protozoon /prō′təzō″ən/ pl. protozoa [Gk, protos + zoon, animal] , a unicellular protist that ingests food. Protozoa include free-living forms, such as amebas and paramecia, as well as parasites. Approximately 30 protozoa are pathogenic to humans, including Plasmodium, which causes malaria, and Trypanosoma, which causes sleeping sickness. See also mastigophora.
