Balantidium coli

ciliate

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

June 18, 2026

Quick Summary

Balantidium coli is a genus of protozoans that are uniformly covered with cilia, which are short, hairlike projections used for movement and gathering food. These organisms typically live as parasites in the intestines of animals like pigs and apes.12

In rare instances, B. coli can infect humans, causing a severe disease known as balantidiosis or balantidial dysentery. This infection can lead to the formation of ulcers in the intestines. Balantidium feeds on red blood cells, cell fragments, and debris. Transmission to new hosts occurs through cysts passed in excrement, which are then ingested. Ciliates, as a group, are considered the most evolved and complex protozoans.12

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

2 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

Balantidium
…of minute, hairlike projections (cilia), Balantidium exists as a parasite in the intestines of pigs, apes, and other animals. The species B. coli can, in rare cases, infect humans and cause balantidiosis (balantidial dysentery), a relatively severe disease causing formation of intestinal ulcers. Balantidium, which feeds on red blood cells,…
Read More
…of minute, hairlike projections (cilia), Balantidium exists as a parasite in the intestines of pigs, apes, and other animals. The species B. coli can, in rare cases, infect humans and cause balantidiosis (balantidial dysentery), a relatively severe disease causing formation of intestinal ulcers. Balantidium, which feeds on red blood cells,…
Read More