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Research article2020Peer reviewed

First case of monepantel resistant nematodes of sheep in Sweden

Hoglund, Johan; Enweji, Nizar; Gustafsson, Katarina

Abstract

In this study, we describe for the first time monepantel (MOP) resistance in gastrointestinal nematodes (GIN) in a Swedish sheep flock. On the farm, which had recurrent problems with Haemonchus contortus infection, the efficacy of most available anthelmintics (AH) in Sweden (i.e. ivermectin, albendazole, levamisole and monepantel), was monitored. This was done with the faecal egg count reduction test (FECRT) on three different occasions between August 2017 and April 2020. Although, MOP was used in ewes for the first time in this herd in October 2018 and then demonstrated to be highly efficacious (100% reduction), MOP-resistant worms (52% reduction) appeared in lambs already in April 2020. Resistance was detected only after two further rounds of treatment of the lambs after weaning. It is assumed that a contributing factor to this extremely rapid development was related to the fact that ewes and lambs treated during the housing period were let out on clean pasture after treatment. The ewes were treated during the housing period 2018 and grazed a clean pasture the following spring. The same ewes were treated a second time after housing 2018. The lambs were grazed with these ewes in summer 2018 and after weaning they were treated and moved to another clean pasture during the fall 2018. Anthelmintic resistance was also confirmed on two occasions to different compounds of ivermectin and once to albendazole, but not to levamisole which was tested twice. In conclusion, this is the first description of triple resistance to AH drugs in GIN of sheep in Sweden.

Keywords

Anthelmintic resistance; Gastrointestinal nematodes; McMaster; Faecal egg count reduction test; Sheep

Published in

Veterinary Parasitology: Regional Studies and Reports
2020, Volume: 22, article number: 100479
Publisher: ELSEVIER

      SLU Authors

      • Associated SLU-program

      AMR: Parasite

      UKÄ Subject classification

      Clinical Science

      Publication identifier

      DOI: https://doi.org/10.1016/j.vprsr.2020.100479

      Permanent link to this page (URI)

      https://res.slu.se/id/publ/123120