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Modelling the short- and long-term impacts of drenching frequency and targeted selective treatment on the performance of grazing lambs and the emergence of anthelmintic resistance

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)780-791
Number of pages12
JournalParasitology
Volume140
Issue number6
DOIs
Publication statusPublished - May 2013

Abstract

Refugia-based treatment strategies aim to prolong anthelmintic efficacy by maintaining a parasite population unexposed to anthelmintics. Targeted selective treatment (TST) achieves this by treating only animals that will benefit most from treatment, using a determinant criterion (DC). We developed a mathematical model to compare various traits proposed as DC, and investigate impacts of TST and drenching frequency on sheep performance and anthelmintic resistance. Short term, decreasing the proportion of animals drenched reduced benefits of anthelmintic treatment, assessed by empty body weight (EBW), but decreased the rate of anthelmintic resistance development; each consecutive drenching had a reduced impact on average EBW and an increased impact on the rate of anthelmintic resistance emergences. The optimal DC was fecal egg count, maintaining the highest average EBW when reducing the proportion of animals drenched. Long-term, reducing the proportion of animals drenched had little impact on total weight gain benefits, across animals and years, whilst reducing drenching frequency increased it. Decreasing the frequency and proportion of animals drenched were both predicted to increase the duration of anthelmintic efficacy but reduce the total number of drenches administered before resistance was observed. TST and frequency of drenching may lead to different benefits in the short versus long term.

    Research areas

  • Teladorsagia circumcincta, GASTROINTESTINAL PARASITISM, OSTERTAGIA-CIRCUMCINCTA INFECTION, refugia, BETA-TUBULIN GENE, targeted selective treatment, simulation modelling, anthelmintic resistance, BENZIMIDAZOLE RESISTANCE, IN-SILICO EXPLORATION, NEMATODE INFECTIONS, FREE-LIVING STAGES, sheep, TELADORSAGIA-CIRCUMCINCTA, WORM CONTROL, VETERINARY IMPORTANCE

ID: 5889088