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| | name = Pinworm | | | name = Pinworm |
| ICD 127.4 | | ICD 127.4 |
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| | image = Threadworm.jpg | | | image = Threadworm.jpg |
| | image_width = 250px | | | image_width = 250px |
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| {{CMG}} | | {{CMG}} |
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| ==Overview== | | ==[[Pinworm overview|Overview]]== |
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| The '''pinworm''' (Genus '''''Enterobius''''') is a [[parasitic]] [[roundworm]] of the phylum [[Nematoda]].
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| == Forms of worm ==
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| The best known is the human pinworm ''[[Enterobius vermicularis]]'' and the more recently discovered ''[[Enterobius gregorii]]''. The adult pinworm male is 1–4 [[millimetre|mm]] in length, while the adult female is 8–13 mm and possesses the long, pin-shaped posterior for which the worm is named. The human pinworm is commonly found in children, but adults may also be affected.
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| == Habitat == | | ==[[Pinworm classification|Classification]]== |
| The pinworm lives in the large intestine and cecum. It is found worldwide, and causes the most common infection [[enterobiasis]] in humans. Unlike many other [[intestinal parasite]]s, the pinworm does not usually enter the [[bloodstream]] or any other organs besides the intestines. Only in rare cases pinworms are found in the [[vagina]], and even more rarely in the [[uterus]], [[fallopian tube]]s, [[liver]], and [[peritoneum]], but the worms cannot survive long in these places.
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| The human pinworm ''Enterobius vermicularis'' is a ubiquitous parasite of man, it being estimated that over 200 million people are infected annually. It is more common in the temperate regions of Western Europe and North America, (it being relatively rare in the tropics) and is found particularly in children. Samples of Caucasian children in the U.S.A. and Canada have shown incidences of infection of between 30% to 80%, with similar levels in Europe.<ref>[http://www.path.cam.ac.uk/~schisto/Nematodes/Enterobius.html The Human Pinworm]</ref>
| | ==[[Pinworm historical perspective|Historical Perspective]]== |
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| == Reproduction == | | ==[[Pinworm pathophysiology|Pathophysiology]]== |
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| After mating, the male dies. The female migrates to the [[anus]] and emerges, usually during the night, to deposit about 10,000 to 20,000 [[egg (biology)|egg]]s in the perianal area (around the anus). She then secretes a substance which causes a very strong [[itch]]ing sensation, inciting the host to scratch the area and thus transfer some of the eggs to the fingers. Eggs can also be transferred to cloth, toys, and the bathtub. Once ingested orally, the [[larva|larvae]] hatch in the small intestine specifically the duodenum and migrate back to the large intestine where they mature, maturity is reached in 30-45 days. The eggs can survive for 2 to 3 weeks on their own outside of the human body. In some cases, the larvae will hatch in the peri-anal area and travel back inside the anus, up the rectum, and back into the intestines where they mature.<ref>Rudolph's Pediatrics - 21st Ed. 2003; Current Medical Diagnosis & Treatment - 45th Ed. 2006</ref>
| | ==[[Pinworm epidemiology and demographics|Epidemiology & Demographics]]== |
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| == Effects == | | ==[[Pinworm risk factors|Risk Factors]]== |
| Except for itching, pinworm infestation does not usually cause any damage to the body. Sleep disturbance may arise from the itching or crawling sensations. Some case reports suggest that severe infestation may be associated with an increased risk for [[appendicitis]]. There is also some evidence of an association between [[enterobiasis]] and diminished zinc levels.
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| == Diagnosis == | | ==[[Pinworm screening|Screening]]== |
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| Diagnosis is often made clinically by observing the female worm (or many worms) in the peri-anal region, but can also be made using the [["scotch-tape" test]], in which the sticky side of a strip of [[cellophane]] tape is pressed against the peri-anal skin, then examined under a microscope for pinworm eggs.
| | ==[[Pinworm causes|Causes]]== |
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| The actual worms may be seen in the host's faeces; however the eggs are invisible to the naked eye.
| | ==[[Pinworm differential diagnosis|Differentiating Pinworm from other Diseases]]== |
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| The diagnostic characteristics are: size 50-60 µm by 20-32 µm; typical elongated shape, with one convex side and one flattened side and colorless shell <ref>{{cite web | url = http://pathmicro.med.sc.edu/parasitology/nematodes.htm| title =PARASITOLOGY - CHAPTER FOUR NEMATODES (Round Worms) | accessdate = 2007-10-18| publisher = The Board of Trustees of the University of South Carolina}}</ref>.
| | ==[[Pinworm natural history|Natural History, Complications & Prognosis]]== |
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| On [[histology|histologic]] cross-section, alae or wings (running the length of the worm) are identifying features of the pinworm (see micrograph).<ref>Diagnostic Findings Enterobiasis. [[Centers for Disease Control and Prevention]]. URL: [http://www.dpd.cdc.gov/dpdx/HTML/Enterobiasis.htm http://www.dpd.cdc.gov/dpdx/HTML/Enterobiasis.htm]. Accessed on: August 6, 2008.</ref>
| | ==[[Pinworm diagnosis|Diagnosis]]== |
| | | [[Pinworm history and symptoms|History & Symptoms]] | [[Pinworm physical examination|Physical Examination]] | [[Pinworm staging| Staging]] | [[Pinworm laboratory tests|Lab Tests]] | [[Pinworm electrocardiogram|Electrocardiogram]] |[[Pinworm chest x ray|Chest X Ray]] | [[Pinworm CT|CT]] | [[Pinworm MRI|MRI]] | [[Pinworm echocardiography or ultrasound|Echocardiography or Ultrasound]] | [[Pinworm other imaging findings|Other Imaging Findings]] | [[Pinworm other diagnostic studies|Other Diagnostic Studies]] |
| ==Appendix: Pinworms==
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| {{#ev:youtube|PkemlmA_tf0}}
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| ==Additional images==
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| <gallery>
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| Image:Threadworm.jpg|Two pinworms, captured on emergence from the anus. Markings are 1 mm apart.
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| Image:Pinworms in the Appendix (1).jpg|Pinworms are sometimes diagnosed incidentally by [[pathology]]. [[Micrograph]] of pinworms in the [[vermiform appendix|appendix]]. [[H&E stain]].
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| Image:Pinworms in the Appendix (2).jpg|High magnification [[micrograph]] of a pinworm in cross-section in the [[vermiform appendix|appendix]]. [[H&E stain]].
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| Image:Pinworms in the Appendix (3).jpg|High magnification micrograph of a pinworm in cross-section in the appendix. H&E stain.
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| Image:Evermiculariseggs.jpg|Enterobius vermicularis egg under a light microscope.
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| Image:Eggs of Enterobius vermicularis 5229 lores.jpg|Pinworm eggs are easily seen under a microscope.
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| Image:Evermicularis_worm4_HB.jpg|thumb|Pinworms are sometimes diagnosed incidentally by [[pathology]]. [[Micrograph]] of male pinworm in cross-section. Alae (blue arrow), intestine (red arrow) and testis (black arrow). [[H&E stain]].
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| image:Evermicularis adult2 Norway.jpg|A pinworm (''Enterobius vermicularis'').
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| </gallery>
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| ==Treatment== | | ==Treatment== |
| Anti-pinworm drugs such as Albenza ([[albendazole]]), Vermox ([[mebendazole]]), or Pin-X ([[pyrantel pamoate]]) are commonly used to treat pinworms. It is not a necessity to visit a doctor to get these drugs, as Pin-X is available as an over the counter medication (Albenza and Vermox are prescription in the US); ask a pharmacist for medicines to treat pinworms (or threadworms as they are known in the UK). These medicines kill the pinworms 95% of the time, but do not kill the eggs. The person being treated may have to return after a time of two weeks to be re-treated. Another precaution is to wash the hands before eating (to prevent any pinworm eggs under fingernails from being ingested) and to wash any area or clothes that have touched or been in the vicinity of the infected areas. Treating the entire family is often necessary for cure.
| | [[Pinworm medical therapy|Medical Therapy]] | [[Pinworm surgery|Surgery]] | [[Pinworm primary prevention|Primary Prevention]] | [[Pinworm secondary prevention|Secondary Prevention]] ''' ''' |
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| ==References== | | ==References== |
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| {{Reflist|2}} | | {{Reflist|2}} |
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| ==External links==
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| *[http://content.nejm.org/cgi/content/full/354/13/e12/DC1 Video of infected colon]
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| ==External Links==
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| * [http://content.nejm.org/cgi/content/full/354/13/e12/DC1 New England Journal of Medicine Video.] A 55-year-old man presented with intermittent, crampy pain in the right lower quadrant of the abdomen. A colonoscopy was ordered and revealed multiple mobile 1-cm worms, Enterobius vermicularis, in the cecum.
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| * [http://www.path.cam.ac.uk/~schisto/Nematodes/Enterobius.html The Human Pinworm:] The human pinworm Enterobius vermicularis is a ubiquitous parasite of man, it being estimated that over 200 million people are infected annually. It is more common in the temperate regions of Western Europe and North America, (it being relatively rare in the tropics) and is found particularly in children. Samples of Caucasian children in the U.S.A. and Canada have shown incidences of infection of between 30% to 80%, with similar levels in Europe.
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| [[Category:Parasites]] | | [[Category:Parasites]] |
