Dictionary > Balantidiasis


noun, plural: balantidiases
An infection due to the presence of Balantidium coli
Baantidiasis is an infection caused by the parasitic ciliate Balantidium coli. This ciliate has two forms in its life cycle: trophozoite and cyst. The trophozoite B. coli is regarded as the largest protozoan to infect humans. Its size is about 30 to 150 µm in length and 25 to 120 µm in width.1 It has a perceptible sausage-like macronucleus and a spherical, less prominent micronucleus when viewed under a microscope. The trophozoite has a ciliated surface. It replicates by transverse binary fission. As a parasite, the trophozoite colonizes the large intestine where it feeds on the intestinal flora. It may form into a cyst, which is released to the environment together with the feces. The cyst has a tough cyst wall by being comprised of one or more layers. It is non-motile. However, the mature cyst of B. coli is its infective stage. When a host ingests food or water contaminated with this cyst, the cyst then develops into a trophozoite when it reaches the small intestine.
The hosts are typically pigs, rats, and other mammals. Balantidiasis is a zoonotic disease; humans may become a host and may be harmed by the presence of this protozoan. One of the symptoms of balantidiasis in humans is either diarrhea or constipation. In pigs, balantidiasis does not cause harm, and, as such, is usually asymptomatic.
See also:


1 Roberts, L. S., Janovy Jr., J. Schmidt, G. D., & Roberts, L. S. (2009). Foundations of Parasitology (8th ed.). New York: McGraw-Hill.

You will also like...

Kidneys and Regulation of Water and Inorganic Ions

The kidneys are responsible for the regulation of water and inorganic ions. Read this tutorial to learn about the differ..

primitive arthropods

The arthropods were assumed to be the first taxon of species to possess jointed limbs and exoskeleton, exhibit more adva..

kinesin motor proteins transporting molecules across microtubules
Movement of Molecules Across Cell Membranes

Molecules move within the cell or from one cell to another through different strategies. Transport may be in the form of..

New Zealand Fauna
New Zealand’s Unique Fauna

Meet some of New Zealand's unique fauna, including endemic insects, frogs, reptiles, birds, and mammals, and investigate..

Still freshwater and plants
Still Freshwater & Plants

Plants in lentic habitats have features not found in terrestrial plants. They acquired these features as they adapt to t..

Freshwater Ecology
Freshwater Ecology

Freshwater ecology focuses on the relations of aquatic organisms to their freshwater habitats. There are two forms of co..