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Balantidium coli has two developmental stages, a trophozoite stage and a cyst stage. In trophozoites, the two nuclei are visible. In trophozoites, the two nuclei are visible. The macronucleus is long and sausage-shaped, and the spherical micronucleus is nested next to it, often hidden by the macronucleus.
Balantidium coli exists in either of two developmental stages: trophozoites and cysts. [3] In the trophozoite form, they can be oblong or spherical, and are typically 30 to 150 μm in length and 25 to 120 μm in width. [4] It is its size at this stage that allows Balantidium coli to be characterized as the largest protozoan parasite of humans. [3]
The Balantidium coli species has a worldwide distribution, but is more frequent in subtropical and temperate climates. The medical condition balantidiasis is particularly prevalent where poor hygiene and undernourishment weaken a population coincide with living in close contact with pigs, the main reservoir for the species.
Balantidium coli is one of the species that has been reclassified. It has also been proposed that it is a junior synonym of genus Balantioides–which has B. coli as the type species. [6] The closest known relative of this genus is Buxtonella sulcata, a parasite of cattle.
These include the species Balantidium coli, which is the only ciliate parasitic in humans. The group Rhynchostomatia includes two free-living orders previously included among the Haptoria, but now known to be genetically distinct from them, the Dileptida and the Tracheliida. [2] [3]
The only member of the ciliate phylum known to be pathogenic to humans is Balantidium coli, [36] which causes the disease balantidiasis. It is not pathogenic to the domestic pig, the primary reservoir of this pathogen.
Life cycle of Balantidium coli. The Malaria lifecycle is divided into two phases: Human: The infected female mosquito (usually Anopheles species) bites a human and injects sporozoites into the bloodstream during a bloodmeal. [8] The sporozoites travel to the liver where they invade liver cells (hepatocytes) in the Exo-erythrocytic Cycle. [9]
An example is Balantidium coli, a ciliate. In other protozoa, and in cells from multicellular organisms, phagocytosis takes place at any point on the cell or feeding takes place by absorption. In other protozoa, and in cells from multicellular organisms, phagocytosis takes place at any point on the cell or feeding takes place by absorption.