Apicomplexa

(ap″ĭ-kŏm-plek′să)

A phylum of the kingdom Protista (formerly a division of protozoa called Sporozoa); named for a complex of cell organelles (apical microtubule complex) at the apex of the sporozoite form that can penetrate host cells. It includes the medically important genera Plasmodium, Toxoplasma, Cryptosporidium, and Isospora.