Balantidium coli

Classification

Species of Ciliophora.

General Information

The ciliate Balantidium coli, 50–200 μm in length (Fig. 2, page 158) lives in the lumen of the colon of humans, pigs, rodents, and many mammals but is often invasive, forming deep ulcers with undermining margins. The balantidia are found in these ulcers and extend the ulcer base to the muscularis and occasionally beyond, leading to perforation. The inflammatory reaction is neutrophilic, but whether it is due to the ciliates or the accompanying bacteria is not known.

Figure 2

Fresh preparation of a trophozoiteof Balantidium coli of pigs. The cilia are invisible due tomovement.