U T L IF

he protozoan parasite Plasmodium infects a wide range of warm-blooded hosts and causes malaria in humans. These parasites undergo complex develop-mental changes in both a mosquito vector and host, including asexual and sexual cycles (see the figure). Asexual reproduction occurs most often in a host’s red blood cells. Multiplication eventually causes red blood cells to rupture, and although most of the released parasites invade other red blood cells, a few develop in the bloodstream into male and female game-tocytes. When ingested by a mosquito, these gametocytes mature into gametes and the sex-ual reproductive phase of the life cycle begins