Maingi N, Bjørn H, Thamsborg S M, Bøgh H O, Nansen P
Danish Centre for Experimental Parasitology, Royal Veterinary and Agricultural University, Frederiksberg, Denmark.
Vet Parasitol. 1996 Nov 1;66(1-2):53-66. doi: 10.1016/s0304-4017(96)01006-0.
The occurrence of anthelmintic resistance in 15 goat herds in Denmark was investigated using the faecal egg count reduction test (FECRT), egg hatch assay (EHA) for thiabendazole (TBZ) and a microlarval development assay (LDA) for TBZ, levamisole (LEV) and ivermectin (IVM). Resistance to both benzimidazole (BZ) and levamisole (LEV) anthelmintics was detected on six farms, and to both BZs and IVM on one farm. Resistance to BZs was also detected on two farms and to LEV on two farms. Ivermectin resistance was present on one farm. Trichostrongylus and Ostertagia spp. were the predominant nematode species in both pre-treatment and post-treatment faecal cultures. In all nine instances where BZ resistance was detected in the FECRT, the LD50 values for TBZ in the EHA were higher than 0.5 microM TBZ (0.1 microgram TBZ/ml), indicating resistance. LD50 values for TBZ in the LDA were also higher than 0.5 microM where resistance to BZs was detected in the FECRT, except two farms where LD50 values of 0.21 and 0.29 microM TBZ were recorded. LD50 values in the LDA for isolates declared resistant to LEV ranged from 0.78 to 5.62 microM LEV. For IVM, the two resistant isolates had LD50 values of 25 and 68 nM IVM. There were disagreements in the declaration of resistance between methods of calculating faecal egg count reduction percentage (FECR%) based on the arithmetic mean and those where geometric mean EPG is used. Similarly, inclusion of pre-treatment EPG or control group EPG in the calculation of FECR% influenced declaration of resistance.
采用粪便虫卵计数减少试验（FECRT）、噻苯达唑（TBZ）的虫卵孵化试验（EHA）以及TBZ、左旋咪唑（LEV）和伊维菌素（IVM）的微幼虫发育试验（LDA），对丹麦15个山羊群中抗蠕虫药耐药性的发生情况进行了调查。在6个农场检测到对苯并咪唑（BZ）和左旋咪唑（LEV）类驱虫药均耐药，在1个农场检测到对BZ类和IVM均耐药。在2个农场检测到对BZ类耐药，在2个农场检测到对LEV耐药。在1个农场存在伊维菌素耐药。毛圆线虫属和奥斯特他线虫属是治疗前和治疗后粪便培养物中的主要线虫种类。在FECRT中检测到BZ耐药的所有9个案例中，EHA中TBZ的半数致死剂量（LD50）值高于0.5微摩尔TBZ（0.1微克TBZ/毫升），表明存在耐药性。在FECRT中检测到对BZ类耐药时，LDA中TBZ的LD50值也高于0.5微摩尔，除了2个农场记录的LD50值为0.21和0.29微摩尔TBZ。LDA中对声明对LEV耐药的分离株的LD50值范围为0.78至5.62微摩尔LEV。对于IVM，两个耐药分离株的LD50值分别为25和68纳摩尔IVM。基于算术平均值计算粪便虫卵计数减少百分比（FECR%）的方法与使用几何平均每克粪便虫卵数（EPG）的方法在耐药声明上存在分歧。同样，在FECR%的计算中纳入治疗前EPG或对照组EPG会影响耐药声明。
