Balantidium

Balantidium [‚bal·ən′tid·ē·əm]

(invertebrate zoology)

A genus of protozoans in the order Trichostomatida containing the only ciliated protozoan species parasitic in humans,Balantidium coli.

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Balantidium 

(Balantidium coli), a protozoan from the order of uniformly ciliated infusorians.

Balantidium is a parasite in man and swine. It was first discovered in swine in 1862 by the German protozoologists R. Leuckart and F. Stein. The asymmetrical oval body of the Balantidium (30–150 microns [μm] long and 20–110 μm wide) is covered with short cilia arranged in longitudinal rows. Balantidium reproduces by transverse division. It parasitizes the large intestine, especially the cecum. It feeds on starch and food residues in the feces and elements of the blood. Sometimes Balantidia attack each other. In the intestine, Balantidia are surrounded and covered with a thick membrane, forming cysts that are excreted with the host’s feces. Balantidia may cause the disease called balantidiasis.