Selected glossary of terms


Binary fission – asexual reproduction of Balantidium coli and other ciliated protozoa; common mode of replication inside large intestines of hosts


Cecum – the pouch formed at the termination of the small intestine and at the beginning of the large intestine; Balantidium coli are known to infect and invade this region of the large intestine


Ciliate – a phylum of protozoa characterized by cilia during at least one stage of life, two nuclei (macro and micro), and contractile vacuoles


Colitis – inflammation of the colon (large intestine)


Colon – generally, the large intestine


Conjugation – sexual reproduction mode of Balantidium coli and other ciliated protozoa; temporary cytoplasmic union with exchange of nuclear material


Cyst – the infective stage of Balantidium coli; the protozoa is round and spherical, with a tough, thick cyst wall made of 2 layers.  Cysts passed in the feces can be ingested by animals and can transmit Balantidiasis to new hosts.


Dysentery – a condition of severe diarrhea with passage of blood and/or mucus


Sigmoidoscopy – procedure for viewing the large intestine and for taking tissue biopsies; a thin, flexible, hollow instrument (sigmoidoscope) is inserted through the anus; physicians use sigmoidoscopy for inspecting, diagnosis, and photographing the large intestine; it is especially useful for diagnosing the cause of diarrhea, constipation, or abdominal pain, and for identifying early signs of intestinal cancers.  Using sigmoidoscopy, a “physician can see bleeding, inflammation, abnormal growths, and ulcers in the descending colon and rectum.”


Trophozoite – the non-infective stage of Balantidium coli; the protozoa is ovoid and tapered at the anterior end; trophozoites lack cyst walls but are motile thanks to the cilia covering their surfaces.  Balantidium coli feed and reproduce during the trophozoite stage.




The Parasite


Life Cycle


Animal Reservoirs

Clinical Presentation





Public Health Interventions


Glossary of terms

References and links