The role of arithmetic and geometric mean worm egg counts in faecal egg count reduction tests and in monitoring strategic drenching programs in sheep

Dash, K.M.; Hall, E.; Barger, I.A.

doi:10.1111/j.1751-0813.1988.tb07359.x

Cited by 136 publications

(83 citation statements)

References 7 publications

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“…In the current study, FECR% was determined by three different methods of calculations used previously by other researchers (Dash et al 1988;Coles et al 1992;Craven et al 1998;Pook et al 2002;Milillo et al 2009). Calculation of FECR% by method 2 in field trials was deemed more suitable as it requires no control group and generally has lower variances (Pook et al 2002).…”

Section: Discussionmentioning

confidence: 99%

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A field study on the anthelmintic resistance of Parascaris spp. in Arab foals in the Riyadh region, Saudi Arabia

Alanazi

Mukbel

Alyousif

et al. 2017

Veterinary Quarterly

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Background: In the last decade, Parascaris spp. resistance to anthelmintics has been recorded in many countries. In Saudi Arabia, there are limited data available on Parascaris spp. resistance to anthelmintics. Objective: To determine the current status of ivermectin, abamectin and praziquantel combined, and fenbendazole resistance to Parascaris spp. in horses in Saudi Arabia. Methods: Three hundred and forty-one foals from eleven different farms were examined by faecal egg count (FEC). The foals were all Arab horses aged 17.2 § 4.5 (SD) months. Ivermectin (n = 46 foals), abamectin and praziquantel combined (n = 46), and fenbendazole (n = 46) were administered on day 0 and faeces were collected on day 14. The study comprised 41 untreated foals as controls. Animals that have FEC of 100 eggs per gram (EPG) were used to measure anthelmintic efficacy. Parascaris spp. populations were considered susceptible when faecal egg count reduction (FECR) was 95% associated with a lower 95% confidence limit (LCL) >90%, suspected resistant when FECR 90% or LCL <90% and resistant when FECR <90% and LCL <90%. Results: Prevalence of Parascaris spp. infection was 53% (179/341 horses). Anthelmintic resistance to Parascaris spp. were highest following fenbendazole (55% of farms and 65% of foals) and to a lower extent following ivermectin or the combination of abamectin and praziquantel which comprised 27% of farms (and 46% of foals) and 18% of farms (and 10% of foals), respectively. Conclusion: These data indicate that anthelmintics-resistant Parascaris spp. populations are present on horse farms in Saudi Arabia.

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Section: Discussionmentioning

confidence: 99%

“…Reductions-based AM values (but no CL) were calculated by the method of Dash et al (1988). Calculation of GM values was as follows: GM = exp [ P 1 log e(X 1 + 1)/n] ¡ 1 (where n counts X 1 ,...,X n and exp = exponential function).…”

Section: Calculations and Analysismentioning

confidence: 99%

A field study on the anthelmintic resistance of Parascaris spp. in Arab foals in the Riyadh region, Saudi Arabia

Alanazi

Mukbel

Alyousif

et al. 2017

Veterinary Quarterly

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“…where T1 and T2 were pre-and posttreatment arithmetic means of the GIN epg in treated groups, respectively, and C1 and C2 were pre-and posttreatment arithmetic means of the epg in the controls (i.e., untreated animals), respectively (Dash et al 1988).…”

Section: Fecal Egg Count Reduction Calculationsmentioning

confidence: 99%

“…Meanwhile, other authors have described geometric means as more appropriate estimators of the central tendency parameter for parasite populations which are usually overdispersed and, therefore, do not have a constant variance (Smothers et al 1999). While some FECR formulae take into account both pre-and posttreatment FECs in both treated and control animals (Presidente 1985;Dash et al 1988), other variations of the FECR calculation only take into consideration the pre-and posttreatment FECs of treated animals (McKenna 2006), or the posttreatment FECs of both treated and untreated animals (Coles et al 2006), thereby reducing the number of fecal samples required. Lastly, Mejia et al (2003) described an alternate approach for calculating the FECR, using a general linear mixed model (GLMM) to provide FEC means corrected for other covariable effects, such as animal weight and treatment.…”

Section: Introductionmentioning

confidence: 99%

Erratum to: Comparison of calculation methods used for the determination of anthelmintic resistance in sheep in a temperate continental climate

et al. 2015

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This study compared results obtained with five different fecal egg count reduction (FECR) calculation methods for defining resistance to ivermectin, fenbendazole, and levamisole in gastrointestinal nematodes of sheep in a temperate continental climate: FECR 1 and FECR 2 used preand posttreatment fecal egg count (FEC) means from both treated and control animals, but FECR 1 used arithmetic means, whereas FECR 2 used geometric means; FECR 3 used arithmetic means for pre-and posttreatment FECs from treated animals only; FECR 4 was calculated using only arithmetic means for posttreatment FECs from treated and control animals; and FECR 5 was calculated using mean FEC estimates from a general linear mixed model. The classification of farm anthelmintic resistance (AR) status varied, depending on which FECR calculation method was used and whether a bias correction term (BCT, i.e., half the minimum detection limit) was added to the zeroes or not. Overall, agreement between all methods was higher when a BCT was used, particularly when levels of resistance were low. FECR 4 showed the highest agreement with all the other FECR methods. We therefore recommend that small ruminant clinicians use the FECR 4 formula with a BCT for AR determination, as this would reduce the cost of the FECRT, while still minimizing bias and allowing for comparisons between different farms. For researchers, we recommend the use of FECR 1 or FECR 2 , as the inclusion of both pre-and posttreatment FECs and use of randomly allocated animals in treatment and control groups makes these methods mathematically more likely to estimate the true anthelmintic efficacy.

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“…The anthelmintic efficacy of the each extract residues was calculated using the following formula given by Dash et al, (1988) EPG before treatment-EPG after treatment % efficacy = _____________________ x 100 EPG before treatment…”

Section: Determination Of Anthelmintic Efficacymentioning

confidence: 99%

Evaluation of Anthelmintic Efficacy of Nicotiana tabacum against Gastrointestinal Nematodes of Goats

Sastya¹,

Kumar²,

Vatsya³

2017

Int.J.Curr.Microbiol.App.Sci

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The role of arithmetic and geometric mean worm egg counts in faecal egg count reduction tests and in monitoring strategic drenching programs in sheep

Cited by 136 publications

References 7 publications

A field study on the anthelmintic resistance of Parascaris spp. in Arab foals in the Riyadh region, Saudi Arabia

A field study on the anthelmintic resistance of Parascaris spp. in Arab foals in the Riyadh region, Saudi Arabia

Erratum to: Comparison of calculation methods used for the determination of anthelmintic resistance in sheep in a temperate continental climate

Evaluation of Anthelmintic Efficacy of Nicotiana tabacum against Gastrointestinal Nematodes of Goats

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