Gaba S, Cabaret J, Ginot V, Silvestre A
INRA, Research Unit Biometry, Domaine Saint-Paul - Site Agroparc 84914 Avignon Cedex 9, France.
Parasitology. 2006 Sep;133(Pt 3):345-56. doi: 10.1017/S0031182006000503. Epub 2006 Jun 9.
We have developed an individual-based model to reflect the complexity of the early phase of drug resistance selection in a nematode/sheep model. The infection process consists of the stochastic ingestion of infective larvae spatially aggregated in clumps. Each clump corresponds to infective larvae, which are the offspring of the mature nematodes from a given sheep. We studied the dynamics of the parasitic population and the frequency of the recessive resistance alleles during selection by anthelmintic treatments. The interaction between genetic and demographic processes illustrated the trade-off between the control of the infection and the delay of resistance selection. We confirmed the importance of the number of treatments and their timing. The same treatment frequency may result in different outcomes on resistance selection in relation to the size of the refuge (infective larvae on pasture). Treatment applied during the summer (when the mortality of infective larvae on pasture was high), may lead to a rapid selection of drug resistance and a lack of control of sheep and pasture contamination. We showed that higher stocking rates were also a force in promoting the resistance allele selection.
我们开发了一种基于个体的模型，以反映线虫/绵羊模型中耐药性选择早期阶段的复杂性。感染过程包括随机摄入在空间上聚集成团的感染性幼虫。每个团块对应于感染性幼虫，它们是来自特定绵羊的成熟线虫的后代。我们研究了驱虫治疗选择过程中寄生虫种群的动态以及隐性耐药等位基因的频率。遗传和种群统计学过程之间的相互作用说明了在控制感染和延缓耐药性选择之间的权衡。我们证实了治疗次数及其时机的重要性。相同的治疗频率可能因避难所（牧场上的感染性幼虫）的大小而导致耐药性选择的不同结果。在夏季（此时牧场上感染性幼虫的死亡率很高）进行治疗，可能会导致耐药性的快速选择以及对绵羊和牧场污染缺乏控制。我们表明，较高的放养率也是促进耐药等位基因选择的一个因素。
