The document discusses the phylum Apicomplexa, which includes the protozoan parasites that cause malaria. It describes the key structures in their apical complex, including polar rings and organelles like rhoptries, micronemes, and micropores. It notes these structures likely aid in motility and altering the host cell membrane. The document then provides information on the four Plasmodium species that cause human malaria, their geographic distribution, life cycles, clinical manifestations, methods of diagnosis, and relapsing/recrudescent infections.