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Trichuris trichiura
The human whipworm (''Trichuris trichiura or Trichocephalus trichiuris'') is a round worm (a type of helminth) that causes trichuriasis (a type of helminthiasis which is one of the neglected tropical diseases) when it infects a human large intestine. It is commonly known as the ''whipworm'' which refers to the shape of the worm; it looks like a whip with wider "handles" at the posterior end.
== Life cycle ==
The female ''T. trichiura'' produces 2,000–10,000 single-celled eggs per day. Eggs are deposited from human feces to soil where, after two to three weeks, they become embryonated and enter the “infective” stage. These embryonated infective eggs are ingested and hatch in the human small intestine exploiting the intestinal microflora as hatching stimulus. This is the location of growth and molting. The infective larvae penetrate the villi and continue to develop in the small intestine. The young worms move to the ceacum and penetrate the mucosa and there they complete development to adult worms in the large intestine. The life cycle from time of ingestion of eggs to development of mature worms takes approximately three months. During this time, there may be limited signs of infection in stool samples due to lack of egg production and shedding. The female ''T. trichiura'' begin to lay eggs after three months of maturity. Worms can live up to five years, during which time females can lay up to 20,000 eggs per day.
Recent studies using genome-wide scan revealed two quantitative trait loci on chromosome 9 and chromosome 18 may be responsible for genetic predisposition or susceptibility to infection of ''T. trichiura'' by some individuals.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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