Trichuris trichiura
| Whipworm(s) | |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Nematoda |
| Class: | Enoplea |
| Order: | Trichocephalida |
| Family: | Trichuridae |
| Genus: | Trichuris |
| Species: | T. trichiura |
| Binomial name | |
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Trichuris trichiura (Linnaeus, 1771) |
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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.
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 caecum 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.
Trichuris trichiura has a narrow anterior esophageal end and shorter and thicker posterior anus. These pinkish-white worms are threaded through the mucosa. They attach to the host through their slender anterior end and feed on tissue secretions instead of blood. Females are larger than males; approximately 35–50 mm long compared to 30–45 mm. The females have a bluntly round posterior end compared to their male counterparts with a coiled posterior end. Their characteristic eggs are barrel-shaped and brown, and have bipolar protuberances..
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