Diagnostic Findings [Last Modified: ]
Balantidiasis
[Balantidium coli]
Causal Agent Life Cycle Geographic Distribution Clinical Features Laboratory Diagnosis Treatment

Microscopy

Both Balantidium coli trophozoites and cysts are found in stool.  Trophozoites are characterized by: their large size (40 µm to 200 µm), the presence of cilia on the cell surface, a cytostome, and a bean shaped macronucleus which is often visible and a smaller, less conspicuous micronucleus.  Cysts are seen less frequently and range in size from 50 µm to 70 µm.  B. coli can also invade tissue.

B. coli trophozoite in a Mann's hematoxlyin stained smear B. coli trophozoite in a wet mount
A B

A: B. coli trophozoite in a Mann's hematoxylin stained smear, 500× magnification.  Note the cytosome (black arrow) and the bean shaped macronucleus.
B: B. coli trophozoite in a wet mount, 1000× magnification.  Note the visible cilia on the cell surface.  Image contributed by the Oregon Public Health Laboratory.

B. coli trophozoites in tissue B. coli cyst in a wet mount
C D

C: B. coli trophozites in tissue stained with hematoxylin and eosin.
D: B. coli cyst in a wet mount, unstained.

 
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