Most virulent is P. falciparum. Female Anopheles mosquitoes which feed on blood introduce the sporozoites in the blood. After 30 min they migrate to the liver and infect hepatocytes. Multiply, release merozoites in about 1 wk. The merozoites infect RBC, replicate, differentiate, and the cell ruptures.
New merozoites infect other RBCs.
Finally some differentiate into female and male gametocytes which are ingested by the mosquito. In the gut of the mosquito they fuse to form a zygote, multiply and differentiate into sporozoites within the salivary gland. Blockage of the capillaries, intense headaches, renal and heart failure, cerebral damage. No successful vaccine. For example T. brucei has more than 1000 VSG genes, and a single gene is expressed at any given time.