Trichuris trichiura

Trichuris trichiura is found throughout the world within temperate and tropical environments, but prefer the moisture of the tropics. (Roberts and Janovy, 2000; Smyth, 1994)

Known as whipworms, this species parasitizes humans and monkeys. Two conditions are needed for spreading of Trichuris trichiura: poor sanitation, and environmental conditions that are suitable for the worm's development. This includes a warm moist climate, low light, wet soil, and lots of rain. They are found all over the world within temperate and tropical climates. (Roberts and Janovy, 2000; Smyth, 1994)

Trichuris trichiura received the common name of whipworm from their distinctive body shape. Whipworms have an elongated anterior end that contains the mouth and esophogus that stretches into a thread-like point. The posterior end is more blunt and contains the anus and sex organs. Male whipworms are 30-45 mm long, females are slightly larger, measuring 35 to 50 mm. The anterior portion of the body is composed of the elongated esophagus with unicellular glands called stichtosomes lining the wall. The posterior end contains the organism's reproductive tract, each organism, both male and female have only a single gonad, yet females produce a large amount of eggs per day. In males, one spicule protrudes through a round sheath with spines for use in copulation. The anus is found at the end of the tail but no excretory organs exist, instead the worm excretes waste through diffusion with the environment by way of small pores in the skin. (Noble and Noble, 1973; Roberts and Janovy, 2000; Smyth, 1994)

The female produces about 5000 eggs per day into the lumen of the host gut. Once excreted into the environment the embryonation period is 21 days. At this point the proper environmental conditions are needed for development to proceed, otherwise the eggs are durable enough to last a few months in the outside environment. If the proper conditions are present, the eggs develop and are capable of infection if consumed. Once consumed the eggs move down the digestive tract of humans and into the small intestine. Here, the eggs hatch and the juveniles burrow into the epithelial lining and mature. It takes four molts for the worm to reach maturity from the egg. (Roberts and Janovy, 2000; Matthews, 1998; Noble and Noble, 1973; Smyth, 1994)

Whipworms are dioecious and both male and female worms have a single gonad. Males have a spiracle surrounded by a sheath with an ejaculatory duct which joins the intestine behind the terminal region of the intestine called the cloaca. The female vulva is located near the connection of the esophagus and the intestine.

Females may produce a phermomone to attract males. The male coils around a female with his curved area over the female genital pore. The gubernaculum, made of cuticle tissue, guides spicules which extend through the cloaca and anus. Males use spicules to hold the female during copulation. Nematode sperm are amoeboid-like and lack flagella. (Barnes, 1987; Matthews, 1998; Noble and Noble, 1973; Roberts and Janovy, 2000; Smyth, 1994)

Nematodes in general have papillae, setae and amphids as the main sense organs. Setae detect motion (mechanoreceptors), while amphids detect chemicals (chemoreceptors). (Barnes, 1987; Roberts and Janovy, 2000)

The worm enters humans as an egg, primarily from humans eating infected soil raw, or on unwashed or uncooked vegetables. The egg makes its way to the crypts of Lieberkuhn within the duodenum of the intestine. Here the juvenile hatches and begins to grow and tunnel towards the surface of the lumen. Once here the worm sticks its whip like anterior portion into the interior of the lumen while the posterior remains in the lining of the epithelium. Once in this position it remains as an adult, laying eggs into the gut and feeding on cellular contents and blood. (Bundy, 1998; Roberts and Janovy, 2000)

These parasites are usually not preyed on directly, but are ingested from host to host. Larval mortality is high as most of the parasites do not reach appropriate hosts.

This species parasitizes humans and monkeys.

One in five people, 902 million, are carriers of Trichuris trichiura worldwide with a one percent infection rate in the United States. The common treatment for Trichuris trichiura are the drugs Albendazol and Pyrantel and both are effective and cost efficient. Treatment can induce higher growth as well as academic achievement in children suffering from chronic infection. (Bahon, 1997; Bundy, 1998; Forrester, 1998; Roberts and Janovy, 2000; Smyth, 1994)