycline, chloroquine, hydroxychloroquine, or Malarone.

  • The adult dose of chloroquine is phosphate 500 mg once a week.
  • Take the first dose of chloroquine 1 week before arrival in the malaria-risk area.
  • Take your dose once a week, on the same day of the week, while in the risk area.
  • Take your dose once a week for 4 weeks after leaving the risk area.
  • Chloroquine should be taken on a full stomach to lessen the risk of nausea and stomach upset.

Malaria, especially Falciparum malaria, is a medical emergency requiring hospitalization. Chloroquine is the most frequently used anti-malarial medication, but quinidine or quinine, or the combination of pyrimethamine and sulfadoxine, are given for chloroquine-resistant infections.

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