Plasmodium parasites are the causative agents of malaria, one of the most significant infectious diseases affecting humans. These parasites are protozoans belonging to the genus Plasmodium. There are several species of Plasmodium that infect humans, including Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, and Plasmodium malariae. Plasmodium knowlesi, primarily a parasite of macaques, can also infect humans.