Malaria is caused by a parasite that is passed from one human to another by the bite of infected Anopheles mosquitoes. After infection, the parasites travel through the bloodstream to the liver, where they mature and release another form, the merozoites. The parasites enter the bloodstream and infect red blood cells. The parasites multiply inside the red blood cells, which then break open within 48 to 72 hours, infecting more red blood cells.

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. 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. These conditions have led to difficulty in controlling both the rate of infection and spread of this disease.

Most symptoms are caused by:

• The release of merozoites into the bloodstream
• Anemia resulting from the destruction of the red blood cells
• Large amounts of free hemoglobin being released into circulation after red blood cells break open

Symptoms

The first symptoms usually occur 10 days to four weeks after infection, though they can appear as early as eight days or as long as a year after infection. Symptoms include: anemia, bloody stools, chills, coma, convulsions, fever, headache, jaundice, muscle pain, nausea, sweating, vomiting.

Treatment

Malaria is a medical emergency that requires a hospital stay. Chloroquine is often used as an anti-malarial medication. However, chloroquine-resistant infections are common in some parts of the world.

Medical care, including fluids through a vein (IV) and other medications and breathing (respiratory) support may be needed.