The Pathophysiology, Ecology and Epidemiology of Haemonchus contortus Infection in Small Ruminants

Besier, R.B.; Kahn, Lewis; Sargison, Neil; Wyk, J.A. Van

doi:10.1016/bs.apar.2016.02.022

Cited by 215 publications

(158 citation statements)

References 159 publications

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“…Therefore, preserving the efficacy of IVM is becoming a serious issue now. H. contortus has a successful track record in anthelmintic resistance, and it has shown multidrug resistance including IVM [8,19]. The improper management and use of sublethal doses of drugs led to the rapid selection and adaptation of parasites against the drug.…”

Section: Introductionmentioning

confidence: 99%

A Whole Genome Re-Sequencing Based GWA Analysis Reveals Candidate Genes Associated with Ivermectin Resistance in Haemonchus contortus

Khan

Nisar

Yuan

et al. 2020

Genes

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The most important and broad-spectrum drug used to control the parasitic worms to date is ivermectin (IVM). Resistance against IVM has emerged in parasites, and preserving its efficacy is now becoming a serious issue. The parasitic nematode Haemonchus contortus (Rudolphi, 1803) is economically an important parasite of small ruminants across the globe, which has a successful track record in IVM resistance. There are growing evidences regarding the multigenic nature of IVM resistance, and although some genes have been proposed as candidates of IVM resistance using lower magnification of genome, the genetic basis of IVM resistance still remains poorly resolved. Using the full magnification of genome, we herein applied a population genomics approach to characterize genome-wide signatures of selection among pooled worms from two susceptible and six ivermectin-resistant isolates of H. contortus, and revealed candidate genes under selection in relation to IVM resistance. These candidates also included a previously known IVM-resistance-associated candidate gene HCON_00148840, glc-3. Finally, an RNA-interference-based functional validation assay revealed the HCON_00143950 as IVM-tolerance-associated gene in H. contortus. The possible role of this gene in IVM resistance could be detoxification of xenobiotic in phase I of xenobiotic metabolism. The results of this study further enhance our understanding on the IVM resistance and continue to provide further evidence in favor of multigenic nature of IVM resistance.

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Section: Introductionmentioning

confidence: 99%

A Whole Genome Re-Sequencing Based GWA Analysis Reveals Candidate Genes Associated with Ivermectin Resistance in Haemonchus contortus

Khan

Nisar

Yuan

et al. 2020

Genes

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“…This nematode causes weight loss, decreases milk production, and reduces fertility, and may lead to death in cases of high infection (BESIER et al, 2016). The control of these nematodes is traditionally performed with the administration of anthelmintics, but the inappropriate use of these drugs has favored the selection of resistant and multiresistant populations in some parts of the world (JACKSON et al, 2012;SANTOS et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Anthelmintic effect of thymol and thymol acetate on sheep gastrointestinal nematodes and their toxicity in mice

André

Cavalcante

Ribeiro

et al. 2017

Rev. Bras. Parasitol. Vet.

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Thymol is a monoterpene and acetylation form of this compound can reduce the toxicity and enhance its biological effects. The objective of this study was to evaluate the effect of thymol and thymol acetate (TA) on egg, larva and adult Haemonchus contortus and the cuticular changes, acute toxicity in mice and the efficacy on sheep gastrointestinal nematodes. In vitro tests results were analyzed by analysis of variance (ANOVA) and followed by comparison with Tukey test or Bonferroni. The efficacy of in vivo test was calculated by the BootStreet program. In the egg hatch test (EHT), thymol (0.5 mg/mL) and TA (4 mg/mL) inhibited larval hatching by 98% and 67.1%, respectively. Thymol and TA (8 mg/mL) inhibited 100% of larval development. Thymol and TA (800 µg/mL) reduced the motility of adult worms, by 100% and 83.4%, respectively. Thymol caused cuticular changes in adult worm teguments. In the acute toxicity test, the LD 50 of thymol and TA were 1,350.9 mg/kg and 4,144.4 mg/kg, respectively. Thymol and TA reduced sheep egg count per gram of faeces (epg) by 59.8% and 76.2%, respectively. In in vitro tests thymol presented better anthelmintic activity than TA. However TA was less toxic and in in vivo test efficacy was similar.Keywords: Acetylation, thymol, Haemonchus contortus, nematodes, sheep. ResumoTimol é um monoterpeno e a acetilação deste composto pode reduzir a toxicidade e potencializar os seus efeitos biológicos. O objetivo deste trabalho foi avaliar o efeito do timol e acetato de timolila (AT) sobre ovos, larvas e adultos de Haemonchus contortus e suas alterações cuticulares, toxicidade aguda em camundongos e a eficácia sobre nematoides gastrintestinais de ovinos. Os resultados dos testes in vitro foram analisados por análise de variância (ANOVA) e comparados pelo testes de Tukey ou Bonferroni. A eficácia do teste de redução da contagem de ovos nas fezes (RCOF) foi calculada pelo programa BootStreet. No teste de inibição da eclosão de ovos (TEO), timol (0,5 mg/mL) e AT (4 mg/mL) inibiram a eclosão das larvas em 98% e 67,1%, respectivamente. Timol e AT (8 mg/mL) inibiram 100% do desenvolvimento larval. Timol e AT (800 µg/mL) reduziram a motilidade dos nematoides adultos, em 100% e 83,4%, respectivamente. O timol provocou alterações cuticulares nos nematoides adultos. No teste de toxicidade aguda, a DL50 do timol e AT foi de 1.350,9 mg/kg e 4.144,4 mg/kg, respectivamente. Timol e AT reduziram a contagem de ovos por gramas de fezes (OPG) dos ovinos em 59,8% e 76,2%, respectivamente. Nos testes in vitro timol apresentou atividade melhor anti-helmíntica do que AT. Entretanto, AT foi menos tóxico do que o timol e no teste in vivo apresentaram eficácia semelhante.

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“…It might happen that imported Garole sheep could not tolerate the H. contortus infection with their poor nutritional status, whereas, local sheep protected the infection because of their acquired immunity. No age groups of animals are particularly prone to haemonchosis, however, lamb that has not received any natural acquired immunity is found to be more susceptible (Besier et al, 2016b). In this sheep farm, all mortality was found in lamb at the ages 6-7months of age; it might happen that all the Garole lamb were imported from different location that had not optimum natural acquired immunity against H. contortus resulting mortality.…”

Section: Discussionmentioning

confidence: 82%

Fatal haemonchosis (H. contortus) in Garole sheep at coastal region in Bangladesh

Paul¹,

Rahman²,

Haider³

et al. 2020

Res. Agric. Livest. Fish.

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Among gastro intestinal nematodes, Haemonchus contortus is one of the most pathogenic parasites of small ruminant in many countries of the world, including Bangladesh. Garole breed of sheep are adapted to the hot coastal regions in Bangladesh, and able to graze on marshy land. Sheep farm of Grameen Jano Unnayan Sangstha (GJUS), Bhola, a coastal region of Bangladesh faced sudden lamb mortality during the period of May, 2019 to August, 2019. Routine investigation was performed and data were summarized to find out the etiology, control measures and possible risk factors. During investigation both clinical and management history, physical examination and necropsy were performed. Salient case history includes: only Garole lamb with poor body condition at hot and humid climate died. Important clinical manifestation is defecation of bad odoured scanty blackish faeces. Physical examination of affected sheep revealed anemia and submandibular edema. Necropsy findings showed numerous Haemonchus sp. and frank haemorrhage in the abomasum. For control, all affected sheep were treated with anthelmintic, Nitroxynil (Nitronex®) and other supportive therapy; 4 hour after injection with Nitronex® one sick lamb was died, that might be due to anthelmintic stress, and others recovered within 3-5 days. This is the first report on haemonchosis in Garole sheep at coastal regions of Bangladesh; it will help the sheep rearers in the region to take protective measures against the fatal haemonchosis. Res. Agric., Livest. Fish.7(1): 107-112, April 2020

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The Pathophysiology, Ecology and Epidemiology of Haemonchus contortus Infection in Small Ruminants

Cited by 215 publications

References 159 publications

A Whole Genome Re-Sequencing Based GWA Analysis Reveals Candidate Genes Associated with Ivermectin Resistance in Haemonchus contortus

A Whole Genome Re-Sequencing Based GWA Analysis Reveals Candidate Genes Associated with Ivermectin Resistance in Haemonchus contortus

Anthelmintic effect of thymol and thymol acetate on sheep gastrointestinal nematodes and their toxicity in mice

Fatal haemonchosis (H. contortus) in Garole sheep at coastal region in Bangladesh

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