protozoa

Plural of protozoan.

A phylum comprising the unicellular eukaryotic organisms; most are freeliving, but some lead commensalistic, mutualistic, saprophytic or parasitic existences. Subphyla of veterinary interest include: (1) Sarcodina—including coccidia, cryptosporidia, Toxoplasma, Babesia, Plasmodium and others; (2) Mastigophora—including trypanosomes, Histomonas, Trichomonas spp.
Pathogenic protozoa for animals include: Acanthamoeba, Babesia, Balantidium, Besnoitia, Chilomastix, Cochlosoma, Cryptobia, Cryptosporidium, Cystoisospora, Dientamoeba, Eimeria, Encephalitozoon, Endolimax, Entamoeba, Frenkelia, Giardia, Haemoproteus, Hammondia, Hartmannella, Hepatozoon, Hexamita, Histomonas, Iodamoeba, Isospora, Klossiella, Leishmania, Leucocytozoon, Naegleria, Parahistomonas, Pentatrichomonas, Plasmodium, Sarcocystis, Theileria, Toxoplasma, Trichomonas, Tritrichomonas, Trypanosoma, Tyzzeria and Wenyonella spp.