Evidence for reversion towards anthelmintic susceptibility in Teladorsagia circumcincta in response to resistance management programmes

摘要: Maintaining production and economic viability in the face of resistance to multiple anthelmintic actives is a challenge for farmers many countries. In this situation, most New Zealand rely on use combination products, containing with similar spectra activity, order maintain control. However, there are concerns that combinations, once has already developed individual actives, could rapidly lead complete failure all actives. This study followed seven farms, previously diagnosed at least two classes anthelmintic, which were implementing tailored programme ‘best practice parasite management’. The aim was ascertain whether programmes, included almost exclusive anthelmintics, able prevent from developing further. Strategies implemented each farm varied, but had consistent underlying principles i.e. avoid over-use anthelmintics; minimise susceptible stock; refugia susceptibility ensure only effective anthelmintics used. Annual faecal egg count reduction tests (FECRT) undertaken lambs farms monitor efficacy over 5 years. albendazole, ivermectin levamisole calculated changes against Teladorsagia circumcincta assessed. Overall, significant improvement effectiveness both T. circumcincta, positive non-significant trend evidence reversion towards susceptibility. Hence, integrated other management strategies, did not result further development despite exhibiting outset. What-is-more, measured increases suggests adoption best strategies may extend useful life even after been diagnosed.