Parasitic Protozoa

Single celled protozoan parasites whose defining trait is an obligate life cycle inside a host, covering the apicomplexans, kinetoplastid flagellates and other parasitic lineages that cause major human and animal diseases such as malaria, sleeping sickness, Chagas disease, leishmaniasis, giardiasis, cryptosporidiosis and trichomoniasis. Identified by their own sourced description rather than by name. Distinguished from Ciliates and Amoebae by lifestyle rather than by shape or locomotion: an amoeba or ciliate that is only an occasional, opportunistic pathogen of an otherwise free living organism stays in that subcategory, while an organism that cannot complete its life cycle outside a host belongs here.