Malaria, infectious parasitic disease that can be either acute or chronic and is frequently recurrent. Malaria is common in Africa, Central and South America, the Mediterranean countries, Asia, and many of the Pacific islands.
In the United States it was found in the South and less frequently in the northern and western parts of the country.
The primary causative organism, Plasmodium falciparum, requires both the Anopheles mosquito and humans to complete its life cycle: sexual reproduction of the protozoan occurs in the mosquito; an immature form is then transmitted to the human via the bite of the mosquito.
In a person the parasite goes to the liver, replicates, and moves into the bloodstream, where it attacks red blood cells for their hemoglobin. Some of the plasmodia become sexually mature and are transmitted back to another biting mosquito. Three other Plasmodium species also infect humans.