East Tennessee Clinical Research, Inc., Rockwood, TN 37854, USA.
Vet Parasitol. 2012 Apr 19;185(1):9-15. doi: 10.1016/j.vetpar.2011.10.009. Epub 2011 Oct 18.
Since 2002, selected populations of Parascaris equorum in several countries have been reported to survive treatment with macrocyclic lactone (M/L) anthelmintics. Clinical treatment failures are characterized by negligible fecal egg count reduction, but M/L resistance has been confirmed in ascarids by controlled efficacy testing. Resistance was selected by current parasite control practices for foals, which often include exclusive and excessively frequent use of M/L dewormers, thereby minimizing refugia within the host and in the environment. Chemical control of M/L-resistant isolates can be accomplished with pyrimidine and/or benzimidazole anthelmintics, but a few M/L-resistant populations have recently exhibited resistance to pyrantel pamoate as well. Some specimens of Oxyuris equi regularly survive treatment with macrocyclic lactones, but it is uncertain whether this constitutes resistance or merely confirms the incomplete oxyuricidal efficacy of virtually all broad spectrum equine anthelmintics. Variations in other biological parameters of Oxyuris and Parascaris, specifically atypical infection of older hosts and shorter prepatent periods, have been reported anecdotally. These changes may represent genetic modifications that have evolved in parallel with resistance as a result of anthelmintic selection pressure.
自 2002 年以来，据报道，一些国家的马副蛔虫种群对大环内酯类（M/L）驱虫药的治疗有一定的耐药性。临床治疗失败的特征是粪便虫卵减少可忽略不计，但通过对照疗效试验已确认驱虫药对蛔虫有耐药性。驱虫药耐药性是由目前针对小马驹的寄生虫控制措施选择的，这些措施通常包括频繁和过度使用大环内酯类驱虫药，从而最大限度地减少了宿主内和环境中的避难所。可以使用嘧啶和/或苯并咪唑类驱虫药来控制对 M/L 耐药的分离株，但最近有少数 M/L 耐药种群对吡喹酮也表现出耐药性。一些马蛔虫的样本通常能耐受大环内酯类药物的治疗，但这是否构成耐药性，或者仅仅证实了几乎所有广谱马驱虫药驱虫效果不完全，还不确定。马副蛔虫和马蛔虫的其他生物学参数也存在差异，特别是老年宿主的非典型感染和较短的潜伏期，这些差异已有一些零星报道。这些变化可能是由于驱虫药选择压力而产生的与耐药性平行进化的遗传修饰。
