Rev: 09/23/2022

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Trichuris Roederer, 1761
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Morphology and Anatomy:

Stichosomes occur in two orders of the Nematoda: Trichinellida, with at least six families, and Mermithida, with two families. Recent phylogenetic analysis based on a synthesis of molecular and morphological data suggest that the stichosome may be an example of parallel evolution in the Trichinellida and Mermithida (De Ley and Blaxter, 2002; Ferris, 2007).

The pharynx is narrow and thin-walled anteriorly and which, posteriorly, is surrounded by unicellular, glandular stichocytes, each with a duct into the pharyngeal lumen.

The pharynx extends one-fourth to nine-tenths of the body length in various taxa and is almost devoid of musculature. The region of the pharynx surrounded by stichocytes is
known as the stichosome.

  A portion of the stichosome of the whipworm, Trichuris trichiura.
Photomicrograph by Sung-Jong Hong (The Korean Society for Parasitology).

Body size range for the species of this genus in the database - Click:

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Economic Importance:

Contact with soil contaminated with eggs or larvae of nematode parasites is a common form of transmission that results in human infection. The nematodes can live for years as adults in the human intestinal tract. Soil becomes contaminated by fecal material of infected humans and other animal hosts.

More than a billion people are infected with at least one species.  The most important nematode infections of the human gastrointestinal tract are the intestinal roundworm (Ascaris lumbricoides), whipworm (Trichuris trichiura), and hookworm (Necator americanus or Ancylostoma duodenale).

It is common for a single individual, especially a child living in a less developed country, to be chronically infected with all three of the nematode parasites, which results in malnutrition, stunted growth stunting, retarded intellectual development, and cognitive and educational deficiencies.


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Life Cycle:

Adult hookworms (Ancylostoma duodenale and Necator americanus) parasitize the upper part of the human small intestine, whereas Ascaris lumbricoides parasitize the entire small intestine and adult Trichuris trichiura live in the large intestine, especially the caecum

The parasites can live for several years in the human gastrointestinal tract. After mating, each adult female produces thousands of eggs per day which leave the body in the feces.

For Ecophysiological Parameters for this genus, click 


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Bethony, J., Brooker, S., Albonico, M., Geiger, S.M., Loukas, A., Diemert, D., Hotez, P.J.  2006. Soil-transmitted helminth infections: ascariasis, trichuriasis, and hookworm. The Lancet 9521:1521-1532.

Chitwood, B.G. 1930. The structure of the esophagus in the Trichuroidea. Journal of Parasitology 17:35-42.

De Ley, P. and Blaxter, M. 2002. Systematic position and phylogeny. Pp 1-30 in Lee, D.L. (ed.). The Biology of Nematodes. Taylor and Francis, London and NY. 635p.

Lee, D.L. 2002. Life cycles. Pp 61-72 in Lee, D.L. (ed.). The Biology of Nematodes.Taylor and Francis, London and NY. 635p.

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