Echevarria F A, Armour J, Duncan J L
Department of Veterinary Parasitology, University of Glasgow, UK.
Vet Parasitol. 1991 Aug;39(3-4):279-84. doi: 10.1016/0304-4017(91)90044-v.
Following evidence of reduced efficacy of ivermectin in a field population of Haemonchus contortus in Brazil, this strain of the parasite was submitted to a controlled anthelmintic test. Eighty worm-free lambs were randomly split into two groups of 40. Each lamb in the first group was infected with 5000 third stage larvae (L3) of the ivermectin-resistant strain; the remaining 40 lambs were each infected with 5000 L3 of a H. contortus strain of known susceptibility to the major groups of anthelmintic compounds used in sheep. On Day 28 post-infection, each group was subdivided according to egg counts and at random into four sub-groups of ten lambs, each of which was treated with albendazole (ABZ) at 3.8 mg kg-1, levamisole (LEV) at 7.5 mg kg-1 or ivermectin (IVM) at 0.2 mg kg-1, or was left as untreated control. At slaughter, 7 days later, all the anthelmintics reduced worm burdens in animals infected with the susceptible strain (ABZ 98.9%, LEV and IVM 100%). By contrast, in the lambs infected with the ivermectin-resistant strain, LEV was 99.8% effective, but ABZ reduced worm counts by only 14.7% and IVM by only 10.4%. Interestingly at necropsy on Day 7 post-treatment, the egg counts in the resistant strain treated with ABZ had been reduced by 92.5%, although worm counts were reduced by only 14.7%.(ABSTRACT TRUNCATED AT 250 WORDS)
在巴西，有证据表明伊维菌素对捻转血矛线虫田间种群的疗效降低，该寄生虫菌株因此接受了一项对照驱虫试验。80只无蠕虫羔羊被随机分成两组，每组40只。第一组的每只羔羊感染5000条伊维菌素抗性菌株的三期幼虫（L3）；其余40只羔羊每只感染5000条对绵羊使用的主要驱虫化合物组已知敏感的捻转血矛线虫菌株的L3。感染后第28天，根据虫卵计数将每组再随机细分为四个亚组，每组十只羔羊，分别用3.8毫克/千克的阿苯达唑（ABZ）、7.5毫克/千克的左旋咪唑（LEV）或0.2毫克/千克的伊维菌素（IVM）进行治疗，或作为未治疗对照。7天后屠宰时，所有驱虫药都降低了感染敏感菌株动物的蠕虫负荷（ABZ为98.9%，LEV和IVM为100%）。相比之下，在感染伊维菌素抗性菌株的羔羊中，LEV的有效性为99.8%，但ABZ仅使蠕虫数量减少14.7%，IVM仅减少10.4%。有趣的是，在治疗后第7天尸检时，用ABZ治疗的抗性菌株中的虫卵计数减少了92.5%，尽管蠕虫数量仅减少了14.7%。（摘要截断于250字）
