Whipworm infection

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aravind Kuchkuntla, M.B.B.S[2]

Trichuris trichiura is the third most common nematode worldwide, following Ascaris and Enterobius infections. Infection is acquired by the ingestion of embryonated eggs from contaminated drinking water and food. Whipworm causes disease by colonic mucosal invasion by the adult worm, resulting in inflammation of the colonic mucosa. In most cases, whipworm infection causes no clinical symptoms, but a severe infection can cause abdominal pain, diarrhea, constipation, weight loss, and anemia. The diagnosis of whip worm infection is confirmed by a stool examination for ova and parasites, which may demonstrate the presence of whipworm eggs. Whip worm eggs are barrel-like with two polar plugs. Medical therapy with antihelminthic medications is the primary modality of treatment, using albendazole, mebendazole, and ivermectin. Primary prevention measures include maintaining proper hygiene, hand washing, encouraging people not to defecate outdoors, and improving sewage disposal systems.

In 1761, Roederer described whipworm for the first time. In 1771, Carl Linnaeus coined the binomial name for human whipworm as Trichuris trichiura. The human whipworm (Trichuris trichiura) is generally considered “heirloom,” since it is found in African non-human primates, and parasite eggs were found in fossilized human feces in archaeological sites before animal domestication and before the Columbian colonization. The origin of human Trichuris is believed to be in Africa, where the parasite was transmitted to humans through early primates.

Trichuriasis infection is classified by the World Health Organization (WHO) for helminth control programs based on the number of eggs per gram of feces into light, moderate, and heavy infection.

Infection is acquired by the ingestion of embryonated eggs from contaminated drinking water and food. The eggs, once ingested, hatch in the small intestine, and the larvae enter the intestinal crypts. The larve migrate to the proximal colon and mature into adult worms. The females begin to oviposit 60 to 70 days after infection and shed between 3,000 and 20,000 eggs per day. Whipworm causes disease by colonic mucosal invasion of the adult worms, resulting in inflammation of the colonic mucosa.

The human whipworm (Trichuris trichiura or Trichocephalus trichiuris) is a round worm that causes trichuriasis. 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.

Trichuris trichiura must be differentiated from other nematode infections, such as ascariasis, hook worm infection, and Strongyloides stercoralis, that can present with diarrhea and abdominal pain.

Trichuris trichiura is the third most common nematode worldwide following Ascaris and Enterobius; in total, the three infections affect approximately 1 billion people. Whip worm infection is endemic in tropical and subtropical countries. The prevalence of Trichuris trichiura is high, affecting 95% of children in countries where protein energy malnutrition and anemias are prevalent.

Risk factors predisposing patients to the development of whip worm infection include low socio-economic status, low levels of education, poor sanitation, and poor hygiene.

There is insufficient evidence to recommend routine screening for Whipworm infection.

In most cases, whipworm infection causes no clinical symptoms. A heavy whipworm infection (greater than 10,000 eggs per gram of feces) infection can cause abdominal pain, diarrhea, constipation, weight loss, and anemia. If left untreated, severe infection can result in Trichuris dysentery syndrome. Complications of heavy whipworm infection include chronic dysentry, rectal prolapse, and growth retardation. Prognosis is excellent with antihelminthic treatment and complete recovery occurs in 1 to 2 weeks.

The majority of patients with light trichuriasis infection are asymptomatic. Trichuriasis presents with weight loss, bloody diarrhea, abdominal pain, tenesmus, and rectal prolapse in patients with moderate to heavy infection.

There are no specific physical examination findings associated with whip worm infection. Patients with severe infection may present with pallor, finger nail clubbing, rectal prolapse, and abdominal tenderness.

The diagnosis of whip worm infection is confirmed by a stool examination for ova and parasites. It will demonstrate the presence of whipworm eggs. There are no specific laboratory findings associated with whip worm infection. Chronic blood loss may demonstrate an iron deficiency anemia on peripheral blood smear with microcytic and hypochromic anemia.

There are no specific EKG findings associated with whipworm infection.

There are no specific chest X-Ray findings associated with whipworm infection.

CT scan findings are non specific in patients with whipworm infection, but irregular nodular colonic thickening of the cecum and the ascending colon may be present.

A double contrast barium enema will demonstrate the presence of multiple tiny target-like or pinwheel shaped collections of barium, associated with s-shaped filling defects and appearance characteristic of a male worm with a coiled tip.

The other diagnostic studies for whip worm infection include stool examination for ova and parasites, colonoscopy, and an abdominal ultrasound. Whip worm eggs are barrel-like with two polar plugs. Colonoscopy is not routinely indicated, but it can be performed in patients with non specific symptoms and a negative stool test for the presence of eggs.

Medical therapy with antihelminthic medications is the primary modality of treatment. The treatment options include albendazole, mebendazole, and ivermectin.

Surgery is not recommended for the treatment of whipworm infection.

Primary prevention measures include maintaining proper hygiene, hand washing, encouraging people not to defecate outdoors, and improving sewage disposal systems.

Secondary preventive measures for whip worm infection are similar to the primary preventive measures.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aravind Kuchkuntla, M.B.B.S[2], Syed Hassan A. Kazmi BSc, MD [3]

In 1761, Roederer described whipworm for the first time. In 1771, Carl Linnaeus coined the binomial name for human whipworm as Trichuris trichiura. The human whipworm (Trichuris trichiura) is generally considered “heirloom,” since it is found in African non-human primates, and parasite eggs were found in fossilized human feces in archaeological sites before animal domestication and before the Columbian colonization. The origin of human Trichuris is believed to be in Africa, where the parasite was transmitted to humans through early primates.

Whipworm and Humans: An evolutionary perspective

• Since the evolution of humans and the genus Homo, for the past four million years, there has been continuous contact between humans and many parasites.
• Parasites infecting humans today have different evolutionary origins and can be broadly divided into two groups:
  • Parasites transmitted to humans through primates, which are referred to as “heirloom.”
  • Parasites acquired more recently through contact with animals (e.g. during animal domestication in the Neolithic period roughly 10,000 years ago), which are referred to as “souvenirs.”^[1]
• The human whipworm (Trichuris trichiura) is generally considered “heirloom,” since it is found in African, non-human primates, and parasite eggs were found in human fossilized feces in archaeological sites before animal domestication and before the Columbian colonization.^[2]

Demographic History

• Discovery of whipworm in different parts of the world may be explained by human migrations to various parts of the world.^[3]
• The origin of human Trichuris is believed to be in Africa, where the parasite was transmitted to humans through early primates. When pigs evolved in China, they presumably acquired whipworms.^[4][5]
• Phylogenetic analysis shows that the human whipworm clustered into separate clades demographically. The first divergence for human T. trichiura occurred between the Ugandan and China/Ecuador populations (over 500,000 generations ago). Then, a second split between the China and Ecuador populations (120,000 generations) occurred. This again supports the theory of T. trichiura originating in Africa and spreading to Asia and South America by human activity.

Discovery and Binomial Nomenclature

• In 1761, Roederer described whipworm for the first time.^[6]
• In 1771, Carl Linnaeus coined the binomial name for human whipworm as Trichuris trichiura.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aravind Kuchkuntla, M.B.B.S[2]

Trichuriasis infection is classified by the World Health Organization (WHO) for helminth control programs based on the number of eggs per gram of feces into light, moderate, and heavy infection.

Trichuriasis infection is classified by the WHO for helminth control programs based on the number of eggs per gram of feces: ^[1]

• Light infection: 1-999 eggs per gram of feces
• Moderate infection: 1000 – 9999 eggs per gram of feces
• Heavy infection: Greater than 10,000 eggs per gram of feces

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Usama Talib, BSc, MD [2], Syed Hassan A. Kazmi BSc, MD [3]

Infection is acquired by the ingestion of embryonated eggs from contaminated drinking water and food. The eggs, once ingested, hatch in the small intestine, and the larvae enter the intestinal crypts. The larve migrate to the proximal colon and mature into adult worms. The females begin to oviposit 60 to 70 days after infection and shed between 3,000 and 20,000 eggs per day. Whipworm causes disease by colonic mucosal invasion of the adult worms, resulting in inflammation of the colonic mucosa.

1. The eggs develop into a two-cell stage.

2. The two-cell stage then leads to an advanced cleavage stage.

3. The eggs embryonate.

4. Eggs become infective in 15 to 30 days.

5. Mature adult worms travel in the colon.

6. The adult worms (approximately 4 cm in length) live in the cecum and ascending colon. The life span of the adult worm is approximately 1 year.

• Whipworm infection is acquired by the ingestion of embryonated eggs from contaminated drinking water and food.

• The eggs, once ingested, hatch in the small intestine, and the larvae enter the intestinal crypts.^[1][2]
• The larvae migrate to the proximal colon and mature into adult worms.
• The adult worms live in the cecum and ascending colon and attach themselves to the colonic mucosa with their anterior portions threaded into the mucosa.
• The females begin to oviposit 60 to 70 days after infection and shed between 3,000 and 20,000 eggs per day.
• Whipworm causes disease by colonic mucosal invasion of the adult worms, resulting in inflammation of the colonic mucosa.^[3]

• Whipworm infection leads to a predominantly T helper cell 2 (Th2) type immune response, which is an antibody-based immune response.^[7]

• Whipworm infection induces the production of cytokines (interleukin-4, interleukin-5, interleukin-10, and interleukin-13), parasite-specific immunoglobulin, and IgE.^[8]
• This leads to stimulation and proliferation of mast cells, eosinophils, and basophils, which play effector roles during the infection.

• Whipworm infection may present in combination with Ascaris lumbricoides, Necator americanus, and Entamoeba histolytica infections.^[9]
• Whipworm infection can also exacerbate colitis caused by infection with Campylobacter jejuni.^[10]

• Whipworm infection in humans can lead to rectal prolapse which may be visible grossly.^[11]

• Microscopy of the colonic mucosal biopsy from the affected site will demonstrate infiltration by eosinophils and neutrophils.^[12]
• Hematoxylin and eosin (H&E) stain of an infected colon may show one end of the worm embedded in the hyperemic mucosa and other end freely movable within the lumen.^[13]

• A stool examination for ova and parasites reveals the presence of whipworm eggs.
• The diagnostic characteristics are:^[14]
  • A typical barrel shape
  • Two polar plugs that are unstained
  • Size: 50 to 54 µm by 22 to 23 µm
  • The external layer of the shell of the egg is yellow-brown (in contrast to the clear polar plugs).

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

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.^[1] 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.^[2] 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 cecum 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.^[3] 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.

Infection occurs through ingestion of eggs and is more common in warmer areas. Whipworms eggs are passed in the feces of infected persons, and if an infected person defecates outside or if untreated human feces as used as fertilizer, eggs are deposited on soil where they can mature into an infective stage. Ingestion of these eggs “can happen when hands or fingers that have contaminated dirt on them are put in the mouth or by consuming vegetables or fruits that have not been carefully cooked, washed or peeled.”^[4] The eggs hatch in the small intestine, and then move into the wall of the small intestine and develop. On reaching adulthood, the thinner end (the front of the worm) burrows into the large intestine and the thicker end hangs into the lumen and mates with nearby worms. The females can grow to 50 mm (2 inches) long. Neither the male nor the female has much of a visible tail past the anus.^[1]

Whipworm commonly infects patients also infected with Giardia, Entamoeba histolytica, Ascaris lumbricoides, and hookworms.

There is a worldwide distribution of Trichuris trichiura, with an estimated 1 billion human infections.^[5][6][7] However, it is chiefly tropical, especially in Asia and, to a lesser degree, in Africa and South America. Within the United States, infection is rare overall but may be common in the rural Southeast, where 2.2 million people are thought to be infected. Poor hygiene is associated with trichuriasis as well as the consumption of shaded moist soil, or food that may have been fecally contaminated. Children are especially vulnerable to infection due to their high exposure risk. Eggs are infective about 2–3 weeks after they are deposited in the soil under proper conditions of warmth and moisture, hence its tropical distribution.

Whipworms develop when a dog swallows whipworm eggs, passed from an infected dog. Symptoms may include diarrhea, anemia, and dehydration. The dog whipworm (Trichuris vulpis) is commonly found in the U.S. It is hard to detect at times, because the numbers of eggs shed are low, and they are shed in waves. Centrifugation is the preferred method. There are several preventives available by prescription from a veterinarian to prevent dogs from getting whipworm.

The cat whipworm is a rare parasite. In Europe, it is represented mostly by Trichuris campanula, and in North America it is Trichuris serrata more often.^[8][9] Whipworm eggs found in cats in North America must be differentiated from lungworms, and from mouse whipworm eggs just passing through.

The hygiene hypothesis suggests that various immunological disorders that have been observed in humans only within the last 100 years, such as Crohn’s disease, or that have become more common during that period as hygienic practices have become more widespread, may result from a lack of exposure to parasitic worms (also called helminths) during childhood. The use of Trichuris suis ova (TSO, or pig whipworm eggs) by Weinstock, et al., as a therapy for treating Crohn’s disease^[10][11][12] and to a lesser extent ulcerative colitis^[13] are two examples that support this hypothesis. There is also anecdotal evidence that treatment of inflammatory bowel disease (IBD) with TSO decreases the incidence of asthma,^[14] allergy,^[15] and other inflammatory disorders. Some scientific evidence suggests that the course of multiple sclerosis may be very favorably altered by helminth infection;^[16] TSO is being studied as a treatment for this disease.^[17][18]

• Trichuris Trichiura at eMedicine
• Man finds extreme healing eating parasitic worms, By Elizabeth Cohen, CNN Senior Medical CorrespondentDecember 9, 2010
• Potential Disease Treatment: Swallow Some Worms
• Globe and Mail: Sometimes having worms is good
• BBC article mentions the Iceman had Whipworm
• Video of Live Trichuris trichiura “Whip Worm”

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aravind Kuchkuntla, M.B.B.S[2] Furqan M M. M.B.B.S[3]

Trichuriasis must be differentiated from other nematode infections, such as ascariasis, hook worm infection, and Strongyloides stercoralis, that can present with diarrhea and abdominal pain.

Trichuriasis must be differentiated from other nematode infections, such as ascariasis, hook worm infection, and Strongyloides stercoralis infection, that can present with diarrhea and abdominal pain.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aravind Kuchkuntla, M.B.B.S[2], Syed Hassan A. Kazmi BSc, MD [3]

Trichuris trichiura is the third most common nematode worldwide following Ascaris and Enterobius; in total, the three infections affect approximately 1 billion people. Whip worm infection is endemic in tropical and subtropical countries. The prevalence of Trichuris trichiura is high, affecting 95% of children in countries where protein energy malnutrition and anemia are prevalent.

• Worldwide, the total number of people infected with Trichuris trichiura in the year 2002 was 1 billion.^[1]
• In the USA, the prevalence of Trichuris trichiura is 100 per 100,000 individuals.^[2]

• Worldwide, the prevalence of Trichuris trichiura is high, affecting 95% of children in countries where protein energy malnutrition and anemia are prevalent.^[3]

• Trichuris trichiura is the third most common nematode worldwide following Ascaris and Enterobius; in total, the three infections affect approximately 1 billion people.

• Trichuris trichiura is more common among school-aged children compared to adults.^[4]

• There is no gender predilection for infection with Trichuris trichiura.

• There is no racial predilection for infection with Trichuris trichiura.

• Trichuriasis occurs in the southern United States.

• Whip worm infection is endemic in tropical and subtropical countries.^[5]
• Incidence and prevalence rates are highest in children living in sub-Saharan Africa, followed by Asia, then Latin America and the Caribbean.^[6][7]
• Worldwide, infections are more frequent in areas with tropical weather and poor sanitation practices.^[8]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aravind Kuchkuntla, M.B.B.S[2]

Risk factors predisposing patients to the development of whip worm infection include low socioeconomic status, low levels of education, poor sanitation, and poor hygiene.

The following risk factors predispose patients to whip worm infection:^[1][2]

• Low socioeconomic status^[1]
• Low levels of education
• Poor sanitation
• Close proximity to water sources
• Co-infection with A. lumbricoides and T. trichiura can occur in:
  • Students
  • Fishermen
  • Farmers

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aravind Kuchkuntla, M.B.B.S[2]

In most cases, whipworm infection causes no clinical symptoms, but a severe infection can cause abdominal pain, diarrhea, constipation, weight loss, and anemia. If left untreated, severe infection can result in Trichuris dysentery syndrome. Complications of heavy whipworm infection include chronic dysentry, rectal prolapse, and growth retardation. Prognosis is excellent with antihelminthic treatment and complete recovery occurs in 1 to 2 weeks.

In most cases, whipworm infection causes no clinical symptoms, but a severe infection can cause abdominal pain, diarrhea, constipation, weight loss, and anemia.^[1] If left untreated, severe infection can result in Trichuris dysentery syndrome, which presents with features of chronic dysentery, rectal prolapse, anemia, poor growth, and clubbing of the finger nails.^[2][3]

In patients with heavy infection, the following complications may develop:^[2][4]

• Chronic dysentery
• Rectal prolapse
• Growth retardation
• Anemia
• Malnutrition

The prognosis of trichuriasis is excellent with anti-helminthic treatment. All the patients recover completely with treatment.

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