View source for Helminthiasis

{{short description|Any macroparasitic disease caused by helminths}}
{{about|the infection|the organisms|Helminths}}
{{Infobox medical condition (new)
| name            = Helminthiasis
| image           = Ascaris infection in the x-ray image- ascaris arranged tidily along the long axis of the small bowel (South Africa) (16424840021).jpg
| caption         = [[Ascaris]] worms (one type of [[helminth]]) in the small bowel of an infected person (X-ray image with barium as contrast medium)
| pronounce       = {{IPAc-en|ˌ|h|ɛ|l|m|ɪ|n|ˈ|θ|aɪ|ə|s|ɪ|s}}
| field           =
| synonyms        = Worm infection, helminthosis, helminthiases, helminth infection
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'''Helminthiasis''', also known as '''worm infection''', is any [[macroparasite|macroparasitic]] disease of humans and other animals in which a part of the body is infected with [[parasitism|parasitic]] [[worm]]s, known as [[helminths]]. There are numerous species of these [[parasite]]s, which are broadly classified into [[cestoda|tapeworms]], [[trematoda|flukes]], and [[nematode|roundworm]]s. They often live in the [[gastrointestinal tract]] of their [[host (biology)|host]]s, but they may also burrow into other [[organ (anatomy)|organ]]s, where they induce physiological damage.

[[Soil-transmitted helminthiasis]] and [[schistosomiasis]] are the most important helminthiases, and are among the [[neglected tropical diseases]].<ref name="Neglected Tropical Diseases">{{Cite web |date=6 June 2011 |title=Neglected Tropical Diseases |url=https://www.cdc.gov/globalhealth/ntd/diseases/index.html |access-date=28 November 2014 |website=cdc.gov}}</ref> These group of helminthiases have been targeted under the joint action of the world's leading [[pharmaceutical industry|pharmaceutical companies]] and [[non-governmental organization]]s through a project launched in 2012 called the [[London Declaration on Neglected Tropical Diseases]], which aimed to control or eradicate certain neglected tropical diseases by 2020.<ref>{{Cite web |last=London Declaration |date=30 January 2012 |title=London Declaration on Neglected Tropical Diseases |url=http://www.dfid.gov.uk/Documents/publications1/NTD%20Event%20-%20London%20Declaration%20on%20NTDs.pdf |access-date=26 March 2013}}</ref>

Helminthiasis has been found to result in poor birth outcome, poor cognitive development, poor school and work performance, poor socioeconomic development, and poverty.<ref name="who">Report of a WHO Expert Committee (1987). [http://whqlibdoc.who.int/trs/WHO_TRS_749.pdf Prevention and Control of Intestinal Parasitic Infections]. World Health Organization, Technical Report Series 749.</ref><ref name="books.google.com">Del Rosso, Joy Miller and Tonia Marek (1996). [https://books.google.com/books?id=XeY4-Y15cCgC&dq=class%20action%3A%20improving%20school%20performance&pg=PP1 Class Action: Improving School Performance in the Developing World through Better Health and Nutrition]. The [[World Bank]], Directions in Development.</ref> Chronic illness, [[malnutrition]], and [[anemia]] are further examples of secondary effects.<ref name="WHO2012">{{Cite journal |vauthors=WHO |year=2012 |title=Research priorities for helminth infections |journal=World Health Organization Technical Report Series |volume=972 |issue=972 |pages=xv-xvii, 1–174, back cover |pmid=23420950}}</ref>

Soil-transmitted helminthiases are responsible for parasitic infections in as much as a quarter of the human population worldwide.<ref name="WHO2015">{{Cite web |date=May 2015 |title=Soil-transmitted helminth infections |url=https://www.who.int/mediacentre/factsheets/fs366/en |url-status=dead |archive-url=https://web.archive.org/web/20120820003930/http://www.who.int/mediacentre/factsheets/fs366/en/ |archive-date=August 20, 2012 |access-date=30 June 2015 |website=Fact sheet N°366}}</ref> One well-known example of soil-transmitted helminthiases is [[ascariasis]].
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==Types of parasitic helminths==
[[File:Ascariasis LifeCycle - CDC Division of Parasitic Diseases.png|thumb|upright=1.35|right|''Ascaris'' life cycle: Adult worms in the lumen of the small intestine (1). The female produces eggs (approximately 200,000 per day) that are excreted with the feces (2). Unfertilized eggs are harmless, but fertilized ones are infective after 18 days to several weeks (3). Infective eggs are ingested (4), enter the gut (5), develop into larvae in the intestine, and penetrate the blood vessel to enter lungs, where they develop further (6), after 10 to 14 days, penetrate the alveolar walls, ascend the bronchial tree to the throat, and are re-swallowed (7). Upon reaching the small intestine, they develop into adult worms (8). It takes 2 to 3 months for one complete cycle. Adult worms can live 1 to 2 years.]]
[[File:Collage Helminth eggs.png|thumb|Collage of various helminth eggs, from left to right: ''Trichosomoides'' egg, ''[[Ascaris lumbricoides]]'' with larva hatching, sample of adult roundworms, ''[[Hymenolepis nana]]'', ''Schistosoma mansoni'' and ''[[Toxocara canis]]'' with larva hatching]]

Of all the known helminth species, the most important helminths with respect to understanding their transmission pathways, their control, inactivation and enumeration in samples of human excreta from dried feces, [[faecal sludge]], [[wastewater]], and [[sewage sludge]] are:<ref>{{Cite journal |vauthors=Maya C, Torner-Morales FJ, Lucario ES, Hernández E, Jiménez B |date=October 2012 |title=Viability of six species of larval and non-larval helminth eggs for different conditions of temperature, pH and dryness |journal=Water Research |volume=46 |issue=15 |pages=4770–82 |doi=10.1016/j.watres.2012.06.014 |pmid=22794801|bibcode=2012WatRe..46.4770M }}</ref>
* soil-transmitted helminths, including ''[[Ascaris lumbricoides]]'' (the most common worldwide), ''[[Trichuris trichiura]]'', ''[[Necator americanus]]'', ''[[Strongyloides stercoralis]]'' and ''[[Ancylostoma duodenale]]''
* ''[[Hymenolepis nana]]''
* ''[[Taenia saginata]]''
* ''[[Enterobius]]''
* ''[[Fasciola hepatica]]''
* ''[[Schistosoma mansoni]]''
* ''[[Toxocara canis]]''
* ''[[Toxocara cati]]''

Helminthiases are classified as follows (the disease names end with "-sis" and the causative worms are in brackets):

===Roundworm infection (nematodiasis)===
* [[Filariasis]] ([[Filarioidea|filarial worms]]: ''[[Wuchereria bancrofti]]'', ''[[Brugia malayi]]'' infection)
** [[Onchocerciasis]] (''[[Onchocerca volvulus]]'' infection)
* [[Soil-transmitted helminthiasis]] – this includes [[ascariasis]] (''Ascaris lumbricoides'' infection), [[trichuriasis]] (''[[Trichuris]]'' infection), and [[hookworm infection]] (includes [[necatoriasis]] and ''Ancylostoma duodenale'' infection)
* [[Trichostrongyliasis]] (''[[Trichostrongylus]]'' spp. infection)
* [[Dracunculiasis]] ([[guinea worm]] infection)
* [[Baylisascaris]] (raccoon roundworm, may be transmitted to pets, livestock, and humans)

===Tapeworm infection (cestodiasis)===
* [[Echinococcosis]] (''[[Echinococcus]]'' infection)
* [[Hymenolepiasis]] (''[[Hymenolepis (flatworm)|Hymenolepis]]'' infection)
* [[Taeniasis]]/[[cysticercosis]] (''[[Taenia (flatworm)|Taenia]]'' infection)
* [[Coenurosis]] (''[[Taenia multiceps|T. multiceps]]'', ''[[Taenia serialis|T. serialis]]'', ''[[Taenia glomerata|T. glomerata]]'', and ''[[Taenia brauni|T. brauni]]'' infection)

===Trematode infection (trematodiasis)===
* [[Amphistomiasis]] ([[Echinostomida|amphistomes]] infection)
* [[Clonorchiasis]] (''[[Clonorchis sinensis]]'' infection)
* [[Fascioliasis]] (''[[Fasciola]]'' infection)
* [[Fasciolopsiasis]] (''[[Fasciolopsis buski]]'' infection)
* [[Opisthorchiasis]] (''[[Opisthorchis]]'' infection)
* [[Paragonimiasis]] (''[[Paragonimus]]'' infection)
* [[Schistosomiasis]]/bilharziasis (''[[Schistosoma]]'' infection)

===Acanthocephala infection===
* ''[[Moniliformis]]'' infection

==Signs and symptoms==
[[File:4951113771 b76622322c bdracunculose.jpg|thumb|Example clinical photo: Guinea worm infection ([[dracunculiasis]]), worm coming out of the foot of an infected person.]]
[[File:Ascaris infection- Antimesenteric splitting of the outer layers of the bowel wall due to a large amount of ascaris (South Africa) (15806559913).jpg|thumb|Ascaris infection: Antimesenteric splitting of the outer layers of the bowel wall due to a large amount of ascaris (South Africa)]]

The signs and symptoms of helminthiasis depend on a number of factors including: the site of the infestation within the body; the type of worm involved; the number of worms and their volume; the type of [[pathology|damage]] the infesting worms cause; and, the immunological response of the body. Where the burden of parasites in the body is light, there may be no symptoms.{{citation needed|date=January 2021}}

Certain worms may cause particular constellations of symptoms. For instance, [[taeniasis]] can lead to [[epilepsy|seizures]] due to [[neurocysticercosis]].<ref>{{Cite journal |vauthors=Del Brutto OH |year=2012 |title=Neurocysticercosis: a review |journal=TheScientificWorldJournal |volume=2012 |pages=159821 |doi=10.1100/2012/159821 |pmc=3261519 |pmid=22312322 |doi-access=free }}</ref>

===Mass and volume===
In extreme cases of [[intestine|intestinal]] infestation, the mass and volume of the worms may cause the outer layers of the intestinal wall, such as the muscular layer, to tear. This may lead to [[peritonitis]], [[volvulus]], and [[gangrene]] of the intestine.<ref name=":9">{{Cite journal |vauthors=Madiba TE, Hadley GP |date=February 1996 |title=Surgical management of worm volvulus |journal=South African Journal of Surgery. Suid-Afrikaanse Tydskrif vir Chirurgie |volume=34 |issue=1 |pages=33–5; discussion 35–6 |pmid=8629187}}</ref>

===Immunological response===
As pathogens in the body, helminths induce an [[immunity (medical)|immune]] response. Immune-mediated [[inflammation|inflammatory]] changes occur in the skin, [[lung]], [[liver]], intestine, [[central nervous system]], and eyes. Signs of the body's immune response may include [[eosinophilia]], [[edema]], and [[arthritis]].<ref name="min">{{Cite journal |vauthors=Minciullo PL, Cascio A, David A, Pernice LM, Calapai G, Gangemi S |date=October 2012 |title=Anaphylaxis caused by helminths: review of the literature |journal=European Review for Medical and Pharmacological Sciences |volume=16 |issue=11 |pages=1513–8 |pmid=23111963}}</ref> An example of the immune response is the [[hypersensitivity]] reaction that may lead to [[anaphylaxis]]. Another example is the migration of ''[[Ascaris]]'' larvae through the [[bronchus|bronchi]] of the lungs causing [[asthma]].<ref name="John">{{Cite book |title=Markell and Vogue's Medical Parasitology, 9th Edition |vauthors=John DT, William Jr AP |publisher=Saunders Elsevier Press |year=2006 |isbn=0721647936}}</ref>

===Secondary effects===

====Immune changes====
{{See also|Effects of parasitic worms on the immune system}}
[[File:Helminth in appendix 20x.jpg|thumb|Micrograph of cut section of human [[Appendix (anatomy)|appendix]] showing a pin worm.]]
In humans, [[T helper cell]]s and [[eosinophil granulocyte|eosinophils]] respond to helminth infestation. It is well established that T helper 2 cells are the central players of protective immunity to helminths,<ref>{{Cite journal |vauthors=Cortés A, Muñoz-Antoli C, Esteban JG, Toledo R |date=September 2017 |title=Th2 and Th1 Responses: Clear and Hidden Sides of Immunity Against Intestinal Helminths |url=https://doi.org/10.1016/j.pt.2017.05.004 |journal=Trends in Parasitology |volume=33 |issue=9 |pages=678–693 |doi=10.1016/j.pt.2017.05.004 |pmid=28566191|url-access=subscription }}</ref> while the roles for B cells and antibodies are context-dependent.<ref>{{Cite journal |vauthors=Zaini A, Good-Jacobson KL, Zaph C |date=May 2021 |title=Context-dependent roles of B cells during intestinal helminth infection |journal=PLOS Neglected Tropical Diseases |volume=15 |issue=5 |pages=e0009340 |doi=10.1371/journal.pntd.0009340 |pmc=8118336 |pmid=33983946 |doi-access=free }}</ref> Inflammation leads to encapsulation of egg deposits throughout the body. Helminths excrete into the intestine toxic substances after they feed. These substances then enter the circulatory and lymphatic systems of the host body.{{citation needed|date=January 2021}}

Chronic immune responses to helminthiasis may lead to increased susceptibility to [[coinfection|other infections]] such as [[tuberculosis]], [[HIV]], and [[malaria]].<ref>{{Cite journal |vauthors=van Riet E, Hartgers FC, Yazdanbakhsh M |year=2007 |title=Chronic helminth infections induce immunomodulation: consequences and mechanisms |journal=Immunobiology |volume=212 |issue=6 |pages=475–90 |doi=10.1016/j.imbio.2007.03.009 |pmid=17544832}}</ref><ref>{{Cite journal |vauthors=Mkhize-Kwitshana ZL, Mabaso MH |date=June 2012 |title=Status of medical parasitology in South Africa: new challenges and missed opportunities |journal=Trends in Parasitology |volume=28 |issue=6 |pages=217–9 |doi=10.1016/j.pt.2012.03.005 |pmid=22525798}}</ref><ref>{{Cite journal |vauthors=Borkow G, Bentwich Z |year=2000 |title=Eradication of helminthic infections may be essential for successful vaccination against HIV and tuberculosis |url=http://www.scielosp.org/scielo.php?pid=S0042-96862000001100013&script=sci_arttext |journal=Bulletin of the World Health Organization |volume=78 |issue=11 |pages=1368–9 |pmc=2560630 |pmid=11143198 |hdl=10665/268007 |archive-date=2018-09-21 |access-date=2014-10-21 |archive-url=https://web.archive.org/web/20180921230148/https://scielosp.org/scielo.php?pid=S0042-96862000001100013&script=sci_arttext |url-status=dead }}</ref> There is conflicting information about whether deworming reduces HIV progression and viral load and increases [[CD4]] counts in [[Management of HIV/AIDS|antiretroviral]] naive and experienced individuals, although the most recent Cochrane review found some evidence that this approach might have favorable effects.<ref>{{Cite journal |display-authors=6 |vauthors=Lankowski AJ, Tsai AC, Kanyesigye M, Bwana M, Haberer JE, Wenger M, Martin JN, Bangsberg DR, Hunt PW, Siedner MJ |date=August 2014 |title=Empiric deworming and CD4 count recovery in HIV-infected Ugandans initiating antiretroviral therapy |journal=PLOS Neglected Tropical Diseases |volume=8 |issue=8 |pages=e3036 |doi=10.1371/journal.pntd.0003036 |pmc=4125278 |pmid=25101890 |doi-access=free }}</ref><ref>{{Cite journal |vauthors=Means AR, Burns P, Sinclair D, Walson JL |date=April 2016 |title=Antihelminthics in helminth-endemic areas: effects on HIV disease progression |journal=The Cochrane Database of Systematic Reviews |volume=2016 |issue=4 |pages=CD006419 |doi=10.1002/14651858.CD006419.pub4 |pmc=4963621 |pmid=27075622}}</ref> Helminth infection also lowers the immune responses to vaccination for other diseases such as [[BCG vaccine|BCG]], [[measles]], and [[Hepatitis B]].<ref>{{Cite journal |last1=Natukunda |first1=Agnes |last2=Zirimenya |first2=Ludoviko |last3=Nassuuna |first3=Jacent |last4=Nkurunungi |first4=Gyaviira |last5=Cose |first5=Stephen |last6=Elliott |first6=Alison M. |last7=Webb |first7=Emily L. |date=17 June 2022 |title=The effect of helminth infection on vaccine responses in humans and animal models: A systematic review and meta-analysis |journal=Parasite Immunology |language=en |volume=44 |issue=9 |pages=e12939 |doi=10.1111/pim.12939 |issn=0141-9838 |pmc=9542036 |pmid=35712983}}</ref>

==== Chronic illness ====
Chronic helminthiasis may cause severe [[morbidity]].<ref name="bar">{{Cite book |title=Medical Microbiology |vauthors=Baron S |publisher=Galveston (TX): The University of Texas Medical Branch at Galveston |year=1996 |isbn=978-0963117212 |edition=4 |chapter=87 (Helminths: Pathogenesis and Defenses by Wakelin D |pmid=21413312 |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK8191/}}</ref> Helminthiasis has been found to result in poor birth outcome, poor cognitive development, poor school and work performance, decreased productivity, poor socioeconomic development, and poverty.<ref name="who" /><ref name="books.google.com" /><ref name="WHO2012" />

====Malnutrition====
Helminthiasis may cause chronic illness through malnutrition including [[vitamin deficiencies]], [[stunted growth]], [[anemia]], and [[protein-energy malnutrition]]. Worms compete directly with their hosts for nutrients, but the magnitude of this effect is likely minimal as the nutritional requirements of worms is relatively small.<ref name="Lev" /><ref name="WB" /><ref name="Wat" /> In pigs and humans, ''Ascaris'' has been linked to [[lactose intolerance]] and [[vitamin A]], [[amino acid]], and fat [[malabsorption]].<ref name="who" /> Impaired nutrient uptake may result from direct damage to the intestinal mucosal wall or from more subtle changes such as chemical imbalances and changes in gut flora.<ref>Crompton, D. W. T. (1993). [https://books.google.com/books?id=oT6BrfK7XQYC&dq=crompton%20Human%20Nutrition%20and%20Parasitic%20Infection.&pg=PA5202 Human Nutrition and Parasitic Infection]. Cambridge University Press.</ref> Alternatively, the worms’ release of [[protease inhibitors]] to defend against the body's digestive processes may impair the breakdown of other nutrients.<ref name="Lev">{{Cite book |url=http://pdf.usaid.gov/pdf_docs/PNABQ180.pdf |archive-url=https://web.archive.org/web/20110718111936/http://pdf.usaid.gov/pdf_docs/PNABQ180.pdf |url-status=dead |archive-date=July 18, 2011 |title=Nutrition, Health, and Learning: Current Issues and Trends |vauthors=Levinger B |date=1992 |series=School Nutrition and Health Network Monograph Series, #1. |quote=Please note that this estimate is less current than the Watkins and Pollitt estimate, leading Levinger to underestimate the number infected.}}</ref><ref name="Wat">{{Cite journal |vauthors=Watkins WE, Pollitt E |date=March 1997 |title="Stupidity or worms": do intestinal worms impair mental performance? |journal=Psychological Bulletin |volume=121 |issue=2 |pages=171–91 |doi=10.1037/0033-2909.121.2.171 |pmid=9100486}}</ref> In addition, worm induced diarrhoea may shorten gut transit time, thus reducing absorption of nutrients.<ref name="who" />

Malnutrition due to worms can give rise to [[Anorexia (symptom)|anorexia]].<ref name="WB">{{Cite web |last=The World Bank |title=World Development Report 1993: Investing in Health |url=http://files.dcp2.org/pdf/WorldDevelopmentReport1993.pdf |url-status=dead |archive-url=https://web.archive.org/web/20140225050318/http://files.dcp2.org/pdf/WorldDevelopmentReport1993.pdf |archive-date=2014-02-25 |access-date=2014-10-21}}</ref> A study of 459 children in [[Zanzibar]] revealed spontaneous increases in appetite after [[deworming]].<ref>{{Cite journal |name-list-style=vanc |vauthors=Stoltzfus RJ, Chway HM, Montresor A, Tielsch JM, Jape JK, Albonico M, Savioli L |date=February 2004 |title=Low dose daily iron supplementation improves iron status and appetite but not anemia, whereas quarterly anthelminthic treatment improves growth, appetite and anemia in Zanzibari preschool children |journal=The Journal of Nutrition |volume=134 |issue=2 |pages=348–56 |doi=10.1093/jn/134.2.348 |pmid=14747671 |doi-access=free}}</ref> Anorexia might be a result of the body's immune response and the stress of combating infection.<ref name="Wat" /> Specifically, some of the [[cytokines]] released in the immune response to worm infestation have been linked to anorexia in animals.<ref name="Lev" />

====Anemia====
Helminths may cause [[iron-deficiency anemia]]. This is most severe in heavy [[hookworm infection]]s, as ''[[Necator americanus]]'' and ''[[Ancylostoma duodenale]]'' feed directly on the blood of their hosts. Although the daily consumption of an individual worm (0.02–0.07 ml and 0.14–0.26 ml respectively) is small, the collective consumption under heavy infection can be clinically significant.<ref name="who" /><ref name="Wat" /> Intestinal [[whipworm]] may also cause anemia. Anemia has also been associated with reduced stamina for physical labor, a decline in the ability to learn new information, and apathy, irritability, and fatigue.<ref name="who" /> A study of the effect of deworming and iron supplementation in 47 students from the [[Democratic Republic of the Congo]] found that the intervention improved cognitive function.<ref name="Bov">{{Cite journal |vauthors=Boivin MJ, Giordani B |date=April 1993 |title=Improvements in cognitive performance for schoolchildren in Zaire, Africa, following an iron supplement and treatment for intestinal parasites |url=http://jpepsy.oxfordjournals.org/cgi/reprint/18/2/249 |journal=Journal of Pediatric Psychology |volume=18 |issue=2 |pages=249–64 |doi=10.1093/jpepsy/18.2.249 |pmid=8492277 |id=2|url-access=subscription }}</ref> Another study found that in 159 [[Jamaica]]n schoolchildren, deworming led to better auditory [[short-term memory]] and scanning and retrieval of [[long-term memory]] over a period of nine-weeks.<ref name="Nok">{{Cite journal |vauthors=Nokes C, Grantham-McGregor SM, Sawyer AW, Cooper ES, Bundy DA |date=February 1992 |title=Parasitic helminth infection and cognitive function in school children |journal=Proceedings. Biological Sciences |volume=247 |issue=1319 |pages=77–81 |bibcode=1992RSPSB.247...77N |doi=10.1098/rspb.1992.0011 |pmid=1349184 |s2cid=22199934}}</ref>

====Cognitive changes====
Malnutrition due to helminths may affect cognitive function leading to low educational performance, decreased concentration and difficulty with abstract cognitive tasks. Iron deficiency in infants and preschoolers is associated with "lower scores ... on tests of mental and motor development ... [as well as] increased fearfulness, inattentiveness, and decreased social responsiveness".<ref name="Lev" /> Studies in the Philippines and Indonesia found a significant correlation between helminthiasis and decreased memory and fluency.<ref>{{Cite journal |display-authors=6 |name-list-style=vanc |vauthors=Ezeamama AE, Friedman JF, Acosta LP, Bellinger DC, Langdon GC, Manalo DL, Olveda RM, Kurtis JD, McGarvey ST |date=May 2005 |title=Helminth infection and cognitive impairment among Filipino children |journal=The American Journal of Tropical Medicine and Hygiene |volume=72 |issue=5 |pages=540–548 |doi=10.4269/ajtmh.2005.72.540 |pmc=1382476 |pmid=15891127}}</ref><ref>{{Cite journal |vauthors=Sakti H, Nokes C, Hertanto WS, Hendratno S, Hall A, Bundy DA |date=May 1999 |title=Evidence for an association between hookworm infection and cognitive function in Indonesian school children |url=http://www3.interscience.wiley.com/cgi-bin/fulltext/119090322/PDFSTART |journal=Tropical Medicine & International Health |volume=4 |issue=5 |pages=322–34 |doi=10.1046/j.1365-3156.1999.00410.x |pmid=10402967 |s2cid=16553760|doi-access=free }}{{dead link|date=February 2019|bot=medic}}{{cbignore|bot=medic}}</ref> Large parasite burdens, particularly severe hookworm infections, are also associated with [[absenteeism]], under-enrollment, and attrition in school children.<ref name="Lev" />

==Transmission==
Helminths are transmitted to the [[definitive host|final host]] in several ways. The most common infection is through [[ingestion]] of contaminated vegetables, drinking water, and raw or undercooked meat. Contaminated food may contain eggs of nematodes such as ''Ascaris'', ''Enterobius'', and ''Trichuris''; cestodes such as ''Taenia'', ''Hymenolepis'', and ''Echinococcus''; and trematodes such as ''Fasciola''. Raw or undercooked meats are the major sources of ''Taenia'' (pork, beef and venison), ''Trichinella'' (pork and bear), ''Diphyllobothrium'' (fish), ''Clonorchis'' (fish), and ''Paragonimus'' (crustaceans). Schistosomes and nematodes such as hookworms (''Ancylostoma'' and ''Necator'') and ''Strongyloides'' can penetrate the skin directly.<ref name="bar" />

The roundworm, ''Dracunculus'' has a complex mode of transmission: it is acquired from drinking infested water or eating frogs and fish that contain (had eaten) infected crustaceans ([[copepods]]); and can also be transmitted from infected pets (cats and dogs).<ref>{{cite journal | vauthors = Galán-Puchades MT | title = Dracunculiasis: water-borne anthroponosis vs. food-borne zoonosis | journal = Journal of Helminthology | volume = 94 | pages = e76 | date = August 2019 | pmid = 31434586 | doi = 10.1017/S0022149X19000713 | s2cid = 201274949 | hdl = 10550/104649 | hdl-access = free }}</ref> Roundworms such as ''Brugia'', ''Wuchereria and'' ''Onchocerca'' are directly [[Mosquito-borne disease|transmitted by mosquitoes]].<ref>{{cite journal | vauthors = Pilotte N, Unnasch TR, Williams SA | title = The Current Status of Molecular Xenomonitoring for Lymphatic Filariasis and Onchocerciasis | journal = Trends in Parasitology | volume = 33 | issue = 10 | pages = 788–798 | date = October 2017 | pmid = 28756911 | doi = 10.1016/j.pt.2017.06.008 }}</ref><ref>{{cite journal | vauthors = Nanduri J, Kazura JW | title = Clinical and laboratory aspects of filariasis | journal = Clinical Microbiology Reviews | volume = 2 | issue = 1 | pages = 39–50 | date = January 1989 | pmid = 2644023 | pmc = 358099 | doi = 10.1128/CMR.2.1.39 }}</ref> In the developing world, the use of contaminated water is a major risk factor for infection.<ref name="Charity Water">{{Cite web |year=2009 |title=Contaminated drinking water |url=http://www.charitywater.org/whywater |website=Charity Water |vauthors=Harrison S, Deng A, Green B, Gorder C, Goodman MZ}}{{verify source|date=July 2022|reason=Did not find article}}</ref> Infection can also take place through the practice of [[geophagy]], which is not uncommon in parts of [[sub-Saharan Africa]]. Soil is eaten, for example, by children or pregnant women to counteract a real or perceived deficiency of minerals in their diet.<ref name="obi">{{Cite journal |vauthors=Bisi-Johnson MA, Obi CL, Ekosse GE |date=2010 |title=Microbiological and health related perspectives of geophagia: an overview |url=http://www.ajol.info/index.php/ajb/article/download/92778/82208 |journal=African Journal of Biotechnology |volume=9 |issue=36 |pages=5784–91}}</ref>

==Diagnosis==
[[File:Identification and quantification of helminth eggs.png|thumb|Identification and quantification of helminth eggs at UNAM university in Mexico City, Mexico]]

Specific helminths can be identified through [[microscopy|microscopic]] examination of their eggs (ova) found in faecal samples. The number of eggs is measured in units of [[eggs per gram]].<ref name=crom/> However, it does not quantify [[coinfection|mixed infection]]s, and in practice, is inaccurate for quantifying the eggs of schistosomes and soil-transmitted helminths.<ref>{{Cite journal |vauthors=Krauth SJ, Coulibaly JT, Knopp S, Traoré M, N'Goran EK, Utzinger J |year=2012 |title=An in-depth analysis of a piece of shit: distribution of Schistosoma mansoni and hookworm eggs in human stool |journal=PLOS Neglected Tropical Diseases |volume=6 |issue=12 |pages=e1969 |doi=10.1371/journal.pntd.0001969 |pmc=3527364 |pmid=23285307 |doi-access=free }}</ref> Sophisticated tests such as [[serology|serological assay]]s, [[antigen test]]s, and [[genetic testing|molecular diagnosis]] are also available;<ref name=crom/><ref name=lus/> however, they are time-consuming, expensive and not always reliable.<ref>{{Cite journal |vauthors=Hunt PW, Lello J |date=May 2012 |title=How to make DNA count: DNA-based diagnostic tools in veterinary parasitology |journal=Veterinary Parasitology |volume=186 |issue=1–2 |pages=101–8 |doi=10.1016/j.vetpar.2011.11.055 |pmid=22169224}}</ref>

==Prevention==
Disrupting the cycle of the worm will prevent infestation and re-infestation. Prevention of infection can largely be achieved by addressing the issues of [[WASH]]—water, [[sanitation]] and [[hygiene]].<ref>{{Cite web |title=Water, Sanitation & Hygiene: Strategy Overview |url=http://www.gatesfoundation.org/What-We-Do/Global-Development/Water-Sanitation-and-Hygiene |url-status=dead |archive-url=https://web.archive.org/web/20171107060749/http://www.gatesfoundation.org/What-We-Do/Global-Development/Water-Sanitation-and-Hygiene |archive-date=7 November 2017 |access-date=27 April 2015 |website=Bill & Melinda Gates Foundation}}</ref><ref>{{Cite web |title=Water, Sanitation, and Hygiene: Introduction |url=http://www.unicef.org/wash/index_3951.html |url-status=dead |archive-url=https://web.archive.org/web/20150424221052/http://www.unicef.org/wash/index_3951.html |archive-date=24 April 2015 |access-date=27 April 2015 |website=UNICEF }}</ref><ref>{{Cite web |title=Goal 7: Ensure Environmental Sustainability |url=https://www.un.org/millenniumgoals/environ.shtml |access-date=27 April 2015 |website=United Nations Millennium Development Goals website}}</ref> The reduction of [[open defecation]] is particularly called for,<ref name="HalesZiegelbauer2012">{{Cite journal |vauthors=Ziegelbauer K, Speich B, Mäusezahl D, Bos R, Keiser J, Utzinger J |date=January 2012 |title=Effect of sanitation on soil-transmitted helminth infection: systematic review and meta-analysis |journal=PLOS Medicine |volume=9 |issue=1 |pages=e1001162 |doi=10.1371/journal.pmed.1001162 |pmc=3265535 |pmid=22291577 |doi-access=free }}</ref><ref name="Strunz2014">{{Cite journal |vauthors=Strunz EC, Addiss DG, Stocks ME, Ogden S, Utzinger J, Freeman MC |date=March 2014 |title=Water, sanitation, hygiene, and soil-transmitted helminth infection: a systematic review and meta-analysis |journal=PLOS Medicine |volume=11 |issue=3 |pages=e1001620 |doi=10.1371/journal.pmed.1001620 |pmc=3965411 |pmid=24667810 |doi-access=free }}</ref> as is stopping the use of [[human waste]] as [[fertilizer]].<ref name=WHO2015/>

Further preventive measures include adherence to appropriate [[food hygiene]], wearing of shoes, regular [[deworming]] of pets, and the proper disposal of their feces.<ref name="who" />

Scientists are also searching for a vaccine against helminths, such as a [[hookworm vaccine]].<ref name="HotezDiemert2013">{{Cite journal |display-authors=6 |vauthors=Hotez PJ, Diemert D, Bacon KM, Beaumier C, Bethony JM, Bottazzi ME, Brooker S, Couto AR, Freire M, Homma A, Lee BY, Loukas A, Loblack M, Morel CM, Oliveira RC, Russell PK |date=April 2013 |title=The Human Hookworm Vaccine |journal=Vaccine |volume=31 |issue=Suppl 2 |pages=B227-32 |doi=10.1016/j.vaccine.2012.11.034 |pmc=3988917 |pmid=23598487}}</ref>

==Treatment==

=== Medications ===
{{Main|Anthelmintic}}
Broad-spectrum [[benzimidazoles]] (such as [[albendazole]] and [[mebendazole]]) are the first line treatment of intestinal [[nematoda|roundworm]] and [[cestoda|tapeworm]] infections. Macrocyclic lactones (such as [[ivermectin]]) are effective against adult and migrating larval stages of nematodes. [[Praziquantel]] is the drug of choice for schistosomiasis, taeniasis, and most types of food-borne trematodiases. [[Oxamniquine]] is also widely used in mass deworming programmes. [[Pyrantel]] is commonly used for veterinary nematodiasis.<ref>{{Cite web |title=Anthelmintics |url=https://www.drugs.com/drug-class/anthelmintics.html |access-date=17 November 2014 |website=Drugs.com}}</ref><ref>{{Cite web |title=Overview of Anthelmintics |url=http://www.merckmanuals.com/vet/pharmacology/anthelmintics/overview_of_anthelmintics.html |access-date=17 November 2014 |website=The Merck Veterinary Manual |publisher=Merck Sharp & Dohme Corp.}}</ref> [[Artemisinin]]s and derivatives are proving to be candidates as drugs of choice for trematodiasis.<ref>{{Cite journal |vauthors=Pérez del Villar L, Burguillo FJ, López-Abán J, Muro A |date=2012 |title=Systematic review and meta-analysis of artemisinin based therapies for the treatment and prevention of schistosomiasis |journal=PLOS ONE |volume=7 |issue=9 |pages=e45867 |bibcode=2012PLoSO...745867P |doi=10.1371/journal.pone.0045867 |pmc=3448694 |pmid=23029285 |doi-access=free}}</ref>

=== Mass deworming ===
{{Main|Mass deworming}}
In [[endemic (epidemiology)|regions where helminthiasis is common]], mass deworming treatments may be performed, particularly among school-age children, who are a high-risk group.<ref>{{Cite book |last=WHO |url=http://whqlibdoc.who.int/publications/2006/9241547103_eng.pdf |title=Preventive chemotherapy in human helminthiasis: coordinated use of anthelminthic drugs in control interventions: a manual for health professionals and programme managers |publisher=WHO Press, World Health Organization, Geneva, Switzerland |year=2006 |isbn=978-9241547109 |pages=1–61}}</ref><ref>{{Cite journal |display-authors=6 |vauthors=Prichard RK, Basáñez MG, Boatin BA, McCarthy JS, García HH, Yang GJ, Sripa B, Lustigman S |year=2012 |title=A research agenda for helminth diseases of humans: intervention for control and elimination |journal=PLOS Neglected Tropical Diseases |volume=6 |issue=4 |pages=e1549 |doi=10.1371/journal.pntd.0001549 |pmc=3335868 |pmid=22545163 |doi-access=free }}</ref> Most of these initiatives are undertaken by the [[World Health Organization]] (WHO) with positive outcomes in many regions.<ref>{{Cite journal |vauthors=Bundy DA, Walson JL, Watkins KL |date=March 2013 |title=Worms, wisdom, and wealth: why deworming can make economic sense |journal=Trends in Parasitology |volume=29 |issue=3 |pages=142–8 |doi=10.1016/j.pt.2012.12.003 |pmid=23332661}}</ref><ref>{{Cite journal |vauthors=Albonico M, Allen H, Chitsulo L, Engels D, Gabrielli AF, Savioli L |date=March 2008 |title=Controlling soil-transmitted helminthiasis in pre-school-age children through preventive chemotherapy |journal=PLOS Neglected Tropical Diseases |volume=2 |issue=3 |pages=e126 |doi=10.1371/journal.pntd.0000126 |pmc=2274864 |pmid=18365031 |doi-access=free }}</ref> Deworming programs can improve school attendance by 25 percent.<ref name="Miguel">{{Cite journal |vauthors=Miguel E, Kremer M |year=2004 |title=Worms: Identifying Impacts on Education and Health in the Presence of Treatment Externalities |journal=Econometrica |volume=72 |issue=1 |pages=159–217 |citeseerx=10.1.1.336.7123 |doi=10.1111/j.1468-0262.2004.00481.x}}</ref> Although deworming improves the health of an individual, outcomes from [[mass deworming]] campaigns, such as reduced deaths or increases in cognitive ability, nutritional benefits, physical growth, and performance, are uncertain or not apparent.<ref>{{Cite web |date=2015-08-04 |title=Economist, World Bank |url=http://blogs.worldbank.org/impactevaluations/worm-wars-anthology |access-date=5 August 2015 |website=Development Impact blog, World Bank |publisher=World Bank |vauthors=Evans D}}</ref><ref>{{Cite journal |vauthors=Hawkes N |date=January 2012 |title=Deworming debunked |journal=BMJ |volume=346 |issue=jan02 1 |pages=e8558 |doi=10.1136/bmj.e8558 |pmid=23284157 |s2cid=5568263|doi-access=free }}</ref><ref>{{Cite journal |vauthors=Taylor-Robinson DC, Maayan N, Donegan S, Chaplin M, Garner P |date=September 2019 |title=Public health deworming programmes for soil-transmitted helminths in children living in endemic areas |journal=The Cochrane Database of Systematic Reviews |volume=9 |issue=11 |pages=CD000371 |doi=10.1002/14651858.CD000371.pub7 |pmc=6737502 |pmid=31508807}}</ref><ref>{{Cite journal |vauthors=Ahuja A, Baird S, Hicks JH, Kremer M, Miguel E, Powers S |date=2015 |title=When Should Governments Subsidize Health? The Case of Mass Deworming |journal=The World Bank Economic Review |volume=29 |issue=suppl 1 |pages=S9–S24 |doi=10.1093/wber/lhv008 |doi-access=free}}</ref>

=== Surgery ===
[[File:Ascaris infection- Difficult intestinal anastamosis - joining up of two ends- clearly if we cut out a section of bowel we're left with two ends that need to be joined up (South Africa) (15806559973).jpg|thumb|Example of [[ascariasis]] (ascaris infection) - Difficult surgical procedure in South Africa on a gangrenous piece of bowel that had to be cut out; live ascaris worms are emerging.]]
[[File:Piece of intestine, blocked by worms (16424898321).jpg|thumb|Piece of intestine, blocked by worms, surgically removed from a 3-year-old boy in South Africa.<ref name="susana.org">Fincham, J., Dhansay, A. (2006). [http://www.susana.org/en/resources/library/details/2110 Worms in SA's children - MRC Policy Brief]. Nutritional Intervention Research Unit of the South African Medical Research Council, South Africa</ref>]]

If complications of helminthiasis, such as [[intestinal obstruction]] occur, emergency surgery may be required.<ref name=":9" /><ref name="susana.org" /> Patients who require non-emergency surgery, for instance for removal of worms from the [[biliary tree]], can be pre-treated with the anthelmintic drug albendazole.<ref name=":9" />

==Epidemiology==
Areas with the highest prevalence of helminthiasis are [[tropics|tropical]] and [[subtropics|subtropical]] areas including sub-Saharan Africa, central and east Asia, and the Americas.{{citation needed|date=January 2021}}

=== Neglected tropical diseases ===
Some types of helminthiases are classified as [[neglected tropical diseases]].<ref name="Neglected Tropical Diseases" /><ref>{{Cite web |title=Fact sheets: neglected tropical diseases |url=https://www.who.int/topics/tropical_diseases/factsheets/neglected/en |url-status=dead |archive-url=https://web.archive.org/web/20110124092537/http://www.who.int/topics/tropical_diseases/factsheets/neglected/en/ |archive-date=January 24, 2011 |access-date=6 December 2014 |website=World Health Organization |publisher=WHO Media Centre}}</ref> They include:
* Soil-transmitted helminthiases
* Roundworm infections such as [[lymphatic filariasis]], dracunculiasis, and onchocerciasis
* Trematode infections, such as schistosomiasis, and food-borne trematodiases, including fascioliasis, clonorchiasis, opisthorchiasis, and paragonimiasis
* Tapeworm infections such as cysticercosis, taeniasis, and echinococcosis

=== Prevalence ===
The soil-transmitted helminths (''A. lumbricoides'', ''T. trichiura'', ''N. americanus'', ''A. duodenale)'', [[schistosoma|schistosomes]], and [[filarioidea|filarial worms]] collectively infect more than a quarter of the human population worldwide at any one time, far surpassing HIV and malaria together.<ref name="crom">{{Cite book |url=https://books.google.com/books?id=M6qOL15UlesC |title=Handbook of Helminthiasis for Public Health |vauthors=Crompton DW, Savioli L |publisher=CRC Press, Boca Raton, Florida, US |year=2007 |isbn=9781420004946 |pages=1–362}}</ref><ref name="lus">{{Cite journal |vauthors=Lustigman S, Prichard RK, Gazzinelli A, Grant WN, Boatin BA, McCarthy JS, Basáñez MG |year=2012 |title=A research agenda for helminth diseases of humans: the problem of helminthiases |journal=PLOS Neglected Tropical Diseases |volume=6 |issue=4 |pages=e1582 |doi=10.1371/journal.pntd.0001582 |pmc=3335854 |pmid=22545164 |doi-access=free }}</ref> [[Schistosomiasis]] is the second most prevalent parasitic disease of humans after malaria.<ref>{{Cite book |last=WHO |title=Schistosomiasis: progress report 2001 - 2011, strategic plan 2012 - 2020 |publisher=WHO Press, World Health Organization, Geneva, Switzerland |year=2013 |isbn=9789241503174 |pages=1–270 |hdl=10665/78074?mode=full}}</ref>

In 2014–15, the WHO estimated that approximately 2 billion people were infected with soil-transmitted helminthiases,<ref name=WHO2015/> 249 million with schistosomiasis,<ref>{{Cite web |date=May 2015 |title=Malaria |url=https://www.who.int/mediacentre/factsheets/fs094/en |url-status=dead |archive-url=https://web.archive.org/web/20040614022014/http://www.who.int/mediacentre/factsheets/fs094/en/ |archive-date=June 14, 2004 |access-date=7 February 2016 |website=Fact sheet N°94 |publisher=WHO Media Centre}}</ref> 56 million people with food-borne trematodiasis,<ref>{{Cite web |date=2014 |title=Foodborne trematode infections |url=https://www.who.int/foodborne_trematode_infections/en |access-date=7 February 2016 |website=Factsheet N°368 |publisher=WHO Media Centre}}</ref> 120 million with lymphatic filariasis,<ref>{{Cite web |date=May 2015 |title=Lymphatic filariasis |url=https://www.who.int/mediacentre/factsheets/fs102/en |url-status=dead |archive-url=https://web.archive.org/web/20040502123722/http://www.who.int/mediacentre/factsheets/fs102/en/ |archive-date=May 2, 2004 |access-date=7 February 2016 |website=Fact sheet N°102 |publisher=WHO Media centre}}</ref> 37 million people with onchocerciasis,<ref name="WHOOnc">{{Cite web |date=March 2014 |title=A global brief on vector-borne diseases |url=http://apps.who.int/iris/bitstream/10665/111008/1/WHO_DCO_WHD_2014.1_eng.pdf?ua=1 |access-date=8 March 2016 |publisher=World Health Organization |page=22}}</ref> and 1 million people with echinococcosis.<ref>{{Cite web |date=May 2015 |title=Echinococcosis |url=https://www.who.int/mediacentre/factsheets/fs377/en |url-status=dead |archive-url=https://web.archive.org/web/20140221184309/http://www.who.int/mediacentre/factsheets/fs377/en/ |archive-date=February 21, 2014 |access-date=7 February 2016 |website=Fact sheet N°377 |publisher=WHO Media Centre}}</ref> Another source estimated a much higher figure of 3.5 billion infected with one or more soil-transmitted helminths.<ref name="OjhaJaide2014">{{Cite journal |vauthors=Ojha SC, Jaide C, Jinawath N, Rotjanapan P, Baral P |date=January 2014 |title=Geohelminths: public health significance |url=http://jidc.org/index.php/journal/article/download/24423707/975 |journal=Journal of Infection in Developing Countries |volume=8 |issue=1 |pages=5–16 |doi=10.3855/jidc.3183 |pmid=24423707 |doi-access=free}}</ref><ref>Velleman, Y., Pugh, I. (2013). [http://www.susana.org/en/resources/library/details/1794 Under-nutrition and water, sanitation and hygiene - Water, sanitation and hygiene (WASH) play a fundamental role in improving nutritional outcomes. A successful global effort to tackle under-nutrition must include WASH]. WaterAid and Share, UK</ref>

In 2014, only 148 people were reported to have [[dracunculiasis]] because of a successful eradication campaign for that particular helminth, which is easier to eradicate than other helminths as it is transmitted only by drinking contaminated water.<ref>{{Cite web |date=March 2014 |title=Dracunculiasis (guinea-worm disease) |url=https://www.who.int/mediacentre/factsheets/fs359/en |url-status=dead |archive-url=https://web.archive.org/web/20130730230030/http://www.who.int/mediacentre/factsheets/fs359/en/ |archive-date=July 30, 2013 |access-date=6 December 2014 |website=Fact sheet N°359 (Revised) |publisher=WHO Media Centre}}</ref>

Because of their high mobility and lower standards of hygiene, school-age children are particularly vulnerable to helminthiasis.<ref name="MONTRESS">{{Cite book |url=https://www.who.int/wormcontrol/documents/en/001to011.pdf |title=Helminth Control in School-Age Children: A Guide for Managers of Control Programs |vauthors=Montresor A, Crompton W, ((World Health Organization)), Gyorkos TW, Savioli L |publisher=World Health Organization |year=2002 |isbn=9789241545563 |archive-url=https://web.archive.org/web/20040718002440/https://www.who.int/wormcontrol/documents/en/001to011.pdf |archive-date=18 July 2004}}</ref> Most children from developing nations will have at least one infestation. Multi-species infections are very common.<ref>{{Cite journal |vauthors=Bethony J, Brooker S, Albonico M, Geiger SM, Loukas A, Diemert D, Hotez PJ |date=May 2006 |title=Soil-transmitted helminth infections: ascariasis, trichuriasis, and hookworm |journal=Lancet |volume=367 |issue=9521 |pages=1521–32 |doi=10.1016/S0140-6736(06)68653-4 |pmid=16679166 |s2cid=8425278}}</ref>

The most common intestinal parasites in the United States are ''[[Enterobius vermicularis]]'', ''[[Giardia lamblia]]'', ''[[Ancylostoma duodenale]]'', ''[[Necator americanus]]'', and ''[[Entamoeba histolytica]]''.<ref name="pmid15023017">{{Cite journal |vauthors=Kucik CJ, Martin GL, Sortor BV |date=March 2004 |title=Common intestinal parasites |url=https://pubmed.ncbi.nlm.nih.gov/15023017 |journal=American Family Physician |volume=69 |issue=5 |pages=1161–8 |pmid=15023017}}</ref>

In a developing country like Bangladesh, the most common species are round worm (''[[Ascaris lumbricoides]]''), whipworm (Tricurias tricuras) and hookworm
(Ancylostoma duodenalis).<ref>{{cite journal | url=https://www.ajol.info/index.php/sajchh/article/view/73423 | title=Patterns and risk factors for helminthiasis in rural children aged under 2 in Bangladesh | journal=South African Journal of Child Health | date=2011 | volume=5 | issue=3 | pages=78–84 | last1=Roy | first1=E. | last2=Hasan | first2=K. Z. | last3=Haque | first3=R. | last4=Haque | first4=Akmf | last5=Siddique | first5=A. K. | last6=Sack | first6=R. B. }}</ref>

=== Variations within communities ===
Even in areas of high prevalence, the frequency and severity of infection is not uniform within communities or families.<ref name="Magill">{{Cite book |title=Hunter's tropical medicine and emerging infectious diseases |vauthors=Magill AJ, Hill DR, Solomon T, Ryan ET |date=2013 |publisher=Saunders |isbn=978-1-4160-4390-4 |edition=9th |location=New York |page=804}}</ref> A small proportion of community members harbour the majority of worms, and this depends on age. The maximum worm burden is at five to ten years of age, declining rapidly thereafter.<ref name=":11">{{Cite book |title=Hunter's tropical medicine and emerging infectious diseases |vauthors=Magill A |date=2013 |publisher=Saunders |isbn=978-1-4160-4390-4 |edition=9th |location=New York |page=804}}</ref> Individual predisposition to helminthiasis for people with the same sanitation infrastructure and hygiene behavior is thought to result from differing [[immunocompetence]], [[Human nutrition|nutritional status]], and [[Heredity|genetic factors]].<ref name=Magill/> Because individuals are predisposed to a high or a low worm burden, the burden reacquired after successful treatment is proportional to that before treatment.<ref name=Magill/>

=== Disability-adjusted life years ===
It is estimated that intestinal nematode infections cause 5 million [[disability-adjusted life years]] (DALYS) to be lost, of which hookworm infections account for more than 3 million DALYS and ascaris infections more than 1 million.<ref name="de SilvaHotez2014">{{cite journal | vauthors = Hotez PJ, Alvarado M, Basáñez MG, Bolliger I, Bourne R, Boussinesq M, Brooker SJ, Brown AS, Buckle G, Budke CM, Carabin H, Coffeng LE, Fèvre EM, Fürst T, Halasa YA, Jasrasaria R, Johns NE, Keiser J, King CH, Lozano R, Murdoch ME, O'Hanlon S, Pion SD, Pullan RL, Ramaiah KD, Roberts T, Shepard DS, Smith JL, Stolk WA, Undurraga EA, Utzinger J, Wang M, Murray CJ, Naghavi M | display-authors = 6 | title = The global burden of disease study 2010: interpretation and implications for the neglected tropical diseases | journal = PLOS Neglected Tropical Diseases | volume = 8 | issue = 7 | pages = e2865 | date = July 2014 | pmid = 25058013 | pmc = 4109880 | doi = 10.1371/journal.pntd.0002865 | doi-access = free }}</ref> There are also signs of progress: The [[Global Burden of Disease Study]] published in 2015 estimates a 46 percent (59 percent when age standardised) reduction in [[Disability-adjusted life year|years lived with disability]] (YLD) for the 13-year time period from 1990 to 2013 for all intestinal/nematode infections, and even a 74 percent (80 percent when age standardised) reduction in YLD from ascariasis.<ref>{{cite journal | title = Global, regional, and national incidence, prevalence, and years lived with disability for 301 acute and chronic diseases and injuries in 188 countries, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013 | journal = Lancet | volume = 386 | issue = 9995 | pages = 743–800 | date = August 2015 | pmid = 26063472 | pmc = 4561509 | doi = 10.1016/S0140-6736(15)60692-4 | last1 = Vos | first1 = Theo | last2 = Barber | first2 = Ryan M. | last3 = Bell | first3 = Brad | last4 = Bertozzi-Villa | first4 = Amelia | last5 = Biryukov | first5 = Stan | last6 = Bolliger | first6 = Ian | last7 = Charlson | first7 = Fiona | last8 = Davis | first8 = Adrian | last9 = Degenhardt | first9 = Louisa | last10 = Dicker | first10 = Daniel | last11 = Duan | first11 = Leilei | last12 = Erskine | first12 = Holly | last13 = Feigin | first13 = Valery L. | last14 = Ferrari | first14 = Alize J. | last15 = Fitzmaurice | first15 = Christina | last16 = Fleming | first16 = Thomas | last17 = Graetz | first17 = Nicholas | last18 = Guinovart | first18 = Caterina | last19 = Haagsma | first19 = Juanita | last20 = Hansen | first20 = Gillian M. | last21 = Hanson | first21 = Sarah Wulf | last22 = Heuton | first22 = Kyle R. | last23 = Higashi | first23 = Hideki | last24 = Kassebaum | first24 = Nicholas | last25 = Kyu | first25 = Hmwe | last26 = Laurie | first26 = Evan | last27 = Liang | first27 = Xiofeng | last28 = Lofgren | first28 = Katherine | last29 = Lozano | first29 = Rafael | last30 = MacIntyre | first30 = Michael F. | display-authors = 1 }}</ref>

===Deaths===
As many as 135,000 die annually from soil transmitted helminthiasis.<ref name="who" /><ref name="lus" /><ref name="yap">{{Cite journal |vauthors=Yap P, Fürst T, Müller I, Kriemler S, Utzinger J, Steinmann P |date=August 2012 |title=Determining soil-transmitted helminth infection status and physical fitness of school-aged children |journal=Journal of Visualized Experiments |volume=66 |issue=66 |pages=e3966 |doi=10.3791/3966 |pmc=3486755 |pmid=22951972}}</ref>

The 1990–2013 [[Global Burden of Disease Study]] estimated 5,500 direct deaths from schistosomiasis,<ref>{{Cite journal | vauthors = Naghavi M, Wang H, Lozano R, Davis A, Liang X, Zhou M, etal |date=January 2015 |title=Global, regional, and national age-sex specific all-cause and cause-specific mortality for 240 causes of death, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013 |journal=Lancet |volume=385 |issue=9963 |pages=117–171 |doi=10.1016/S0140-6736(14)61682-2 |pmc=4340604 |pmid=25530442 |hdl=11655/15525 |collaboration=GBD 2013 Mortality Causes of Death Collaborators}}</ref> while more than 200,000 people were estimated in 2013 to die annually from causes related to schistosomiasis.<ref name="The2013">{{Cite journal |vauthors=Thétiot-Laurent SA, Boissier J, Robert A, Meunier B |date=July 2013 |title=Schistosomiasis chemotherapy |journal=Angewandte Chemie |volume=52 |issue=31 |pages=7936–56 |doi=10.1002/anie.201208390 |pmid=23813602}}</ref> Another 20 million have severe consequences from the disease.<ref>{{Cite journal |vauthors=Kheir MM, Eltoum IA, Saad AM, Ali MM, Baraka OZ, Homeida MM |date=February 1999 |title=Mortality due to schistosomiasis mansoni: a field study in Sudan |journal=The American Journal of Tropical Medicine and Hygiene |volume=60 |issue=2 |pages=307–10 |doi=10.4269/ajtmh.1999.60.307 |pmid=10072156 |doi-access=free}}</ref> It is the most deadly of the neglected tropical diseases.<ref name="CDC2011">{{Cite web |date=6 June 2011 |title=Neglected Tropical Diseases |url=https://www.cdc.gov/globalhealth/ntd/diseases/schisto_burden.html |access-date=28 November 2014 |website=cdc.gov}}</ref>

{| class="wikitable"
!Helminth genera
!Common name
! width=20% |Infections (million per year)
! width=20% |Direct deaths per year
!Regions where common
|-
| colspan="5" |[[Soil transmitted helminthiasis]] (STH) (classified as [[neglected tropical disease]]):
|-
| ''[[Ascaris lumbricoides]]''
| [[Roundworm]]
| 1000 to 1450
807 to 1,121<ref name=":8">{{Cite web |date=10 January 2013 |title=Parasites – Soil-transmitted Helminths (STHs) |url=https://www.cdc.gov/parasites/sth/index.html |access-date=20 December 2014 |publisher=Centers for Disease Control and Prevention (CDC)}}</ref>
| 20,000
| Many regions of South-east Asia, Africa, and Central and South America<ref name="Jimenez2006">{{cite journal | vauthors = Jiménez B | title = Irrigation in developing countries using wastewater. | journal = International Review for Environmental Strategies. | date = March 2006 | volume = 6 | issue = 2 | pages = 229–50 | url = https://www.iges.or.jp/en/publication_documents/pub/peer/en/1199/IRES_Vol.6-2_229.pdf }}</ref><ref name=":1">{{cite journal | vauthors = Jimenez B | title = Helminth ova removal from wastewater for agriculture and aquaculture reuse | journal = Water Science and Technology | volume = 55 | issue = 1–2 | pages = 485–493 | date = 2007 | pmid = 17305174 | doi = 10.2166/wst.2007.046 | doi-access = free | bibcode = 2007WSTec..55..485J }}</ref><ref name=":2">{{cite journal | vauthors = Navarro I, Jiménez B, Lucario S, Cifuentes E | title = Application of Helminth ova infection dose curve to estimate the risks associated with biosolid application on soil | journal = Journal of Water and Health | volume = 7 | issue = 1 | pages = 31–44 | date = March 2009 | pmid = 18957773 | doi = 10.2166/wh.2009.113 | doi-access = free | bibcode = 2009JWH.....7...31N }}</ref><ref name=":3">{{cite book | vauthors = Jiménez B, Navarro I | chapter = Wastewater use in agriculture: public health considerations. | veditors = Jorgensen SE | title = Encyclopedia of Water Science | edition = 2nd | publisher = CRC Press | location = Boca Raton | date = 2007 | doi = 10.1201/9781351235860 |url=https://www.taylorfrancis.com/books/edit/10.1201/9781351235860/encyclopedia-environmental-management-sven-erik-jorgensen | chapter-url=https://www.taylorfrancis.com/chapters/edit/10.1081/E-EEM-120046689/wastewater-use-agriculture-public-health-considerations-blanca-jim%C3%A9nez-in%C3%A9s-navarro| isbn=9781351235860 | s2cid = 199087706 }}</ref><ref name=":4">{{cite book | vauthors = Connor R | chapter = Water for People Water for Life | chapter-url = http://unesdoc.unesco.org/images/0012/001295/129556e.pdf | title = The United Nations world water development report 2015: water for a sustainable world. | location = Barcelona, Spain | publisher = UNESCO publishing | date = March 2015 }}</ref><ref name=":5">{{cite book | author = WHO | date = 1995 | url = http://apps.who.int/medicinedocs/en/d/Jh2922e/ | title = WHO Model Prescribing Information: Drug Use in Parasitic Diseases | publisher = WHO | location = Geneva, Switzerland | archive-url = https://web.archive.org/web/20090508153040/http://apps.who.int/medicinedocs/en/d/Jh2922e/ | archive-date = 2009-05-08 }}</ref>
|-
| ''[[Trichuris trichiura]]''
| [[Whipworm]]
| 500
604–795<ref name=":8" />
|
| In moist, warm, tropical regions of Asia, Africa, Central and South America, and the Caribbean islands.<ref name=":2" /><ref name=":3" /><ref name=":4" /><ref name=":5" /><ref name=":6">WHO (2006). [http://www.susana.org/en/resources/library/details/1004 WHO Guidelines for the Safe Use of Wastewater, Excreta and Greywater – Volume IV: Excreta and greywater use in agriculture] {{Webarchive|url=https://web.archive.org/web/20141017235811/http://www.susana.org/en/resources/library/details/1004 |date=2014-10-17 }}. World Health Organization (WHO), Geneva, Switzerland</ref>
|-
| ''[[Ancylostoma duodenale]]''
| rowspan="2" |[[Hookworms|Hookworm]]
| rowspan="2" |900 to 1300
576–740 (hookworm in general)<ref>{{Cite web |date=2017-05-02 |title=Parasites – Hookworm |url=https://www.cdc.gov/parasites/hookworm/index.html |access-date=20 December 2014 |publisher=Centers for Disease Control and Prevention}}</ref>
|
| rowspan="2" |In tropical and subtropical countries (Sub-Saharan Africa)<ref name=":3" /><ref name=":6" />
|-
| ''[[Necator americanus]]''
|
|-
| ''[[Strongyloides stercoralis]]''
| [[Hookworm]], [[pinworm]]
| 50 to 100
| Thousands
| In moist rainy areas of the tropics and subtropics, in some areas of southern and eastern Europe and of the United States of America<ref name=":3" /><ref name=":4" />
|-
| All STH together
|
| 1500 to 2000<ref name="WHO2015" />
| 135,000<ref name="who" /><ref name="lus" /><ref name="yap" />
| Tropical and subtropical areas, in particular sub-Saharan Africa, the Americas, China and east Asia.<ref name="WHO2015" />
|-
| colspan="5" |Not transmitted via soil but classified as neglected tropical disease:
|-
| ''[[Schistosoma mansoni]]''
| [[Blood fluke]]
| All types of ''Schistosoma ''together:'' ''160 to 200
(210 "affected"<ref name="Fen2012">{{Cite journal |vauthors=Fenwick A |date=March 2012 |title=The global burden of neglected tropical diseases |journal=Public Health |volume=126 |issue=3 |pages=233–236 |doi=10.1016/j.puhe.2011.11.015 |pmid=22325616}}</ref>)
| rowspan="2" | 12,000<ref name="Loz2012">{{Cite journal |display-authors=6 |vauthors=Lozano R, Naghavi M, Foreman K, Lim S, Shibuya K, Aboyans V, Abraham J, Adair T, Aggarwal R, Ahn SY, Alvarado M, Anderson HR, Anderson LM, Andrews KG, Atkinson C, Baddour LM, Barker-Collo S, Bartels DH, Bell ML, Benjamin EJ, Bennett D, Bhalla K, Bikbov B, Bin Abdulhak A, Birbeck G, Blyth F, Bolliger I, Boufous S, Bucello C, Burch M, Burney P, Carapetis J, Chen H, Chou D, Chugh SS, Coffeng LE, Colan SD, Colquhoun S, Colson KE, Condon J, Connor MD, Cooper LT, Corriere M, Cortinovis M, de Vaccaro KC, Couser W, Cowie BC, Criqui MH, Cross M, Dabhadkar KC, Dahodwala N, De Leo D, Degenhardt L, Delossantos A, Denenberg J, Des Jarlais DC, Dharmaratne SD, Dorsey ER, Driscoll T, Duber H, Ebel B, Erwin PJ, Espindola P, Ezzati M, Feigin V, Flaxman AD, Forouzanfar MH, Fowkes FG, Franklin R, Fransen M, Freeman MK, Gabriel SE, Gakidou E, Gaspari F, Gillum RF, Gonzalez-Medina D, Halasa YA, Haring D, Harrison JE, Havmoeller R, Hay RJ, Hoen B, Hotez PJ, Hoy D, Jacobsen KH, James SL, Jasrasaria R, Jayaraman S, Johns N, Karthikeyan G, Kassebaum N, Keren A, Khoo JP, Knowlton LM, Kobusingye O, Koranteng A, Krishnamurthi R, Lipnick M, Lipshultz SE, Ohno SL, Mabweijano J, MacIntyre MF, Mallinger L, March L, Marks GB, Marks R, Matsumori A, Matzopoulos R, Mayosi BM, McAnulty JH, McDermott MM, McGrath J, Mensah GA, Merriman TR, Michaud C, Miller M, Miller TR, Mock C, Mocumbi AO, Mokdad AA, Moran A, Mulholland K, Nair MN, Naldi L, Narayan KM, Nasseri K, Norman P, O'Donnell M, Omer SB, Ortblad K, Osborne R, Ozgediz D, Pahari B, Pandian JD, Rivero AP, Padilla RP, Perez-Ruiz F, Perico N, Phillips D, Pierce K, Pope CA, Porrini E, Pourmalek F, Raju M, Ranganathan D, Rehm JT, Rein DB, Remuzzi G, Rivara FP, Roberts T, De León FR, Rosenfeld LC, Rushton L, Sacco RL, Salomon JA, Sampson U, Sanman E, Schwebel DC, Segui-Gomez M, Shepard DS, Singh D, Singleton J, Sliwa K, Smith E, Steer A, Taylor JA, Thomas B, Tleyjeh IM, Towbin JA, Truelsen T, Undurraga EA, Venketasubramanian N, Vijayakumar L, Vos T, Wagner GR, Wang M, Wang W, Watt K, Weinstock MA, Weintraub R, Wilkinson JD, Woolf AD, Wulf S, Yeh PH, Yip P, Zabetian A, Zheng ZJ, Lopez AD, Murray CJ, AlMazroa MA, Memish ZA |date=December 2012 |title=Global and regional mortality from 235 causes of death for 20 age groups in 1990 and 2010: a systematic analysis for the Global Burden of Disease Study 2010 |url=https://zenodo.org/record/2557786 |journal=Lancet |volume=380 |issue=9859 |pages=2095–128 |doi=10.1016/S0140-6736(12)61728-0 |pmid=23245604 |pmc=10790329 |hdl-access=free |s2cid=1541253 |hdl=10536/DRO/DU:30050819}}</ref> 150,000 deaths from [[kidney failure]]<ref name=":7" />

200,000 indirect deaths from "causes related to" Schistosomiasis<ref name="The2013" />
|In tropical and subtropical regions<ref name=":2" /><ref name=":3" /><ref name=":4" /><ref name=":5" /><ref name=":6" />
|-
| ''[[Schistosoma haematobium]]''
|
| 112 (in Sub-Saharan Africa alone)<ref name=":7">Luke F. Pennington and Michael H. Hsieh (2014) [http://ebooks.benthamscience.com/book/9781608051489/ Immune Response to Parasitic Infections] {{Webarchive|url=https://web.archive.org/web/20141207140442/http://ebooks.benthamscience.com/book/9781608051489/ |date=2014-12-07 }}, Bentham e books, Vol 2, pp. 93–124, {{ISBN|978-1-60805-148-9}}</ref>
|
|-
| ''[[Echinococcus granulosus]]''
|
| 3<ref>Elisabetta Profumo, Alessandra Ludovisi, Brigitta Buttari, Maria, Angeles Gomez Morales and Rachele Riganò (2014) [http://ebooks.benthamscience.com/book/9781608051489/ Immune Response to Parasitic Infections] {{Webarchive|url=https://web.archive.org/web/20141207140442/http://ebooks.benthamscience.com/book/9781608051489/ |date=2014-12-07 }}, Bentham e books, Bentham Science Publishers, Vol 2, pp. 69–91, {{ISBN|978-1-60805-148-9}}</ref>
|
| Developing countries
|-
| colspan="5" | Not transmitted via soil and not classified as neglected tropical disease:
|-
| ''[[Toxocara canis]]''
| Dog [[roundworm]]
| 50
|
| Many regions of South-east Asia, Africa, and Central and South America<ref name="Jimenez2006" /><ref name=":1" /><ref name=":2" /><ref name=":3" /><ref name=":4" /><ref name=":5" />
|-
| ''[[Taenia solium]]''
| [[Pork tapeworm]]
| 50
|
| rowspan="4" | South America, Southeast Asia, West Africa and East Africa<ref name=":2" /><ref name=":3" /><ref name=":4" /><ref name=":5" />
|-
| ''[[Taenia saginata]]''
| [[Beef tapeworm]]
| 50
(all types of ''Taenia'': 40 to 60<ref name="eck">{{Cite book |title=Medical Microbiology |vauthors=Eckert J |publisher=Thieme |year=2005 |isbn=9781588902450 |veditors=Kayser FH, Bienz KA, Eckert J, Zinkernagel RM |location=Stuttgart |pages=560–562 |chapter=Helminths |chapter-url=https://books.google.com/books?id=L6OCIwb08LwC}}</ref>)
|
|-
| ''[[Hymenolepis nana]]''
| [[Dwarf tapeworm]]
| rowspan="2" |100
|
|-
| ''[[Hymenolepis diminuta]]''
| [[Rat tapeworm]]
|
|-
| ''[[Fasciola hepatica]]'',<br>''[[Fascioloides magna]]''
| [[Liver fluke]]
| rowspan="2" |50
|
| rowspan="2" |Largely in southern and eastern Asia but also in central and eastern Europe<ref name=":3" /><ref name=":4" />
|-
| ''[[Fasciolopsis buski]]''
| Giant [[intestinal fluke]]
|
|-
| ''[[Dracunculus medinensis]]''
| [[Guinea worm]]
| Negligible thanks to eradication program<ref name="WHO2014b">{{Cite web |date=February 2016 |title=Dracunculiasis (guinea-worm disease) Fact sheet N°359 (Revised) |url=https://www.who.int/mediacentre/factsheets/fs359/en |url-status=dead |archive-url=https://web.archive.org/web/20130730230030/http://www.who.int/mediacentre/factsheets/fs359/en/ |archive-date=July 30, 2013 |access-date=7 February 2016 |website=World Health Organization}}</ref>
|
| Formerly widespread in India, west Africa and southern Sudan<ref name=":3" /><ref name=":4" />
|-
| ''[[Trichostrongylus]] orientalis''
| [[Roundworm]]
| 1–3 ("several")
|
| Rural communities in Asia<ref name=":3" /><ref name=":4" />
|-
| Other
|
| 100
|
| Worldwide<ref name=":3" /><ref name=":4" />
|-
| colspan="2" |Total (number of infections)
| Approx. 3.5 billion
|
| Worldwide
|}

== See also ==
* [[Kato technique]]

== References ==
 {{Reflist}}

== External links ==
{{Medical resources
|  ICD10          = {{ICD10|B|83|9|b|65}}
|  ICD9           = {{ICD9|128.9}}
|  ICDO           =
|  OMIM           =
|  DiseasesDB     = 28826
|  MedlinePlus    =
|  eMedicineSubj  =
|  eMedicineTopic =
|  MeshID         = D006373
}}
* [https://www.who.int/topics/helminthiasis/en/ Information at WHO]
* [http://ec.europa.eu/research/health/infectious-diseases/neglected-diseases/helminth_en.html European Commission]
* [https://www.cdc.gov/parasites/sth/ Center for Disease Control and Prevention]
* [http://www.thiswormyworld.org/ Global Atlas of Helminth Infections] {{Webarchive|url=https://web.archive.org/web/20151108015800/http://www.thiswormyworld.org/ |date=2015-11-08 }}

{{Helminthiases}}
{{Diseases of Poverty}}
{{Vaccines}}
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{{Authority control}}

[[Category:Helminthiases]]
[[Category:Foodborne illnesses]]
[[Category:Ascaridomorpha]]
[[Category:Tropical diseases]]
[[Category:Conditions diagnosed by stool test]]
[[Category:Intestinal infectious diseases]]
[[Category:Abdominal pain]]
[[Category:Sanitation]]