Multigeneric resistance to monepantel on a UK sheep farm

Bartley, D. J., Hamer, K., Andrews, L., Sargison, N. D. and Morrison, A. A. (2019) Multigeneric resistance to monepantel on a UK sheep farm. Veterinary Parasitology: X, 1, 100003. (doi: 10.1016/j.vpoa.2019.100003)

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The amino acetonitrile derivative, monepantel, represented the first new broad spectrum anthelmintic to be brought to market for use in sheep for over 25 years when it was introduced in 2009. This study characterised monepantel efficacy, using faecal egg count reduction and controlled efficacy tests, against gastrointestinal nematodes following a report of treatment failure in a UK lowland sheep flock. Twelve lambs were each artificially administered 15,000 infective larvae that had been propagated from lamb faeces collected from the farm of interest. The controlled efficacy test showed that a recommended dose rate of monepantel (2.5 mg/kg body weight) administered at day 28 post infection was ineffective at removing the infection in the treated lambs. The result demonstrated simultaneous resistance to monepantel in Teladorsagia circumcincta, Trichostrongylus vitrinus and Oesophagostomum venulosum with efficacies based on adult worm burden reductions, compared to untreated controls, of 78%, 27% and 22% respectively. Monepantel efficacy based on undifferentiated egg count in treated animals, seven day post administration, compared to untreated controls was 85%. The results raise questions about the origins of, and predisposing factors for, resistance development in the three different species, and reinforces the value of differentiating post treatment faecal egg counts to genus or species level.

Item Type:Articles
Additional Information:The authors gratefully acknowledge funding from The Scottish Government’s Rural and Environment Science and Analytical Services Division (RESAS).
Glasgow Author(s) Enlighten ID:Hamer, Miss Kim
Authors: Bartley, D. J., Hamer, K., Andrews, L., Sargison, N. D., and Morrison, A. A.
College/School:College of Medical Veterinary and Life Sciences > School of Veterinary Medicine
Journal Name:Veterinary Parasitology: X
Published Online:16 February 2019
Copyright Holders:Copyright © 2019 Elsevier B.V.
First Published:First published in Veterinary Parasitology: X 100003
Publisher Policy:Reproduced under a Creative Commons License

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