Benzimidazole resistance in <i>Nematodirus battus</i>

Mitchell, Siân; Mearns, Rebecca; Richards, Iain; Donnan, Alison; Bartley, David J.

doi:10.1136/vr.d3584

Cited by 19 publications

(23 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For LEV and ML, four and three tests respectively indicated treatment failure. There have been only a few reports of anthelmintic resistance among Nematodirus species in Ireland or Britain [19,20] and our study is in agreement with these findings. The reason for Nematodirus treatment failure is unknown but it may represent true anthelmintic resistance, although further work would be required to determine this.…”

Section: Resultssupporting

confidence: 93%

High level of treatment failure with commonly used anthelmintics on Irish sheep farms

Keane

Keegan

Good³

et al. 2014

Ir Vet J

View full text Add to dashboard Cite

BackgroundIn 2013 a Technology Adoption Program for sheep farmers was established to encourage the implementation of best management practices on sheep farms in Ireland. There were 4,500 participants in this programme in 2013. As part of this programme, farmers had the option to carry out a drench test to establish the efficacy of their anthelmintic treatment.ResultsFlock faecal samples were collected before and after treatment administration and gastrointestinal nematode eggs enumerated. In total there were 1,893 participants in the task, however only 1,585 included both a pre- and post-treatment faecal sample. Of those, 1,308 provided information on the anthelmintic product that they used with 46%, 23% and 28% using a benzimidazole (BZ), levamisole (LEV) and macrocyclic lactone (ML) product respectively. The remaining farmers used a product inapplicable for inclusion in the task such as a flukicide or BZ/LEV combination product. Samples were included for analysis of drench efficacy if the pre-treatment flock egg count was ≥200 eggs per gram and the interval post-sampling was 10–14 days for BZ products, 4–7 days for LEV products and 14–18 days for ML products. These criteria reduced the number of valid tests to 369, 19.5% of all tests conducted. If the reduction post-treatment was ≥95% the treatment was considered effective. Only 51% of treatments were considered effective using this criterion. There was a significant difference in efficacy between the anthelmintic drug classes with BZ effective in only 30% of treatments, LEV effective in 52% of cases and ML effective in 76% of cases.ConclusionsGastrointestinal nematode anthelmintic treatments, as practiced on Irish farms, have a high failure rate. There was a significant difference between the efficacies of the anthelmintic classes with BZ the least effective and ML the most effective.

show abstract

Section: Resultssupporting

confidence: 93%

High level of treatment failure with commonly used anthelmintics on Irish sheep farms

Keane

Keegan

Good³

et al. 2014

Ir Vet J

View full text Add to dashboard Cite

show abstract

“…The results here provide confirmation, based on residual worm burden and faecal egg count analysis post benzimidazole treatment, of the preliminary results of the first reported case of BZ resistance in N. battus globally [27]. The zero percentage efficacy noted here, poses the question as to whether any members of the benzimidazole class of anthelmintics would be effective against Estimated total worm burden Figure 2 Individual estimated total worm burden of the two groups of lambs infected with 6000 Nematodirus battus infective larvae.…”

Section: Discussionsupporting

confidence: 74%

Phenotypic and genotypic analysis of benzimidazole resistance in the ovine parasite Nematodirus battus

Morrison

Mitchell

Mearns

et al. 2014

Vet Res

Self Cite

View full text Add to dashboard Cite

Benzimidazole resistance is common amongst many ovine trichostrongylid nematodes species globally. Although anthelmintics have been used for over half a century in some areas of the world for the control of Nematodirus battus, resistance has never been detected. Veterinary investigations conducted in 2010 demonstrated reduced efficacy in a flock that had been treated previously with fenbendazole (FBZ), suggesting probable resistance in N. battus. Infective larvae (L3; designated MNba2) were generated from the original material to conduct a controlled efficacy test (CET). Faecal egg counts showed an average of 37% reduction in the FBZ treated group 7 days post treatment compared to the untreated lambs. Average worm burden results showed no reduction after FBZ treatment compared to the untreated group (3850 and 3850 worms respectively). A molecular assay to assess the frequency of the commonly associated single nucleotide polymorphisms (SNP) in the β-tubulin isotype 1 gene, F200Y and E198A, was developed. Larval genotypes were predominantly homozygous resistant at codon 200 SNP, ranging from 56%-83% and remained stable at 70% for adult worm populations taken from treated and control lambs in the CET. Only susceptible genotypes were found at codon 198. The allele frequency for F200Y ranged between 80-83% in adult worms taken from the CET from treated and control lambs. The results confirmed initial findings and demonstrated the first report of FBZ resistance in N. battus whilst providing evidence that the P200 point mutation in the β-tubulin isotype 1 gene is a potential mechanism of resistance in the species.

show abstract

“…The F200Y BZ-R haplotype was found to be present in an F1 hybrid worm, opening up the potential for introgression of BZ-R alleles from H. contortus into H. placei . Finally, the first case of BZ-R has recently been reported in Nematodirus battus in the UK ( Mitchell et al, 2011 ). This parasite is responsible for severe outbreaks of disease in lambs in spring and has always been considered to be naturally susceptible to BZ anthelmintics.…”

Section: Benzimidazole Resistance: Taking Snp-based Tests To the Fielmentioning

confidence: 99%

Recent advances in candidate-gene and whole-genome approaches to the discovery of anthelmintic resistance markers and the description of drug/receptor interactions

Kotze¹,

Hunt²,

Skuce³

et al. 2014

International Journal for Parasitology: Drugs and Drug Resistan

170

180

View full text Add to dashboard Cite

show abstract

Benzimidazole resistance in Nematodirus battus

Abstract: oTHers (1995) World Association for the Advancement of Veterinary Parasitology (WAAVP) second edition of guidelines for evaluating the efficacy of anthelmintics in ruminants (bovine, ovine, caprine).

Cited by 19 publications

References 2 publications

High level of treatment failure with commonly used anthelmintics on Irish sheep farms

High level of treatment failure with commonly used anthelmintics on Irish sheep farms

Phenotypic and genotypic analysis of benzimidazole resistance in the ovine parasite Nematodirus battus

Recent advances in candidate-gene and whole-genome approaches to the discovery of anthelmintic resistance markers and the description of drug/receptor interactions

Contact Info

Product

Resources

About