Haemonchosis: dealing with the increasing threat of the barber's pole worm

Abstract

Haemonchus contortus is a trichostrongyle nematode parasite of sheep and goats, and worldwide is considered to be the most important parasite of these species. It has a similar lifecycle to other parasitic trichostrongyle gastrointestinal nematodes, but it has a markedly higher fecundity, a preference for higher temperatures and a short pasture development time, which makes it epidemiologically different. Similarly, because of its blood-feeding habit the disease produced is distinct from parasitic gastroenteritis. This article summarises the differences in biology and control of H. contortus to other gastrointestinal nematodes of sheep, and covers specific control measures such as the use of FAMACHA© scoring, use of closantel and nitroxynil, the H. contortus vaccine, the effect of copper oxide wire particles, and the potential for breeding haemonchosis-resistant sheep and other future developments in H. contortus control.

Guide to advances in the control of gastrointestinal roundworms in sheep

“…In this way, targeted selective treatment on the basis of pallor can be used for haemonchosis control (Fig 2). With haemonchosis becoming an increasingly common problem in the UK, especially in the south, some authors are now advocating the routine use of FAMACHA scoring in flocks where haemonchosis has been diagnosed (Crilly and others 2020). As Haemonchus contortus can be treated by narrow‐spectrum products (eg, closantel) which are effective against it but that do not affect other GIN species, determining that haemonchosis is the major problem (eg, by use of peanut agglutinin staining [see below]) rather than parasitic gastroenteritis allows use of these products, in turn reducing selection pressure in other GIN species for resistance to broad‐spectrum anthelmintics.…”