plasmodial infection of monkeys and apes, as with human malaria, transmitted chiefly by anopheline mosquitoes; several Plasmodium species are responsible, with Southeast Asia and Africa being the apparent centers of evolution; among the 20 plasmodial agents described from nonhuman primates, some resemble and induce a malarial infection similar to those caused by the four species of Plasmodium from humans, from which the agents of human malaria appear to be derived. SYN: monkey malaria.