Modelling anthelmintic resistance by extending eggCounts package to allow individual efficacy

Wang, Craig; Torgerson, Paul R.; Kaplan, Ray M.; George, Melissa M.; Furrer, Reinhard

doi:10.1016/j.ijpddr.2018.07.003

Cited by 56 publications

(36 citation statements)

References 24 publications

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“…The statistical analysis was limited to horses with an excretion level of ≥ 150 eggs per gram faeces (EPG) and stud farms with at least 6 horses shedding eggs above this threshold. FECRT 95% confidence intervals were estimated by 1000 bootstraps using the fecrtCI() function as implemented in the eggCounts package v2.1-2 [12]. To account for sex-and age-specific variation in Parascaris spp.…”

Section: Resultsmentioning

confidence: 99%

A survey of ivermectin resistance in Parascaris species infected foals in south-eastern Poland

et al. 2020

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Parascaris spp. are major gastro-intestinal nematodes that infect foals and can lead to respiratory symptoms, poor growth, and in some cases obstruction of the small intestine and death. Ivermectin resistance has been reported for Parascaris spp. in many countries. In Poland, the knowledge of the level of resistance against ivermectin in Parascaris spp. is limited. The aim of this study was to examine the efficacy of ivermectin against Parascaris spp. in foals from southeastern Poland. Foals (n = 225 = reared in 7 stud farms) were treated orally with ivermectin paste. Faecal samples were collected from the rectum of each foal or from the environment straight after defaecation on 1 day prior and 2 weeks after deworming. A faecal egg count (FEC) was performed using the McMaster method with a minimum detection limit of 50 eggs/g. FEC reduction (FECR) was calculated using the Faecal Egg Count Reduction Test. The statistical analysis was limited to foals excreting more than 150 eggs/g before treatment and to stud farms with at least 6 foals excreting at or above this level. Confidence intervals were determined by 1000 bootstraps at farm level and the contribution of sex and age to FECR was quantified using a generalized equation estimation procedure. Parascaris spp. eggs were found in 40% of the foals. Following ivermectin treatment, Parascaris spp. eggs were identified in 28.4% of the foals. The mean estimated FECR ranged from 44% to 97% and average efficacy was 49.3%. FECR was more pronounced in older foals (P-values = 0. 003). The FECR was more pronounced in males than in females (P value = 0.028). This study is the first to indicate a reduced efficacy of ivermectin against Parascaris spp. in foals in Poland.

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Section: Resultsmentioning

confidence: 99%

A survey of ivermectin resistance in Parascaris species infected foals in south-eastern Poland

et al. 2020

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“…Spearman correlation coefficients were calculated to estimate the correlations between EPG and test day milk yield and of the FAMACHA score with PCV and EPG. FECRTs and corresponding 95 % credible intervals (CI) were determined using the function fecr_stan from the R-package eggCounts 2.3 ( Wang et al, 2018 ). For calculations, a paired design model with individual efficacy was used.…”

Section: Methodsmentioning

confidence: 99%

“…For calculations, a paired design model with individual efficacy was used. As recommended by Wang et al (2018) the 2.5 % and 97.5 % percentiles as the 95 % CI and the median as the summary statistics were used. Observations with zero EPG pre-treatment were excluded prior to the analysis.…”

Section: Methodsmentioning

confidence: 99%

Potentials of using milk performance data and FAMACHA score as indicators for Targeted Selective Treatment in Lacaune dairy sheep in Switzerland

Schwarz

Bapst²,

Holinger

et al. 2020

Veterinary Parasitology

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“…Groups with a mean pre-treatment FEC < 40 epg were also excluded from further analysis due to the low FEC. Data were analysed using the Shiny web interface for the R package eggCounts with paired samples and allowing individual efficacy [23]. If the mean FEC increased after anthelmintic treatment, the default prior for modelling the reduction was changed to Uniform(0,4) [23].…”

Section: Faecal Egg Count Reduction Testmentioning

confidence: 99%

“…Data were analysed using the Shiny web interface for the R package eggCounts with paired samples and allowing individual efficacy [23]. If the mean FEC increased after anthelmintic treatment, the default prior for modelling the reduction was changed to Uniform(0,4) [23]. Resistance was considered present if the percentage reduction in egg count was < 95% and the lower value of the 95% uncertainty interval was < 90%.…”

Section: Faecal Egg Count Reduction Testmentioning

confidence: 99%

Anthelmintic resistance among gastrointestinal nematodes of cattle on dairy calf to beef farms in Ireland

et al. 2020

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Background: The control of gastrointestinal nematodes (GIN) of cattle in pasture-based production systems such as Ireland is highly dependent on the availability of efficacious anthelmintics. There is very little information available on the efficacy of the broad-spectrum anthelmintics against GIN of cattle in Ireland and the aim of this study was to determine the prevalence of anthelmintic resistance on dairy calf to beef farms. Results: GIN burden was monitored on thirty-six recruited farms by performing herd level faecal egg counts (FEC) every 2 weeks. Of these, nine farms were lost from the study as calves were treated with an anthelmintic for Dictyocaulus viviparus, two were lost as they treated for GIN, one dropped out of the study and on one the herd FEC did not reach the threshold for carrying out the Faecal Egg Count Reduction Test (FECRT). On the remaining 23 farms, once the herd FEC reached 100 eggs per gram, a FECRT was carried out. Pre and post-treatment larval cultures were also performed to identify the GIN to genus level. The efficacy of fenbendazole, levamisole, ivermectin and moxidectin was evaluated on 15, 11, 16 and 11 farms respectively. Resistance to fenbendazole was identified on 9 farms (60%) with resistance suspected on a further farm. Resistance to levamisole, ivermectin and moxidectin was detected on 2 (18%), 16 (100%) and 8 (73%) farms respectively. The predominant genera detected pre and post-treatment were Cooperia and Ostertagia with both genera detected post-treatment with fenbendazole and ivermectin. Due to the low proportion of Ostertagia spp. pre-treatment, the efficacy of levamisole or moxidectin against this genus could not be reliably established. Conclusions: Anthelmintic resistance was widespread on the sampled dairy calf to beef farms in Ireland with resistance to benzimidazole, levamisole, ivermectin and moxidectin detected.

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Modelling anthelmintic resistance by extending eggCounts package to allow individual efficacy

Cited by 56 publications

References 24 publications

A survey of ivermectin resistance in Parascaris species infected foals in south-eastern Poland

A survey of ivermectin resistance in Parascaris species infected foals in south-eastern Poland

Potentials of using milk performance data and FAMACHA score as indicators for Targeted Selective Treatment in Lacaune dairy sheep in Switzerland

Anthelmintic resistance among gastrointestinal nematodes of cattle on dairy calf to beef farms in Ireland

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