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DPDx

DPDx is an education resource designed for health professionals and laboratory scientists. For an overview including prevention and control visit www.cdc.gov/parasites/balantidium.

Balantidiasis

[Balantidium coli]

Balantidium coli cysts in a wet mount, unstained.

B. coli cysts in a wet mount, unstained.


Balantidium coli trophozoite in a wet mount, 500× magnification. Note the visible cilia on the cell surface.

B. coli trophozoite in a wet mount, 500× magnification. Note the visible cilia on the cell surface.


Balantidium coli trophozoites in colon tissue stained with hematoxylin and eosin (H&E) at 400x magnification.

Balantidium coli trophozoites in colon tissue stained with hematoxylin and eosin (H&E) at 400x magnification.

Causal Agents

Balantidium coli, a large ciliated protozoan parasite.


Life Cycle

Life cycle of balantidiasis

Cysts are the parasite stage responsible for transmission of balantidiasis The number 1. The host most often acquires the cyst through ingestion of contaminated food or water The number 2. Following ingestion, excystation occurs in the small intestine, and the trophozoites colonize the large intestine The number 3. The trophozoites reside in the lumen of the large intestine of humans and animals, where they replicate by binary fission, during which conjugation may occur The number 4. Trophozoites undergo encystation to produce infective cysts The number 5. Some trophozoites invade the wall of the colon and multiply. Some return to the lumen and disintegrate. Mature cysts are passed with feces. The number 1

Geographic Distribution

Worldwide. Because pigs are an animal reservoir, human infections occur more frequently in areas where pigs are raised. Other potential animal reservoirs include rodents and nonhuman primates.

Clinical Presentation

Most cases are asymptomatic. Clinical manifestations, when present, include persistent diarrhea, occasionally dysentery, abdominal pain, and weight loss. Symptoms can be severe in debilitated persons.

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  • Page last reviewed November 29, 2013
  • Page last updated November 29, 2013
  • Content source: Global Health - Division of Parasitic Diseases and Malaria
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