Balantidium coli

Ciliates:
Balantidium coli:
1- Related to phylum ciliophora, class: kinetofragminophorea
2- Considered as the largest protozoan known to humans
3- Balantidium coli troph may measure from 28µm to 125µm in length. The average troph with is approximately 40µm. the ovoid to sac-shaped B. coli troph tapers at the anterior end. The organism typically exhibits rotary, boring motility. The troph contains two nuclei, the micronucleus is located adjacent to the macronucleus. The micronucleus is often no readily visible, even in stained preparations, whereas the macronucleus may often appear as a hyaline mass (kidney shape macronucleus).
Two contractile vacuoles are located in the granules cytoplasm, although sometimes only one is readily visible.
The cytoplasm may also contain food vacuoles. The toph is equipped with a small cytosome. A layer of cilia surrounds the organism, which serves as its means of locomotion.
4- Cysts are subspherical to oval, may measure from 43 to 66 µm, contain two nucleus: kidney-shaped macronucleus usually present and small, spherical micronucleus may not be observable.
One to two visible contractile vacuoles present in young cyst. A double-protective cyst wall surrounds the organism.
A row of cilia may be visible between the two cyst wall layers in unstained young cysts.
5- Lab. diagnosis of B. coli is accomplished by examining stool specimens for the presence of troph & cysts.
6- B. coli life cycle is very similar that of Ent. histolytica. Human infection is initiated upon ingestion of infective cysts in contaminated food or water. Unlike that of Ent. hstolytica multiplication of the B. coli nuclei does not occur in the cyst phase