Use of arithmetic and geometric means in the calculation of anthelmintic efficacy

McKenna, P.B.

doi:10.1136/vr.141.18.472

Cited by 16 publications

(5 citation statements)

References 11 publications

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“…There is debate as to whether the percentage reduction in geometric or arithmetic mean FEC provides the more appropriate measure of efficacy in the FECRT (Dash et al 1988; McKenna 1997a; Smothers et al 1999; Dobson et al 2009). In the trials reported here, percentage reductions based on arithmetic means were less than those based on geometric means (except when 100%), consistent with the view that the use of arithmetic means may provide a more stringent test of anthelmintic efficacy (Vercruysse et al 2001).…”

Section: Discussionmentioning

confidence: 99%

Field efficacy and safety of an oral formulation of the novel combination anthelmintic, derquantel-abamectin, in sheep in New Zealand

Little¹,

Hodge²,

Watson³

et al. 2010

New Zealand Veterinary Journal

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AIM: To evaluate the efficacy and safety of the novel anthelmintic combination, derquantel-abamectin, against gastrointestinal nematode populations in sheep, under field-use conditions.METHODS: Controlled faecal egg count reduction tests (FECRT) were conducted in New Zealand in 14 trials, covering a range of geographic locations, farming enterprises, breeds, nematode populations, and anthelmintic-resistance profiles. Enrolled animals were naturally infected with mixed populations of gastrointestinal nematodes. All trials included a group treated with derquantel-abamectin, and a negative control group. Nine trials included additional groups each treated with a single- or dual-active oral reference anthelmintic, selected from albendazole, levamisole, albendazole-levamisole, ivermectin, abamectin and moxidectin. A total of 838 animals were enrolled across all trials, and were randomly allocated to treatment groups within blocks defined by faecal nematode egg counts (FEC) pre-treatment. On Day 0 derquantel-abamectin was administered orally at 1 ml/5 kg bodyweight (2 mg/kg derquantel, 0.2 mg/ kg abamectin), and each reference anthelmintic was given at the recommended label dose. Faecal samples were collected on Day 14 (± 1 day), to determine the percentage reduction in mean FEC for each anthelmintic tested. Larval differentiation was also performed post-treatment, to estimate efficacy at the genus level. Animals were weighed on or before Day 0, and on Day 14 (± 1 day) in 13 trials.RESULTS: The efficacy of derquantel-abamectin against mixed strongyle populations was ≥99.2%, based on the percentage reduction in geometric mean FEC. Nematodirus sp. was present in six trials at a level sufficient for efficacy calculations to be conducted; in all cases, the efficacy of derquantel-abamectin was 100%. In those trials where the efficacy of at least one reference anthelmintic was <95% against strongyles and/or Nematodirus sp., derquantel-abamectin was 100% effective. In five trials, the mean gain in bodyweight was significantly greater in the derquantel-abamectin group than the negative controls.CONCLUSIONS AND CLINICAL RELEVANCE: When administered orally at 1 ml/5 kg bodyweight, derquantel-abamectin is highly effective for the treatment of gastrointestinal nematodes in sheep, including populations of strongyles and Nematodirus sp. with resistance to one or more single- or dual-active anthelmintics. Derquantel-abamectin presents sheep producers with a unique opportunity to introduce a new class of anthelmintic to their nematode control programmes, with the added benefits offered by a combination anthelmintic.

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Section: Discussionmentioning

confidence: 99%

Field efficacy and safety of an oral formulation of the novel combination anthelmintic, derquantel-abamectin, in sheep in New Zealand

Little¹,

Hodge²,

Watson³

et al. 2010

New Zealand Veterinary Journal

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“…As shown by the Senegalese experiences with PZQ, however, more sophisticated analysis is essential before definite and far-reaching conclusions can be drawn. In veterinary science, arithmetic mean egg counts are preferred over geometric mean counts because they are more sensitive and allow an earlier detection of resistance (102). This may be justified in situations where AR is known to exist and needs only to be confirmed in a particular situation.…”

Section: Detection Of Drug Resistancementioning

confidence: 99%

Drug Resistance in Human Helminths: Current Situation and Lessons from Livestock

Geerts

Gryseels

2000

Clinical Microbiology Reviews

231

130

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“…The arithmetic mean was used in the estimation of anthelmintic efficacy as was suggested by McKenna (1997).…”

Section: Parasitological Techniquesmentioning

confidence: 99%

Comparative pharmacokinetic and pharmacodynamic response of single and double intraruminal doses of ivermectin and moxidectin in nematode-infected lambs

Lloberas¹,

Álvarez

Entrocasso³

et al. 2015

New Zealand Veterinary Journal

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Use of arithmetic and geometric means in the calculation of anthelmintic efficacy

Cited by 16 publications

References 11 publications

Field efficacy and safety of an oral formulation of the novel combination anthelmintic, derquantel-abamectin, in sheep in New Zealand

Field efficacy and safety of an oral formulation of the novel combination anthelmintic, derquantel-abamectin, in sheep in New Zealand

Drug Resistance in Human Helminths: Current Situation and Lessons from Livestock

Comparative pharmacokinetic and pharmacodynamic response of single and double intraruminal doses of ivermectin and moxidectin in nematode-infected lambs

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