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Trichuris trichiura

By Robert Fraumann

Geographic Range

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)

Habitat

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)

  • Aquatic Biomes
  • temporary pools

Physical Description

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)

  • Sexual Dimorphism
  • female larger
  • sexes shaped differently
  • Range length
    30 to 50 mm
    1.18 to 1.97 in

Development

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)

Reproduction

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)

  • Parental Investment
  • pre-fertilization
    • provisioning
  • pre-hatching/birth
    • provisioning
      • female

Communication and Perception

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)

Food Habits

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)

  • Animal Foods
  • body fluids

Predation

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.

Ecosystem Roles

This species parasitizes humans and monkeys.

Species Used as Host

Economic Importance for Humans: Negative

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)

Contributors

Renee Sherman Mulcrone (editor).

Robert Fraumann (author), University of Michigan-Ann Arbor, Solomon David (editor), University of Michigan-Ann Arbor.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

causes disease in humans

an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

chemical

uses smells or other chemicals to communicate

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

freshwater

mainly lives in water that is not salty.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

internal fertilization

fertilization takes place within the female's body

marsh

marshes are wetland areas often dominated by grasses and reeds.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

ovoviviparous

reproduction in which eggs develop within the maternal body without additional nourishment from the parent and hatch within the parent or immediately after laying.

parasite

an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scrub forest

scrub forests develop in areas that experience dry seasons.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

suburban

living in residential areas on the outskirts of large cities or towns.

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

urban

living in cities and large towns, landscapes dominated by human structures and activity.

References

Bahon, J. 1997. Colonic Obstruction and Performation Related to Heavy Trichuris trichuria infestation. Journal of Clinical Pathology, 50(7): 615-616.

Barnes, R. 1987. Invertebrate Zoology. Orlando, Florida: Dryden Press.

Bundy, D. 1998. Anthemic Treatment for Infestation with Trichurida trichiura. The Lancet, 352(9144): 1935.

Forrester, J. 1998. Randomized Trial of Albendozole and Pyrantel in Symptomless Trichuriasis in Children. The Lancet, 352(9134): 1103-1108.

Matthews, B. 1998. An Introduction to Parasitology. New York: Cambridge University Press.

Noble, E., G. Noble. 1973. Parasitology: the Biology of Animal Parasites. London: Henry Kimpton Publishers.

Roberts, L., J. Janovy. 2000. Foundations of Parasitology. New York: McGraw Hill.

Smyth, J. 1994. Intorduction to Animal Parasitology. New York: Cambridge University Press.

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