Four species of protozoan parasites of the genus Plasmodium are responsible for causing malaria in humans. These are P. falciparum, P.vivax, P. ovale, and P. malariae. Most of malaria infections in the world are caused by P. vivax. However, the most severe form of malaria is caused by P. falcifarum which is prevalent in Africa. A malaria infection does not necessarily result in a disease.
Some infected persons develop immunity to the disease.
Furthermore, when a disease does occur, its severity depends upon the infected person's immunity status. Other factors that affect the severity of the disease are the infected person's age and genetic makeup. Classic symptoms of malaria are chills, intense fever, or sweats. An infection caused by P. falciparum is a medical emergency that may result in death. P. falciparum often causes cerebral malaria, which may induce coma.