Malaria is a parasitic disease that involves high fevers, shaking chills, flu-like symptoms, and anemia.

Quartan malaria; Falciparum malaria; Biduoterian fever; Blackwater fever; Tertian malaria; Plasmodium

Malaria is caused by a parasite that is transmitted from one human to another by the bite of infected Anopheles mosquitoes. In humans, the parasites (called sporozoites) travel to the liver, where they mature and release another form, the merozoites. These enter the bloodstream and infect the red blood cells.

The parasites multiply inside the red blood cells, which then rupture within 48 to 72 hours, infecting more red blood cells. The first symptoms usually occur 10 days to 4 weeks after infection, though they can appear as early as 8 days or as long as a year after infection. Then the symptoms occur in cycles of 48 to 72 hours.

The majority of symptoms are caused by the massive release of merozoites into the bloodstream, the anemia resulting from the destruction of the red blood cells, and the problems caused by large amounts of free hemoglobin released into circulation after red blood cells rupture.

Malaria can also be transmitted from a mother to her unborn baby (congenitally) and by blood transfusions. Malaria can be carried by mosquitoes in temperate climates, but the parasite disappears over the winter.

The disease is a major health problem in much of the tropics and subtropics. The CDC estimates that there are 300-500 million cases of malaria each year, and more than 1 million people die. It presents a major disease hazard for travelers to warm climates.

In some areas of the world, mosquitoes that carry malaria have developed resistance to insecticides. In addition, the parasites have developed resistance to some antibiotics. This has led to difficulty in controlling both the rate of infection and spread of this disease.

Falciparum malaria, one of four different types of malaria, affects a greater proportion of the red blood cells than the other types and is much more serious. It can be fatal within a few hours of the first symptoms.

Images

Malaria, microscopic view of cellular parasites

Malaria

Digestive system organs

Malaria, photomicrograph of cellular parasites

Mosquito, pupa

Mosquito, egg raft

Mosquito, adult feeding on the skin

Mosquito, larvae

Malaria, microscopic view of cellular parasites

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Malaria Symptoms

Review Date: 05/30/2009
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)