Purpose

Susceptibility and resistance of Haemonchus contortus to anthelmintic drugs, including ivermectin, levamisole, and albendazole in naturally infected sheep were investigated.

Methods

Three sets of assays were conducted to detect drug efficacy. Firstly, in vivo estimation of drug resistance to H. contortus was explored in 80 sheep naturally infected with H. contortus. Sheep were divided into four equal groups (20 sheep for each group): the first group was treated with albendazole (5.00 mg/kg BW), the second with levamisole (7.50 mg/kg BW), the third with ivermectin (0.20 mg/kg BW), and the fourth group served as the untreated control. Fecal egg reduction test (FERT) was done at days 7 and 14 after treatment. Secondly, for in vitro egg hatching assay (EHA), H. contortus eggs from naturally infected sheep were collected and treated with 0.0002, 0.002, 0.02, 0.2, and 2.0 µg/mL albendazole. Thirdly, molecular detection of the albendazole resistance gene in adult male H. contortus worms and larvae from infected sheep was carried out using allele-specific PCR.

Results

The FECRT results showed that the drug efficacy was 86.84% for albendazole and 100% for both levamisole and ivermectin. The result of EHA showed that eggs did not hatch at 2.0 µg/mL albendazole concentration. Molecular findings showed two forms, including H. contortus homozygous susceptible (SS) and heterozygous (RS) of “β-tubulin” gene at 200 sites, which were recorded in both single male worms and larvae.

Conclusion

H. contortus, which was susceptible to levamisole and ivermectin, had developed resistance to albendazole.

中文翻译：

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Haemonchus contortus 对自然感染埃及绵羊的抗蠕虫药的易感性和抗性。

目的

研究了旋毛虫对自然感染绵羊中伊维菌素、左旋咪唑和阿苯达唑等驱虫药的敏感性和耐药性。

方法

进行了三组测定以检测药物功效。首先，在80 只自然感染了扭曲变形杆菌的绵羊中探索了对扭曲变形杆菌耐药性的体内评估。羊被分成四组（每组 20 只羊）：第一组用阿苯达唑（5.00 毫克/公斤体重）治疗，第二组用左旋咪唑（7.50 毫克/公斤体重）治疗，第三组用伊维菌素（0.20 毫克/公斤体重）治疗。 kg BW)，第四组作为未处理的对照组。在治疗后第 7 天和第 14 天进行粪卵减少试验 (FERT)。其次，对于体外卵孵化试验（EHA），H. contortus收集自然感染绵羊的卵并用 0.0002、0.002、0.02、0.2 和 2.0 µg/mL 阿苯达唑处理。第三，使用等位基因特异性PCR对成年雄性扭曲型H. contortus蠕虫和感染绵羊幼虫中的阿苯达唑抗性基因进行分子检测。

结果

FECRT结果显示，阿苯达唑的药效为86.84%，左旋咪唑和伊维菌素的药效均为100%。EHA 的结果表明，在 2.0 µg/mL 阿苯达唑浓度下，鸡蛋没有孵化。分子发现显示两种形式，包括H. contortus纯合易感 (SS) 和“β-微管蛋白”基因在 200 个位点的杂合 (RS)，这在单个雄性蠕虫和幼虫中均有记录。

结论

H. contortus对左旋咪唑和伊维菌素敏感，已对阿苯达唑产生抗药性。