Editing Trichuris trichiura

{{short description|Parasitic roundworm that causes intestinal infection}}
{{About|the worm|the infection|Trichuriasis}}
{{Speciesbox
 | name = Whipworm(s)
 | image = Trichuris trichiura, male.jpg
 | image_upright = 0.9
 | image_caption = Male
 | image2 = Trichuris trichiura, female.jpg
 | image2_upright = 0.9
 | image2_caption = Female
 | taxon = Trichuris trichiura
 | authority = ([[Carl Linnaeus|Linnaeus]], 1771)
|synonyms=''Ascaris trichiura'' <small>Linnaeus, 1771</small>
|synonyms_ref=<ref>{{GBIF|taxon=''Trichuris trichiura'' (Linnaeus, 1771)|id=4554218|access-date=11 September 2024}}</ref>
}}

'''''Trichuris trichiura''', '''Trichocephalus trichiuris''''' or '''whipworm''', is a [[parasitism|parasitic]] [[nematode|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.<ref>EMedicine|article|788570|Trichuris Trichiura</ref> The helminth is also known to cause [[rectal prolapse]].

== Life cycle ==
[[File:Trichuris trichiura Life Cycle.tif|thumb|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.<ref name="Books">{{cite book |first1=John H. |last1=Cross |chapter=Enteric Nematodes of Humans |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK8261/ |editor1-first=Samuel |editor1-last=Baron |year=1996 |title=Medical Microbiology |edition=4th |location=Galveston |publisher=University of Texas Medical Branch at Galveston |isbn=978-0-9631172-1-2 |archive-date=2021-04-10 |access-date=2017-09-17 |archive-url=https://web.archive.org/web/20210410225524/https://www.ncbi.nlm.nih.gov/books/NBK8261/ |url-status=live }}</ref> 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 [[Fomite|fomites]] and hatch in the human [[small intestine]], exploiting the intestinal microflora as a stimulus to hatching.<ref>{{cite journal |last1=Hayes |first1=K. S. |last2=Bancroft |first2=A. J. |last3=Goldrick |first3=M. |last4=Portsmouth |first4=C. |last5=Roberts |first5=I. S. |last6=Grencis |first6=R. K. |title=Exploitation of the Intestinal Microflora by the Parasitic Nematode Trichuris muris |journal=Science |volume=328 |issue=5984 |pages=1391–4 |year=2010 |pmid=20538949 |pmc=3428897 |doi=10.1126/science.1187703 |bibcode=2010Sci...328.1391H }}</ref> This is the location of growth and molting. The infective [[larva]]e penetrate the [[Intestinal villus|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,<ref name="cdc.gov">{{Cite web| url=https://www.cdc.gov/parasites/whipworm/| title=CDC - Trichuriasis| date=2019-04-25| access-date=2017-09-17| archive-date=2014-03-01| archive-url=https://web.archive.org/web/20140301000713/http://www.cdc.gov/parasites/whipworm/| url-status=live}}</ref> during which time females can lay up to 20,000 eggs per day.

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.<ref>{{cite journal|vauthors=Williams-Blangero S, VandeBerg JL, Subedi J, Jha B, Dyer TD, Blangero J|title=Two Quantitative Trait Loci Influence Whipworm (''Trichuris trichiura'') Infection in a Nepalese Population|journal=The Journal of Infectious Diseases|date=2008 |volume=197|issue=8|pages=1198–1203|doi=10.1086/533493|doi-access=free|pmid=18462166|pmc=4122289}}</ref>

==Morphology==
[[File:Cross-section of whipworm on microscopy.jpg|thumb|Cross-section of whipworm on microscopy]]
[[File:Trichuris trichiura eggs, including HE stain.jpg|thumb|right|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&nbsp;mm long compared to 30–45&nbsp;mm.<ref name="Medterms.com">{{cite web |url=http://www.medterms.com/script/main/art.asp?articlekey=12961 |title=Trichuris trichiura definition - Medical Dictionary definitions of popular medical terms easily defined on MedTerms |publisher=Medterms.com |date=2000-04-15 |access-date=2009-05-19 |archive-date=2011-06-06 |archive-url=https://web.archive.org/web/20110606011050/http://www.medterms.com/script/main/art.asp?articlekey=12961 |url-status=dead }}</ref> 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==
{{Main|Trichuriasis}}
[[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 [[open defecation|defecates outdoors]] or if untreated human feces is used as fertilizer, eggs are deposited on soil where they can mature into an infective stage.<ref name="cdc.gov"/> 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."<ref name="cdc.gov"/> 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 (anatomy)|lumen]], where it mates with nearby worms. The females can grow to {{convert|50|mm|in|abbr=on}} long.<ref name="Books" />

''Trichuris trichiura'' can cause the serious disease Trichuris dysentery syndrome (TDS), with chronic dysentery, anemia, rectal prolapse, and poor growth.<ref name=":0" /> TDS is treated with [[anthelminthics]] as well as iron supplementation for anemia.<ref>{{cite journal |last1=Stephenson |first1=L.S. |last2=Holland |first2=C.V. |last3=Cooper |first3=E.S. |title=The public health significance of Trichuris trichiura |journal=Parasitology |volume=121 |issue=S1 |pages=S73–S95 |doi=10.1017/S0031182000006867 |pmid=11386693 |year=2000 |hdl=2262/40190 |s2cid=7979360 |hdl-access=free }}</ref>

Whipworm commonly infects patients also infected with ''[[Giardia]]'', ''[[Entamoeba histolytica]]'', ''[[Ascaris lumbricoides]]'', and [[hookworm]]s.<ref>{{Cite web |title=Otzi {{!}} Discovery & Facts {{!}} Britannica |url=https://www.britannica.com/topic/Otzi |access-date=2022-06-24 |website=www.britannica.com |language=en |archive-date=2022-06-24 |archive-url=https://web.archive.org/web/20220624172716/https://www.britannica.com/topic/Otzi |url-status=live }}</ref>

==Treatment==
''Trichuris trichiura'' can be treated with a single dose of [[albendazole]].<ref>{{cite journal|vauthors=Stephenson LS, Latham MC, Kurz KM, Kinoti SN, Brigham H|title=Treatment with a Single Dose of Albendazole Improves Growth of Kenyan Schoolchildren with Hookworm, ''Trichuris Trichiura'', and ''Ascaris Lumbricoides'' Infections|volume=41|issue=1|pages=78–87|journal=The American Journal of Tropical Medicine and Hygiene|date=July 1989|doi=10.4269/ajtmh.1989.41.78|pmid=2764230}}</ref> In Kenya, half of a group of children, 98% of whom had ''Trichuris trichiura'' with or without infections by other [[soil-transmitted helminth]]s, 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.<ref>{{cite journal|vauthors=Stephenson LS, Latham MC, Adams EJ, Kinoti SN, Pertet A|title=Physical Fitness, Growth and Appetite of Kenyan School Boys with Hookworm, ''Trichuris trichiura'' and ''Ascaris lumbricoides'' Infections Are Improved Four Months After a Single Dose of Albendazole|journal=The Journal of Nutrition|volume=123|issue=6|year=1993|pages=1036–1046|pmid=8505663|doi=10.1093/jn/123.6.1036|doi-broken-date=1 November 2024 }}</ref>  Another treatment that can be used is [[mebendazole]], or [[flubendazole]].<ref>{{cite journal |last1=Heyer |first1=F. |last2=Tourte-Schaeffer |first2=Cl. |last3=Ancelle |first3=T. |last4=Faurant |first4=Cl. |last5=Lapierre |first5=J. |title=Le flubendazole : un progrès dans le traitement des helminthiases intestinales. A propos de 471 observations |journal=Médecine et Maladies Infectieuses |date=1 February 1982 |volume=12 |issue=2 |pages=57–61 |doi=10.1016/S0399-077X(82)80047-4 |url=https://www.sciencedirect.com/science/article/pii/S0399077X82800474 |language=fr |issn=0399-077X |archive-date=31 January 2023 |access-date=31 January 2023 |archive-url=https://web.archive.org/web/20230131084556/https://www.sciencedirect.com/science/article/pii/S0399077X82800474 |url-status=live }}</ref> The medication interferes with the parasite’s nutrient intake, which eventually leads to death. 

However, it has been shown that both albendazole and mebendazole have low cure rate for ''Trichuris thrichiura'' specifically, with treatments only achieving cure rates 30.7% for albendazole and 42.1% for mebendazole.<ref>{{Cite journal |last1=Moser |first1=Wendelin |last2=Schindler |first2=Christian |last3=Keiser |first3=Jennifer |date=2017-09-25 |title=Efficacy of recommended drugs against soil transmitted helminths: systematic review and network meta-analysis |url=https://www.bmj.com/content/358/bmj.j4307 |journal=BMJ |language=en |volume=358 |pages=j4307 |doi=10.1136/bmj.j4307 |issn=0959-8138 |pmc=5611648 |pmid=28947636 |archive-date=2024-05-17 |access-date=2024-10-17 |archive-url=https://web.archive.org/web/20240517072144/https://www.bmj.com/content/358/bmj.j4307 |url-status=live }}</ref>

==Epidemiology==
There is a worldwide distribution of ''Trichuris trichiura'', with an estimated one billion human infections.<ref>{{cite journal |last1=Crompton |first1=DW |title=How much human helminthiasis is there in the world? |journal=The Journal of Parasitology |volume=85 |issue=3 |pages=397–403 |year=1999 |pmid=10386428 |doi=10.2307/3285768|jstor=3285768 }}</ref><ref>{{cite journal |last1=de Silva |first1=Nilanthi R |last2=Brooker |first2=Simon |last3=Hotez |first3=Peter J |last4=Montresor |first4=Antonio |last5=Engels |first5=Dirk |last6=Savioli |first6=Lorenzo |title=Soil-transmitted helminth infections: updating the global picture |journal=Trends in Parasitology |volume=19 |issue=12 |pages=547–51 |year=2003 |pmid=14642761 |doi=10.1016/j.pt.2003.10.002 |doi-access=free }}</ref><ref name="Trichuris trichiura">{{cite web |url=http://www.wrongdiagnosis.com/medical/trichuris_trichiura.htm |title=Trichuris trichiura |publisher=WrongDiagnosis.com |date=2009-05-06 |access-date=2009-05-19 |archive-date=2004-06-19 |archive-url=https://web.archive.org/web/20040619123103/http://www.wrongdiagnosis.com/medical/trichuris_trichiura.htm |url-status=live }}</ref><ref name=":0">{{cite journal|last1=Stephenson|first1=L.S.|last2=Holland|first2=C.V.|last3=Cooper|first3=E.S.|date=15 June 2001|title=The public health significance of ''Trichuris trichiura''|url=http://www.tara.tcd.ie/bitstream/2262/40190/1/The%20public%20health%20significance%20of%20Trichuris%20trichiura.pdf|journal=Parasitology|volume=121|issue=S1|pages=S73–S95|doi=10.1017/S0031182000006867|pmid=11386693|hdl-access=free|hdl=2262/40190|s2cid=7979360|author1-link=Lani Stephenson }}</ref> 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.<ref>{{cite journal |last1=Beer |first1=RJ |title=The relationship between Trichuris trichiura (Linnaeus 1758) of man and Trichuris suis (Schrank 1788) of the pig. |journal=Research in Veterinary Science |date=January 1976 |volume=20 |issue=1 |pages=47–54 |pmid=1257627 |doi=10.1016/S0034-5288(18)33478-7 }}</ref>

WHO have since 2001 had a strategy for control of soil-transmitted helminths, including whipworms. This strategy entails treating at-risk individuals in the endemic areas. Risk groups for whipworm infections are children at preschool and school-aged children, people with specific high-risk jobs, women in reproductive and pregnant and breastfeeding women. The periodic treatment of the risk groups is done through either deworming campaigns or preventative chemotherapy.<ref>{{Cite web |title=Soil-transmitted helminth infections |url=https://www.who.int/news-room/fact-sheets/detail/soil-transmitted-helminth-infections |access-date=2024-10-18 |website=www.who.int |language=en |archive-date=2024-07-28 |archive-url=https://web.archive.org/web/20240728224948/https://www.who.int/news-room/fact-sheets/detail/soil-transmitted-helminth-infections |url-status=live }}</ref>

==Treatment of inflammatory disorders==
{{Main|Helminthic therapy}}
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<ref>{{cite journal |vauthors=Hunter MM, McKay DM |title=Review article: helminths as therapeutic agents for inflammatory bowel disease |journal=Aliment. Pharmacol. Ther. |volume=19 |issue=2 |pages=167–77 |year=2004 |pmid=14723608 |doi=10.1111/j.0269-2813.2004.01803.x|s2cid=73016367 |doi-access=free }}</ref><ref name="pmid15591509">{{cite journal |vauthors=Summers RW, Elliott DE, Urban JF, Thompson R, Weinstock JV |title=Trichuris suis therapy in Crohn's disease |journal=Gut |volume=54 |issue=1 |pages=87–90 |year=2005 |pmid=15591509 |pmc=1774382 |doi=10.1136/gut.2004.041749}}</ref><ref name="pmid14499784">{{cite journal |vauthors=Summers RW, Elliott DE, Qadir K, Urban JF, Thompson R, Weinstock JV |title=Trichuris suis seems to be safe and possibly effective in the treatment of inflammatory bowel disease |journal=Am. J. Gastroenterol. |volume=98 |issue=9 |pages=2034–41 |year=2003 |doi=10.1111/j.1572-0241.2003.07660.x |pmid=14499784 |citeseerx=10.1.1.457.8633 |s2cid=2605979 }}</ref> and to a lesser extent [[ulcerative colitis]]<ref>{{cite journal | title = Helminths as governors of inflammatory bowel disease | journal = Gut | date = March 2008 | first = J | last = Buning | pmid = 18628388 | volume = 57 | issue = 8 | pages = 1182–1183| doi =  10.1136/gut.2008.152355 | s2cid = 29967284 | quote = 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)|display-authors=etal}}</ref> 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]],<ref>{{cite web |url=http://www.asthmahookworm.com |title=Helminthic Therapy: How to put your Asthma, Colitis, IBD, Crohn's or Multiple Sclerosis into remission with hookworm |publisher=Asthmahookworm.com |access-date=2009-05-19 |archive-url=https://web.archive.org/web/20090805233443/http://asthmahookworm.com/ |archive-date=2009-08-05 |url-status=dead }}{{self-published source|date=June 2015}}</ref>{{self-published inline|date=June 2015}} [[allergy]],<ref>{{cite web |url=http://www.allergizer.com/50226711/trichuris_suis_ova_tso_therapy_to_treat_food_allergies.php |title=Allergies: Trichuris suis Ova (TSO) Therapy to Treat Food Allergies |publisher=Allergizer.com |access-date=2009-05-19 |archive-date=2009-05-12 |archive-url=https://web.archive.org/web/20090512190910/http://www.allergizer.com/50226711/trichuris_suis_ova_tso_therapy_to_treat_food_allergies.php |url-status=dead }}</ref> and other inflammatory disorders.<ref>{{Cite journal|last1=Bager|first1=Peter|last2=Kapel|first2=Christian|last3=Roepstorff|first3=Allan|last4=Thamsborg|first4=Stig|last5=Arnved|first5=John|last6=Rønborg|first6=Steen|last7=Kristensen|first7=Bjarne|last8=Poulsen|first8=Lars K.|last9=Wohlfahrt|first9=Jan|date=2011-08-02|title=Symptoms after Ingestion of Pig Whipworm Trichuris suis Eggs in a Randomized Placebo-Controlled Double-Blind Clinical Trial|journal=PLOS ONE|volume=6|issue=8|pages=e22346|doi=10.1371/journal.pone.0022346|issn=1932-6203|pmc=3149054|pmid=21829616|bibcode=2011PLoSO...622346B|doi-access=free}}</ref> Some scientific evidence suggests that the course of [[multiple sclerosis]] may be very favorably altered by helminth infection;<ref name="pmid17230481">{{cite journal |vauthors=Correale J, Farez M |title=Association between parasite infection and immune responses in multiple sclerosis |journal=Annals of Neurology |volume=61 |issue=2 |pages=97–108 |year=2007 |pmid=17230481 |doi=10.1002/ana.21067|s2cid=1033417 }}</ref> TSO is being studied as a treatment for this disease.<ref>{{cite web |url=http://www.redorbit.com/news/health/1329983/asphelia_announces_initiation_of_an_independent_tso_trial_for_multiple/index.html |title=Asphelia Announces Initiation of an Independent TSO Trial for Multiple Sclerosis |publisher=redOrbit |date=2008-04-07 |access-date=2009-05-19 |archive-date=2023-08-29 |archive-url=https://web.archive.org/web/20230829063103/https://www.redorbit.com/news/health/1329983/asphelia_announces_initiation_of_an_independent_tso_trial_for_multiple/index.html |url-status=live }}</ref><ref>{{cite journal |last1=Klaver |first1=Elsenoor J. |last2=Kuijk |first2=Loes M. |last3=Laan |first3=Lisa C. |last4=Kringel |first4=Helene |last5=van Vliet |first5=Sandra J. |last6=Bouma |first6=Gerd |last7=Cummings |first7=Richard D. |last8=Kraal |first8=Georg |last9=van Die |first9=Irma |title=Trichuris suis-induced modulation of human dendritic cell function is glycan-mediated |journal=International Journal for Parasitology |volume=43 |issue=3–4 |pages=191–200 |year=2013 |pmid=23220043 |doi=10.1016/j.ijpara.2012.10.021 |doi-access=free }}</ref>

== See also ==
[[Defecography]]

== References ==
{{Reflist|30em}}

Caroline Pomeroy, PhD July 9th, 2019.

== External links ==
{{Commons category}}
* {{EMedicine|article|788570|Trichuris Trichiura}}
* [http://edition.cnn.com/2010/HEALTH/12/09/worms.health/index.html Man finds extreme healing eating parasitic worms, by Elizabeth Cohen, CNN Senior Medical CorrespondentDecember 9, 2010]
* [https://web.archive.org/web/20080904220158/http://www.livescience.com/humanbiology/060610_worms.html Potential Disease Treatment: Swallow Some Worms]
* [https://www.theglobeandmail.com/servlet/story/RTGAM.20060609.worms0609/BNStory/specialScienceandHealth/home Globe and Mail: Sometimes having worms is good]
* [http://news.bbc.co.uk/2/hi/science/nature/6727665.stm BBC article mentions the Iceman had Whipworm]

{{Helminthiases}}
{{Taxonbar|from=Q1154414}}

[[Category:Conditions diagnosed by stool test]]
[[Category:Trichocephalida]]
[[Category:Parasitic nematodes of humans]]
[[Category:Veterinary helminthology]]
[[Category:Nematodes described in 1771]]
[[Category:Taxa named by Carl Linnaeus]]