The use of a simplified faecal egg count reduction test for assessing anthelmintic efficacy on Belgian and German cattle farms

El-Abdellati, Abdelkarim; Charlier, Johannes; Geldhof, Peter; Levecke, Bruno; Demeler, Janina; Samson‐Himmelstjerna, Georg von; Claerebout, Edwin; Vercruysse, Jozef

doi:10.1016/j.vetpar.2010.01.015

Cited by 50 publications

(37 citation statements)

References 15 publications

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“…FLOTAC will require smaller sample sizes compared to McMaster method), but this will also be affected by the level and variation in egg excretion between subjects. In veterinary sciences, there is already empirical evidence that low FECs may confound interpretation of ERR results, particularly when sample sizes are small or diagnostic methods are not precise (El-Abdellati et al, 2010;Levecke et al, 2011b), and this is supported by evidence from statistical modelling (Vidyashankar et al, 2007). As a consequence, performing an ERR where all three STHs are being evaluated concurrently in the same population, requires a different study design, especially because of the differences in fecundity between the helminth species: A. lumbricoides >> hookworm > T. trichiura (Bethony et al, 2006).…”

Section: Sample Size and Variation In Egg Excretionmentioning

confidence: 99%

Is anthelmintic resistance a concern for the control of human soil-transmitted helminths?

Vercruysse

Albonico²,

Behnke

et al. 2011

International Journal for Parasitology: Drugs and Drug Resistan

232

220

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The major human soil-transmitted helminths (STH), Ascaris lumbricoides, hookworms (Necator americanus and Ancylostoma duodenale) and Trichuris trichiura have a marked impact on human health in many parts of the world. Current efforts to control these parasites rely predominantly on periodic mass administration of anthelmintic drugs to school age children and other at-risk groups. After many years of use of these same drugs for controlling roundworms in livestock, high levels of resistance have developed, threatening the sustainability of these livestock industries in some locations. Hence, the question arises as to whether this is likely to also occur in the human STH, thereby threatening our ability to control these parasites. This is particularly important because of the recent increase in mass control programmes, relying almost exclusively on benzimidazole anthelmintics. It will be important to ensure that resistance is detected as it emerges in order to allow the implementation of mitigation strategies, such as use of drug combinations, to ensure that the effectiveness of the few existing anthelmintic drugs is preserved. In this review we address these issues by firstly examining the efficacy of anthelmintics against the human STH, and assessing whether there are any indications to date that resistance has emerged. We then consider the factors that influence the effect of current drug-use patterns in selecting for resistant parasite populations. We describe the tools currently available for resistance monitoring (field-based coprological methods), and those under development (in vitro bioassays and molecular tests), and highlight confounding factors that need to be taken into account when interpreting such resistance-monitoring data. We then highlight means to ensure that the currently available tools are used correctly, particularly with regard to study design, and we set appropriate drug-efficacy thresholds. Finally, we make recommendations for monitoring drug efficacy in the field, as components of control programmes, in order to maximise the ability to detect drug resistance, and if it arises to change control strategy and prevent the spread of resistance.

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Section: Sample Size and Variation In Egg Excretionmentioning

confidence: 99%

Is anthelmintic resistance a concern for the control of human soil-transmitted helminths?

Vercruysse

Albonico²,

Behnke

et al. 2011

International Journal for Parasitology: Drugs and Drug Resistan

232

220

View full text Add to dashboard Cite

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“…The current recommendations to conduct and analyse FECRT in cattle derive from guidelines by the World Association for Advancement of Veterinary Parasitology (WAAVP), which were originally developed for detection of AR in sheep nematodes (Coles et al., 1992). However, potential limitations have been highlighted concerning the use of FECRT with bovine nematodes, mainly due to the lower faecal egg excretion of cattle, compared to sheep, and the highly aggregated distribution of FEC in cattle groups (Coles, 2002, Coles et al., 2006, Demeler et al., 2010, El-Abdellati et al., 2010, Sutherland and Leathwick, 2011). These factors may limit the correct analysis of FECRT data and inference of drug efficacy in cattle using the WAAVP guidelines.…”

Section: Introductionmentioning

confidence: 99%

Efficacy of ivermectin against gastrointestinal nematodes of cattle in Denmark evaluated by different methods for analysis of faecal egg count reduction

Pena-Espinoza

Thamsborg

Denwood

et al. 2016

International Journal for Parasitology: Drugs and Drug Resistan

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The efficacy of ivermectin (IVM) against gastrointestinal nematodes in Danish cattle was assessed by faecal egg count reduction test (FECRT). Six cattle farms with history of clinical parasitism and avermectin use were included. On the day of treatment (Day 0), 20 naturally infected calves per farm (total n = 120) were stratified by initial faecal egg counts (FEC) and randomly allocated to a treatment group dosed with 0.2 mg IVM kg−1 body weight s.c. (IVM; n = 10) or an untreated control group (CTL; n = 10). Individual FEC were obtained at Day 0 and Day 14 post-treatment and pooled faeces by group were cultured to isolate L3 for detection of Ostertagia ostertagi and Cooperia oncophora by qPCR. Treatment efficacies were analysed using the recommended WAAVP method and two open-source statistical procedures based on Bayesian modelling: ‘eggCounts’ and ‘Bayescount’. A simulation study evaluated the performance of the different procedures to correctly identify FEC reduction percentages of simulated bovine FEC data representing the observed real data. In the FECRT, reduced IVM efficacy was detected in three farms by all procedures using data from treated animals only, and in one farm according to the procedures including data from treated and untreated cattle. Post-treatment, O. ostertagi and C. oncophora L3 were detected by qPCR in faeces of treated animals from one and three herds with declared reduced IVM efficacy, respectively. Based on the simulation study, all methods showed a reduced performance when FEC aggregation increased post-treatment and suggested that a treatment group of 10 animals is insufficient for the FECRT in cattle. This is the first report of reduced anthelmintic efficacy in Danish cattle and warrants the implementation of larger surveys. Advantages and caveats regarding the use of Bayesian modelling and the relevance of including untreated cattle in the FECRT are discussed.

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“…Although they are simple and user friendly (Levecke et al 2009), their chief limitation is the high analytic sensitivity (ranging from 10 to 50) that may thwart interpretation of the obtained FECR (El-Abdellati et al 2010). This is particularly so in small herds, when the parasite population is highly aggregated or when animals are excreting a low number of eggs.…”

Section: Introductionmentioning

confidence: 99%

Monitoring drug efficacy against gastrointestinal nematodes when faecal egg counts are low: do the analytic sensitivity and the formula matter?

et al. 2011

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The faecal egg count reduction test (FECR) is the recommended technique to monitor anthelmintic drug efficacy in livestock. However, results are often inconclusive due to the low analytic sensitivity of the diagnostic technique or the conflict in results from FECR formulae. A novel experimental set-up was, therefore, used to compare the impact of analytic sensitivity and formulae on FECR results. Four McMaster techniques (analytic sensitivities 50, 33.3, 15 and 10) and a FLOTAC technique (analytic sensitivity ~ 1) were used on faecal samples of 30 calves with a FEC of less than 200 eggs per gram. True drug efficacies of 70%, 80% and 90% were experimentally mimicked by comparing FEC before and after dilution (3:10, 2:10 and 1:10, respectively). The FECR was summarized using group (FECR(1)) and individual (FECR(2)) based formulae. There was a significant increase in precision of FECR when the analytic sensitivity increased (p < 0.0001). The precision also depended on the formula used, FECR(1) (p < 0.05) resulting in more precise FECR compared to FECR(2). The accuracy of the FECR differed marginally between the two formulae (p = 0.06), FECR(1) being more accurate. In conclusion, the present study describes a novel methodology to compare techniques for the precision and the accuracy of their FECR results. The results underscored that techniques with high analytic sensitivity will improve the interpretation of FECR in animal populations where baseline FEC are low. They also point out that the precision of individual-based formulae is affected by the analytic sensitivity.

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The use of a simplified faecal egg count reduction test for assessing anthelmintic efficacy on Belgian and German cattle farms

Cited by 50 publications

References 15 publications

Is anthelmintic resistance a concern for the control of human soil-transmitted helminths?

Is anthelmintic resistance a concern for the control of human soil-transmitted helminths?

Efficacy of ivermectin against gastrointestinal nematodes of cattle in Denmark evaluated by different methods for analysis of faecal egg count reduction

Monitoring drug efficacy against gastrointestinal nematodes when faecal egg counts are low: do the analytic sensitivity and the formula matter?

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