Editing Haemonchus contortus (section)

{{Short description|Species of roundworm}}
{{Italic title}}
{{Speciesbox
| name = ''Haemonchus contortus''
|image= CSIRO ScienceImage 10819 The tail ends of 11 Haemonchus contortus barbers pole worm adult females The worms are all taken from one sheep infected with a single strain of this worm species.jpg
| image_caption = These 11 ''Haemonchus contortus'' adult females were taken from one sheep infected with a single strain of this worm species.
| image2 = Haemonchus contortus.jpg
| image2_caption = ''Haemonchus contortus'' egg
| taxon = Haemonchus contortus
| authority = (Rudolphi, 1803) Cobb, 1898
| synonyms = ''Haemonchus placei'' <small>Place, 1893</small><ref name="IRMNG">{{cite web |title=IRMNG - Haemonchus placei Place, 1893 |url=https://www.irmng.org/aphia.php?p=taxdetails&id=11473085 |website=www.irmng.org |access-date=21 October 2021}}</ref> (closely related species)
}}

'''''Haemonchus contortus''''', also known as the [[barber's pole]] worm, is a very common parasite and one of the most pathogenic [[nematode]]s of [[ruminant]]s. Adult worms attach to [[abomasum|abomasal]] mucosa and feed on the blood. This parasite is responsible for [[anemia]], [[oedema]], and death of infected [[sheep]] and [[goats]], mainly during summer in warm, humid climates.<ref>[http://attra.ncat.org/downloads/goat_barber_pole.pdf Burke, Joan, Research Animal Scientist. ''Management of Barber pole Worm in Sheep and Goats in the Southern U.S.'' USDA, ARS, Dale Bumpers Small Farms Research Center, Booneville, AR.] {{Webarchive|url=https://web.archive.org/web/20090305042910/http://attra.ncat.org/downloads/goat_barber_pole.pdf |date=2009-03-05 }}></ref>

Females may lay over 10,000 eggs a day,<ref>{{Cite web|title=Barber's pole worm (''Haemonchus contortus'') at Australian Wool Innovation Limited.|url=http://www.wool.com/Grow_WormBoss_Know-your-worms_Barbers-pole-worm.htm|url-status=dead|archive-url=https://web.archive.org/web/20120430210231/http://www.wool.com/Grow_WormBoss_Know-your-worms_Barbers-pole-worm.htm|archive-date=2012-04-30|access-date=2010-11-04}}</ref> which pass from the host animal in the [[faeces]]. After hatching from their eggs, ''H. contortus'' [[larva]]e [[ecdysis|molt]] several times, resulting in an L3 form that is [[infection|infectious]] for the animals. The host ingests these larvae when grazing. The L4 larvae, formed after another molt, and adult worms suck blood in the abomasum of the animal, potentially giving rise to anaemia and oedema, which eventually can lead to death.<ref>{{cite web | title = ''Haemonchus'', ''Ostertagia'', and ''Trichostrongylus'' spp | work = The Merck Veterinary Manual | year = 2006 | url = http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/22413.htm | access-date = 2007-07-01 }}</ref>

The infection, called haemonchosis, causes large economic losses for farmers around the world, especially for those living in warmer climates. [[Anthelminthics]] are used to prevent and treat these, and other, worm infections, but [[drug resistance|resistance]] of the [[parasitism|parasites]] against these [[chemical substance|chemicals]] is growing. Some breeds, such as the [[West African Dwarf goat]] and N'Dama cattle, are more resistant than other breeds to ''H. contortus'' (haemonchotolerance).<ref name="ChiejinaBehnke2015">{{cite journal |doi=10.1051/parasite/2015006 |pmid=25744655 |pmc=4321401 |title=Haemonchotolerance in West African Dwarf goats: Contribution to sustainable, anthelmintics-free helminth control in traditionally managed Nigerian dwarf goats |journal=Parasite |volume=22 |pages=7 |year=2015 |last1=Chiejina |first1=Samuel N |last2=Behnke |first2=Jerzy M |last3=Fakae |first3=Barineme B }}</ref>