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Whipworm

Whipworm, or Trichuris trichiura, is a roundworm of the phylum nematoda that causes trichuriasis. Humans are its only known host. It derives its name from its distinct long, whip-like shape. About two-thirds of the worm is thin, with the last third being fatter, giving it an appearance resembling the handle of a whip. The head of the whipworm needs to be narrow so that it can easily burrow through the tissue of the intestine while the larger tail end ensures that the worm can still produce many eggs.

The adult worm usually grows to about 3 to 5 cm in length and lives for about 1 to 3 years. It is only commonly found in areas of the world with a dense population, a tropical climate and poor levels of sanitation, especially with regards to the disposal of human waste. Whipworm is not prevalent in the US, Western Europe, Japan or Australasia. It is far more commonly found in Southeast Asia, the Caribbean, Africa, Central and South America where prevalence rates can be as high as 80%. In these areas whipworms affect a large percentage of the population, although the symptoms of the human host are commonly mistaken for other conditions.

The whipworm's barrel-shaped eggs develop outside the body. Moist, warm, shaded soil, or sandy, coastal regions provide will a favourable environment for the eggs. The eggs will incubate and produce mature (embryonated), infective eggs in approximately 15 to 30 days. After maturation an egg can remain active for several months in suitable conditions. The eggs will not survive in direct sunlight for more than 12 hours or at extreme temperatures, less than minus 8 degrees Celsius or more than 40 degrees Celsius, for more than about an hour.

An infection occurs when mature eggs, which have been passed in faeces unembryonated into the soil, are accidentally swallowed through contact with contaminated hands or by food or drink. This is referred to as the faecal-oral route of infection. The larvae hatch in the small intestine, penetrating the mucosa and maturing. After about one week they migrate to the proximal colon and large intestine. Once there, they once again penetrate the intestine mucosa and attach themselves to the intestinal wall, their anterior portions having become threaded into the mucosa. The worms moult at points along their migration until the adult worms in the intestine are fifth-stage nematodes.

Once the worms mature sexually they will mate, with egg production occurring approximately 2 to 3 months after they were initially ingested. A female Whipworm can produce anywhere from 3,000 to 20,000 eggs in a day.

Whipworms can infest both adults and children. Whipworm infections are most common amongst children, especially who have been playing in soil containing mature whipworm eggs and have not yet developed good hygiene habits. Severe infections in young children can result in Trichuris dysentery syndrome. This constitutes bloodied mucoid diarrhoea, tenesmus (painful straining), anaemia and retarded growth. The worms feed on our tissue and it has been estimated that each worm will cause an estimated loss of about 5mcl of blood every day. Children who are heavily infected may also experience intestinal blockage due to the large number of worms.

Whipworms are asymptomatic and there are commonly no symptoms unless it is a heavy infection. A light infection, of less than 100 worms, may cause flatulence, lower abdominal pain, constipation or diarrhoea. If the infection is severe then the host may experience weight loss or anorexia, intermittent lower or epigastric pain, nausea, bloody or mucus-covered stools and diarrhoea. Other symptoms of a whipworm infection may include gastrointestinal and hematologic complications, anaemia, a lack of concentration, and fatigue. The burrowing of the whipworms can cause a severe irritation, which in particularly bad cases, may lead to rectal prolapse, which is the protrusion of the rectum out through the anus. In severe and prolonged infestations impaired physical or mental development in children can result but these are most likely to be multifactoral, incorporating vitamin deficiencies and malnutrition caused by the abnormal functioning of the intestine. Because the worms live a long time, with the constant risk of reinfection, a human can become host to a very large number of worms, numbering in the hundreds of thousands.

If you suspect that you have whipworm then you should consult a medical practitioner for diagnosis. They can diagnose an infection by examining stool samples for barrel-shaped whipworm eggs. It would also help if you can tell the doctor if you have travelled to area with a higher prevalence of whipworm. On rare occasions a whipworm may become noticed after crawling up into the throat and exiting through the nose or mouth. Polyparasitic infections that include roundworms (Ascaris lumbricoides) or hookworms can occur because all of these parasites are found in similar environments.

Whipworms can be treated with Vermox or Combantrin-1, which contain mebendazole.