Balantidium coli

Name

Greek: balantion = small sack; kolon = terminal portion of intestine.

Geographic Distribution

Worldwide, mainly in porcines, rarely also in humans (less than 1,000 proven cases per year).

Biology/Morphology

B. colireach a size of 50–150 μm and live in the caeca and in the colon of their hosts. This parasite belongs to the trichosomastid ciliates (Ciliophora) and is characterized by an anterior vestibulum, a cytostome-cytopharyngeal complex, several contractile vacuoles, a small/spherical micronucleus, a large macronucleus, and the lack of typical mitochondria. The surface is covered by typical cilia in regular rows which allow a significant mobility in the intestinal fluid. Reproduction occurs by binary cross-directed division, while sexual processes are involved during the rarely seen so-called conjugation, during which wandering nuclei are exchanged via a cytoplasmic bridge being formed for a short time between two trophozoites. It was noted that some trophozoites may enter...