Trichuris trichiura

Last updated

Whipworm(s)
Trichuris trichiura, male.jpg
Male
Trichuris trichiura, female.jpg
Female
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Nematoda
Class: Enoplea
Order: Trichocephalida
Family: Trichuridae
Genus: Trichuris
Species:
T. trichiura
Binomial name
Trichuris trichiura
(Linnaeus, 1771)

Trichuris trichiura, Trichocephalus trichiuris or whipworm, is a parasitic roundworm (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. [1]

Contents

Life cycle

Life cycle of Trichuris trichiura inside and outside the human body Trichuris trichiura Life Cycle.tif
Life cycle of Trichuris trichiura inside and outside the human body

The female T. trichiura produces 2,000–10,000 single-celled eggs per day. [2] 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 by hand-mouth or through fomites and hatch in the human small intestine, exploiting the intestinal microflora as a stimulus to hatching. [3] 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 as adult worms in the large intestine. The life cycle from the time of ingestion of eggs to the development of mature worms takes approximately three months. During this time, there may be limited signs of infection in stool samples, due to a lack of egg production and shedding. The female T. trichiura begin to lay eggs after three months of maturity. Worms commonly live for about one year, [4] during which time females can lay up to 20,000 eggs per day.

Trichuris trichiura is a roundworm that infects the intestines. [4] It can cause various symptoms and has been known to lead to death.[ citation needed ]Trichuris trichiura lives in the soil in its egg stage. Once it is ingested, it develops into the larvae stage, finally maturing into the adult stage in the intestines. [5]

Recent studies using genome-wide scanning revealed that two quantitative trait loci on chromosome 9 and chromosome 18 may be responsible for a genetic predisposition or susceptibility to infection of T. trichiura by some individuals.

Morphology

Cross-section of whipworm on microscopy Cross-section of whipworm on microscopy.jpg
Cross-section of whipworm on microscopy
Eggs of Trichuris trichura. Image C shows HE stain. Trichuris trichiura eggs, including HE stain.jpg
Eggs of Trichuris trichura. Image C shows HE stain.

Trichuris trichiura has a narrow anterior esophageal end and shorter and thicker posterior end. 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. [6] 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

Trichuriasis, also known as whipworm infection, occurs through ingestion of whipworm eggs and is more common in warmer climates. Whipworm eggs are passed in the feces of infected persons, and if an infected person defecates outdoors or if untreated human feces is used as fertilizer, eggs are deposited on soil where they can mature into an infective stage. [4] 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, then move into the wall of the small intestine and develop. On reaching adulthood, the thinner end (the anterior of the worm) burrows into the large intestine, the thicker (posterior) end projecting into the lumen, where it mates with nearby worms. The females can grow to 50 mm (2.0 in) long. [2]

Trichuris trichiura can cause the serious disease Trichuris dysentery syndrome (TDS), with chronic dysentery, anemia, rectal prolapse, and poor growth. [7] TDS is treated with anthelminthics as well as iron supplementation for anemia. [8]

Whipworm commonly infects patients also infected with Giardia , Entamoeba histolytica , Ascaris lumbricoides , and hookworms. [9]

Treatment

Trichuris trichiura can be treated with a single dose of albendazole. [10] In Kenya, half of a group of children who had Trichuris trichiura were given albendazole, while the other half of the children received placebos. It was found that the children who received the drug grew significantly better than the group of children who did not receive the treatment.[ citation needed ] Another treatment that can be used is mebendazole, or flubendazole. [11] The medication interferes with the parasite’s nutrient intake, which eventually leads to death.

Epidemiology

There is a worldwide distribution of Trichuris trichiura, with an estimated 1 billion human infections. [12] [13] [14] [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.

A closely related species, Trichuris suis, which typically infects pigs, is capable of infecting humans. This shows that the two species have very close evolutionary histories. However, morphology and developmental stages remain different, making them two separate species. [15]

Treatment of inflammatory disorders

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 (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 [16] [17] [18] and to a lesser extent ulcerative colitis [19] 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, [20] [ self-published source? ] allergy, [21] and other inflammatory disorders. [22] Some scientific evidence suggests that the course of multiple sclerosis may be very favorably altered by helminth infection; [23] TSO is being studied as a treatment for this disease. [24] [25]

Related Research Articles

<i>Ascaris lumbricoides</i> One of several species of Ascaris

Ascaris lumbricoides is a large parasitic worm that causes ascariasis in humans. A roundworm of genus Ascaris, it is the most common parasitic worm in humans. An estimated one-sixth of the human population is at some point infected by a roundworm such as A. lumbricoides; people living in tropical and subtropical countries are at greater risk of infection.

<span class="mw-page-title-main">Trichuriasis</span> Infection by Trichuris trichiura (whipworm)

Trichuriasis, also known as whipworm infection, is an infection by the parasitic worm Trichuris trichiura (whipworm). If infection is only with a few worms, there are often no symptoms. In those who are infected with many worms, there may be abdominal pain, fatigue and diarrhea. The diarrhea sometimes contains blood. Infections in children may cause poor intellectual and physical development. Low red blood cell levels may occur due to loss of blood.

<span class="mw-page-title-main">Ascariasis</span> Disease caused by the parasitic roundworm Ascaris lumbricoides

Ascariasis is a disease caused by the parasitic roundworm Ascaris lumbricoides. Infections have no symptoms in more than 85% of cases, especially if the number of worms is small. Symptoms increase with the number of worms present and may include shortness of breath and fever in the beginning of the disease. These may be followed by symptoms of abdominal swelling, abdominal pain, and diarrhea. Children are most commonly affected, and in this age group the infection may also cause poor weight gain, malnutrition, and learning problems.

<span class="mw-page-title-main">Helminthiasis</span> Any macroparasitic disease caused by helminths

Helminthiasis, also known as worm infection, is any macroparasitic disease of humans and other animals in which a part of the body is infected with parasitic worms, known as helminths. There are numerous species of these parasites, which are broadly classified into tapeworms, flukes, and roundworms. They often live in the gastrointestinal tract of their hosts, but they may also burrow into other organs, where they induce physiological damage.

Hymenolepiasis is infestation by one of two species of tapeworm: Hymenolepis nana or H. diminuta. Alternative names are dwarf tapeworm infection and rat tapeworm infection. The disease is a type of helminthiasis which is classified as a neglected tropical disease.

<span class="mw-page-title-main">Colitis</span> Inflammation of the colon (large intestine)

Colitis is swelling or inflammation of the large intestine (colon). Colitis may be acute and self-limited or long-term. It broadly fits into the category of digestive diseases.

<i>Necator americanus</i> Species of hookworm

Necator americanus is a species of hookworm commonly known as the New World hookworm. Like other hookworms, it is a member of the phylum Nematoda. It is an obligatory parasitic nematode that lives in the small intestine of human hosts. Necatoriasis—a type of helminthiasis—is the term for the condition of being host to an infestation of a species of Necator. Since N. americanus and Ancylostoma duodenale are the two species of hookworms that most commonly infest humans, they are usually dealt with under the collective heading of "hookworm infection". They differ most obviously in geographical distribution, structure of mouthparts, and relative size.

<i>Taenia solium</i> Species of Cestoda

Taenia solium, the pork tapeworm, belongs to the cyclophyllid cestode family Taeniidae. It is found throughout the world and is most common in countries where pork is eaten. It is a tapeworm that uses humans as its definitive host and pigs as the intermediate or secondary hosts. It is transmitted to pigs through human feces that contain the parasite eggs and contaminate their fodder. Pigs ingest the eggs, which develop into larvae, then into oncospheres, and ultimately into infective tapeworm cysts, called cysticercus. Humans acquire the cysts through consumption of uncooked or under-cooked pork and the cysts grow into an adult worms in the small intestine.

<span class="mw-page-title-main">Parasitic worm</span> Large type of parasitic organism

Parasitic worms, also known as helminths, are large macroparasites; adults can generally be seen with the naked eye. Many are intestinal worms that are soil-transmitted and infect the gastrointestinal tract. Other parasitic worms such as schistosomes reside in blood vessels.

<span class="mw-page-title-main">Helminthic therapy</span> Deliberate infestation with parasitic worms

Helminthic therapy, an experimental type of immunotherapy, is the treatment of autoimmune diseases and immune disorders by means of deliberate infestation with a helminth or with the eggs of a helminth. Helminths are parasitic worms such as hookworms, whipworms, and threadworms that have evolved to live within a host organism on which they rely for nutrients. These worms are members of two phyla: nematodes, which are primarily used in human helminthic therapy, and flat worms (trematodes).

The soil-transmitted helminths are a group of intestinal parasites belonging to the phylum Nematoda that are transmitted primarily through contaminated soil. They are so called because they have a direct life cycle which requires no intermediate hosts or vectors, and the parasitic infection occurs through faecal contamination of soil, foodstuffs and water supplies. The adult forms are essentially parasites of humans, causing soil-transmitted helminthiasis (STH), but also infect domesticated mammals. The juveniles are the infective forms and they undergo tissue-migratory stages during which they invade vital organs such as lungs and liver. Thus the disease manifestations can be both local and systemic. The geohelminths together present an enormous infection burden on humanity, amounting to 135,000 deaths every year, and persistent infection of more than two billion people.

<i>Trichuris</i> Genus of roundworms

Trichuris, often referred to as whipworms, is a genus of parasitic worms from the roundworm family Trichuridae, which are helminths. The name whipworm refers to the shape of the worm; they look like whips with wider "handles" at the posterior end. The name Trichocephalus is sometimes used for this genus.

<span class="mw-page-title-main">Ancylostomiasis</span> Medical condition

Ancylostomiasis is a hookworm disease caused by infection with Ancylostoma hookworms. The name is derived from Greek ancylos αγκύλος "crooked, bent" and stoma στόμα "mouth".

Necatoriasis is the condition of infection by Necator hookworms, such as Necator americanus. This hookworm infection is a type of helminthiasis (infection) which is a type of neglected tropical disease.

Capillaria philippinensis is a parasitic nematode which causes intestinal capillariasis. This sometimes fatal disease was first discovered in Northern Luzon, Philippines, in 1964. Cases have also been reported from China, Egypt, Indonesia, Iran, Japan, Korea, Lao PDR, Taiwan and Thailand. Cases diagnosed in Italy and Spain were believed to be acquired abroad, with one case possibly contracted in Colombia. The natural life cycle of C. philippinensis is believed to involve fish as intermediate hosts, and fish-eating birds as definitive hosts. Humans acquire C. philippinensis by eating small species of infested fish whole and raw.

<i>Trichuris suis</i> Species of roundworm

Trichuris suis is a whipworm; the variations in thickness of the anterior and posterior segments give the parasite the characteristic "whip-like" appearance. Adult females measure 6 to 8 cm and adult males 3 to 4 cm. T. suis eggs are oval and yellow-brown with bipolar plugs. T. suis is also used in helminthic therapy studies.

<i>Oesophagostomum</i> Genus of roundworms

Oesophagostomum is a genus of parasitic nematodes (roundworms) of the family Strongylidae. These worms occur in Africa, Brazil, China, Indonesia and the Philippines. The majority of human infection with Oesophagostomum is localized to northern Togo and Ghana. Because the eggs may be indistinguishable from those of the hookworms, the species causing human helminthomas are rarely identified with accuracy. Oesophagostomum, especially O. bifurcum, are common parasites of livestock and animals like goats, pigs and non-human primates, although it seems that humans are increasingly becoming favorable hosts as well. The disease they cause, oesophagostomiasis, is known for the nodule formation it causes in the intestines of its infected hosts, which can lead to more serious problems such as dysentery. Although the routes of human infection have yet to be elucidated sufficiently, it is believed that transmission occurs through oral-fecal means, with infected humans unknowingly ingesting soil containing the infectious filariform larvae.

<i>Trichostrongylus</i> Genus of roundworms

Trichostrongylus species are nematodes, which are ubiquitous among herbivores worldwide, including cattle, sheep, donkeys, goats, deer, and rabbits. At least 10 Trichostrongylus species have been associated with human infections. Infections occur via ingestion of infective larvae from contaminated vegetables or water. Epidemiological studies indicate a worldwide distribution of Trichostrongylus infections in humans, with the highest prevalence rates observed in individuals from regions with poor sanitary conditions, in rural areas, or who are farmers / herders. Human infections are most prevalent in the Middle East and Asia, with a worldwide estimated prevalence of 5.5 million people.

Trichuris vulpis is a whipworm that lives in the large intestine of canines in its adult stages. Out of different types of worms, Trichuris vulpis is one of the smaller worms with a size ranging from 30–50 mm in length. As the name suggests, the worm has a whip-like shape with distinct features including a small, narrow anterior head, which is the digestive part of the worm, and a larger posterior tail, which is the reproductive part of the worm. Eggs from T. vulpis are oval shaped with bipolar plugs and contain a thick outer shell. Their sizes range from 72–90 μm in length and 32–40 μm in width. Because of their thick outer shell, T. vulpis eggs are very resistant to environmental extremes such as freezing or hot temperatures, thus allowing for their long viability in the outside world.

<span class="mw-page-title-main">Soil-transmitted helminthiasis</span> Roundworm infection contracted from contaminated soil

Soil-transmitted helminthiasis is a type of worm infection (helminthiasis) caused by different species of roundworms. It is caused specifically by those worms which are transmitted through soil contaminated with faecal matter and are therefore called soil-transmitted helminths. Three types of soil-transmitted helminthiasis can be distinguished: ascariasis, hookworm infection and whipworm infection. These three types of infection are therefore caused by the large roundworm A. lumbricoides, the hookworms Necator americanus or Ancylostoma duodenale and by the whipworm Trichuris trichiura.

References

  1. ↑ EMedicine|article|788570|Trichuris Trichiura
  2. 1 2 Cross, John H. (1996). "Enteric Nematodes of Humans". In Baron, Samuel (ed.). Medical Microbiology (4th ed.). Galveston: University of Texas Medical Branch at Galveston. ISBN   978-0-9631172-1-2.
  3. ↑ Hayes, K. S.; Bancroft, A. J.; Goldrick, M.; Portsmouth, C.; Roberts, I. S.; Grencis, R. K. (2010). "Exploitation of the Intestinal Microflora by the Parasitic Nematode Trichuris muris". Science. 328 (5984): 1391–4. Bibcode:2010Sci...328.1391H. doi:10.1126/science.1187703. PMC   3428897 . PMID   20538949.
  4. 1 2 3 4 "CDC - Trichuriasis". 2019-04-25.
  5. ↑ Citation error. See inline comment how to fix. [ verification needed ]
  6. ↑ "Trichuris trichiura definition - Medical Dictionary definitions of popular medical terms easily defined on MedTerms". Medterms.com. 2000-04-15. Retrieved 2009-05-19.
  7. 1 2 Stephenson, L.S.; Holland, C.V.; Cooper, E.S. (15 June 2001). "The public health significance of Trichuris trichiura" (PDF). Parasitology. 121 (S1): S73–S95. doi:10.1017/S0031182000006867. hdl: 2262/40190 . PMID   11386693. S2CID   7979360.
  8. ↑ Stephenson, L.S.; Holland, C.V.; Cooper, E.S. (2000). "The public health significance of Trichuris trichiura". Parasitology. 121 (S1): S73–S95. doi:10.1017/S0031182000006867. hdl: 2262/40190 . PMID   11386693. S2CID   7979360.
  9. ↑ "Otzi | Discovery & Facts | Britannica". www.britannica.com. Retrieved 2022-06-24.
  10. ↑ Stephenson, Lani S., et al. “Treatment with a Single Dose of Albendazole Improves Growth of Kenyan Schoolchildren with Hookworm, Trichuris Trichiura, and Ascaris Lumbricoides Infections.” The American Journal of Tropical Medicine and Hygiene, The American Society of Tropical Medicine and Hygiene, 1 July 1989, www.ajtmh.org/content/journals/10.4269/ajtmh.1989.41.78.
  11. ↑ Heyer, F.; Tourte-Schaeffer, Cl.; Ancelle, T.; Faurant, Cl.; Lapierre, J. (1 February 1982). "Le flubendazole : un progrès dans le traitement des helminthiases intestinales. A propos de 471 observations". Médecine et Maladies Infectieuses (in French). 12 (2): 57–61. doi:10.1016/S0399-077X(82)80047-4. ISSN   0399-077X.
  12. ↑ Crompton, DW (1999). "How much human helminthiasis is there in the world?". The Journal of Parasitology. 85 (3): 397–403. doi:10.2307/3285768. JSTOR   3285768. PMID   10386428.
  13. ↑ de Silva, Nilanthi R; Brooker, Simon; Hotez, Peter J; Montresor, Antonio; Engels, Dirk; Savioli, Lorenzo (2003). "Soil-transmitted helminth infections: updating the global picture". Trends in Parasitology. 19 (12): 547–51. doi: 10.1016/j.pt.2003.10.002 . PMID   14642761.
  14. ↑ "Trichuris trichiura". WrongDiagnosis.com. 2009-05-06. Retrieved 2009-05-19.
  15. ↑ Beer, RJ (January 1976). "The relationship between Trichuris trichiura (Linnaeus 1758) of man and Trichuris suis (Schrank 1788) of the pig". Research in Veterinary Science. 20 (1): 47–54. doi:10.1016/S0034-5288(18)33478-7. PMID   1257627.
  16. ↑ Hunter MM, McKay DM (2004). "Review article: helminths as therapeutic agents for inflammatory bowel disease". Aliment. Pharmacol. Ther. 19 (2): 167–77. doi: 10.1111/j.0269-2813.2004.01803.x . PMID   14723608. S2CID   73016367.
  17. ↑ Summers RW, Elliott DE, Urban JF, Thompson R, Weinstock JV (2005). "Trichuris suis therapy in Crohn's disease". Gut. 54 (1): 87–90. doi:10.1136/gut.2004.041749. PMC   1774382 . PMID   15591509.
  18. ↑ Summers RW, Elliott DE, Qadir K, Urban JF, Thompson R, Weinstock JV (2003). "Trichuris suis seems to be safe and possibly effective in the treatment of inflammatory bowel disease". Am. J. Gastroenterol. 98 (9): 2034–41. CiteSeerX   10.1.1.457.8633 . doi:10.1111/j.1572-0241.2003.07660.x. PMID   14499784. S2CID   2605979.
  19. ↑ Buning, J; et al. (March 2008). "Helminths as governors of inflammatory bowel disease". Gut. 57 (8): 1182–1183. doi:10.1136/gut.2008.152355. PMID   18628388. S2CID   29967284. in our patient Treg [regulatory T cells] activated by helminthosis [T. suis infestation] were most likely the key element protecting a host with latent ulcerative colitis against development of a severe protcocolitis. (1183)
  20. ↑ "Helminthic Therapy: How to put your Asthma, Colitis, IBD, Crohn's or Multiple Sclerosis into remission with hookworm". Asthmahookworm.com. Archived from the original on 2009-08-05. Retrieved 2009-05-19.[ self-published source ]
  21. ↑ "Allergies: Trichuris suis Ova (TSO) Therapy to Treat Food Allergies". Allergizer.com. Retrieved 2009-05-19.
  22. ↑ Bager, Peter; Kapel, Christian; Roepstorff, Allan; Thamsborg, Stig; Arnved, John; Rønborg, Steen; Kristensen, Bjarne; Poulsen, Lars K.; Wohlfahrt, Jan (2011-08-02). "Symptoms after Ingestion of Pig Whipworm Trichuris suis Eggs in a Randomized Placebo-Controlled Double-Blind Clinical Trial". PLOS ONE. 6 (8): e22346. Bibcode:2011PLoSO...622346B. doi: 10.1371/journal.pone.0022346 . ISSN   1932-6203. PMC   3149054 . PMID   21829616.
  23. ↑ Correale J, Farez M (2007). "Association between parasite infection and immune responses in multiple sclerosis". Annals of Neurology. 61 (2): 97–108. doi:10.1002/ana.21067. PMID   17230481. S2CID   1033417.
  24. ↑ "Asphelia Announces Initiation of an Independent TSO Trial for Multiple Sclerosis". redOrbit. 2008-04-07. Retrieved 2009-05-19.
  25. ↑ Klaver, Elsenoor J.; Kuijk, Loes M.; Laan, Lisa C.; Kringel, Helene; van Vliet, Sandra J.; Bouma, Gerd; Cummings, Richard D.; Kraal, Georg; van Die, Irma (2013). "Trichuris suis-induced modulation of human dendritic cell function is glycan-mediated". International Journal for Parasitology. 43 (3–4): 191–200. doi: 10.1016/j.ijpara.2012.10.021 . PMID   23220043.

Caroline Pomeroy, PhD July 9th, 2019.

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