Malaria is a disease that affects hundreds of millions of people worldwide. In the developing world malaria contributes to a high infant mortality rate and a heavy loss of work time. Malaria is caused by the single-celled protozoan parasite, Plasmodium. The disease follows two main courses: tertian (three day) malaria and quartan (four day) malaria. Plasmodium vivax causes benign tertian malaria with a low mortality (5%), while Plasmodium falciparum causes malignant tertian malaria with a high mortality (25%) due to interference with the blood supply to the brain (cerebral malaria). Quartan malaria is rarely fatal.

Plasmodium is transmitted from one human host to another by female mosquitoes of the genus Anopheles. Thousands of parasites in the salivary glands of the mosquito are injected into the human host when the mosquito takes blood. The parasites (in the sporozoite stage) are carried to the host's liver where they undergo massive multiplication into...