Malaria is a disease caused by a unicellular parasite known as Plasmodium. Although more than 100 different species of Plasmodium exist, only four types are known to infect humans including, Plasmodium falciparum, vivax, malariae, and ovale. While each type has a distinct appearance under the microscope, they each can cause a different pattern of symptoms. Plasmodium falciparum is the major cause of death in Africa, while Plasmodium vivax is the most geographically widespread of the species and the cause of most malaria cases diagnosed in the United States. Plasmodium malariae infections produce typical malaria symptoms that persist in the blood for very long periods, sometimes without ever producing symptoms. Plasmodium ovale is rare, and is isolated to West Africa. Obtaining the complete sequence of the Plasmodium genome is currently under way.

The life cycle of Plasmodium relies...