View an illustration about the life cycle of the malaria parasite.
Malaria typically produces a string of recurrent attacks, or paroxysms, each of which has three stages—chills, followed by fever, and then sweating. Along with chills, the person is likely to have headache, malaise, fatigue, muscular pains, occasional nausea, vomiting, and diarrhea. Within an hour or two, the body temperature rises, and the skin feels hot and dry. Then, as the body temperature falls, a drenching sweat begins. The person, feeling tired and weak, is likely to fall asleep.
The symptoms first appear some 10 to 16 days after the infectious mosquito bite and coincide with the bursting of infected red blood cells (RBCs). When many RBCs are infected and break at the same time, malaria attacks can recur at regular time periods—every two days for Plasmodium vivax malaria and P. ovale and every three days for P. malariae.
With P. vivax malaria, the person may feel fine between attacks. Even without treatment, the paroxysms subside in a few weeks. A person with P. falciparum malaria, however, is likely to feel miserable even between attacks and, without treatment, may die. One reason P. falciparum malaria is so virulent is that the parasite can infect RBCs in all stages of development, leading to very high parasite levels in the blood. In contrast, P. vivax parasites infect only young RBCs, which means the number of parasites in the blood does not reach the same high levels as seen in P. falciparum infection.
Last Updated February 25, 2009
Last Reviewed February 25, 2009