Schweizer G, Braun U, Deplazes P, Torgerson P R
Department of Farm Animals, University of Zurich, Switzerland.
Vet Rec. 2005 Aug 13;157(7):188-93. doi: 10.1136/vr.157.7.188.
In dairy cattle in Switzerland, the prevalence of infection with Fasciola hepatica is over 16 per cent. Previous studies have suggested that even subclinical infections with liver fluke may induce significant reductions in the performance of cattle. The financial losses attributable to F hepatica were estimated using a simple spreadsheet model to sum the individual losses that have been suggested in the literature. Because there is substantial variability in these production losses, Monte Carlo sampling techniques were used to model this variability. Each cost item and each data item related to the prevalence of F hepatica was assigned a mathematical distribution which took account of the variability of the experimental data and/or the sample size of the data. A total of 10,000 simulations were undertaken, with each item randomly varied through its mathematical distribution on each simulation. The results suggest that the median financial loss due to bovine fasciolosis in Switzerland is approximately 52 million, with probable 95 per cent confidence limits ranging from 22 million to 92 million per annum, which represents a median loss of 299 per infected animal. Most of the losses arise from reduced milk yield and reduced fertility, and smaller losses are due to reduced meat production and the condemnation of livers.
在瑞士的奶牛中，肝片吸虫感染率超过16%。先前的研究表明，即使是肝吸虫的亚临床感染也可能导致奶牛生产性能显著下降。使用一个简单的电子表格模型来估算因肝片吸虫造成的经济损失，该模型汇总了文献中提到的个体损失。由于这些生产损失存在很大差异，因此使用蒙特卡罗抽样技术对这种差异进行建模。与肝片吸虫感染率相关的每个成本项目和每个数据项目都被赋予了一个数学分布，该分布考虑了实验数据的变异性和/或数据的样本量。总共进行了10000次模拟，每次模拟中每个项目都通过其数学分布随机变化。结果表明，瑞士牛肝片吸虫病造成的经济损失中位数约为5200万，95%的置信区间可能为每年2200万至9200万，即每头感染动物的中位数损失为299。大部分损失来自产奶量下降和繁殖力降低，较小的损失则是由于肉类产量减少和肝脏被拒收。
