结肠小袋纤毛虫为人体最大的寄生原虫,体长50～80微米,宽30～60微米。包囊则较小。其滋养体周身被短细纤毛,不断摆动。受染者约1/5人可以得病。原虫寄生于人或动物的结肠内,其侵害肠组织的病理改变与阿米巴痢疾相似,但程度较轻,结肠粘膜可发生溃疡。临床症状亦与急、慢性痢疾 Colonic pouch ciliates the largest parasitic protozoan, body length 50 ~ 80 microns, width 30 ~ 60 microns. Encapsulation is smaller. The body of its trophozoites are short cilia, constantly swinging. About 1/5 of affected people can get sick. Protozoan parasites in human or animal colon, the invasion of intestinal tissue pathological changes and amoebic dysentery is similar, but to a lesser extent, colon mucosa ulcers may occur. Clinical symptoms are also acute and chronic dysentery