Plasmodium malariae is a parasitic protozoan that causes malaria in humans. It is one of several species of Plasmodium parasites that infect other organisms as pathogens, also including Plasmodium falciparum and Plasmodium vivax, responsible for most malarial infection. Found worldwide, it causes a so-called "benign malaria", not nearly as dangerous as that produced by P. falciparum or P. vivax. The signs include fevers that recur at approximately three-day intervals – a quartan fever or quartan malaria – longer than the two-day (tertian) intervals of the other malarial parasite.