Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Königsweg 67, 14163 Berlin, Germany.
Parasitol Res. 2012 Mar;110(3):1159-64. doi: 10.1007/s00436-011-2606-y. Epub 2011 Sep 7.
The estimation of parasitic nematode larvae present on pasture is an important tool applied in many epidemiological studies. In the face of climatic changes, there is increased interest in identifying parameters influencing the survival of free-living stages of parasites under different meteorological conditions. In order to predict possible risk factors for grazing livestock, reliable and reproducible methods to assess the density of larvae on pasture are required. A laboratory method for the recovery of strongylid third-stage larvae from herbage samples was developed, standardised and its efficacy assessed in controlled experiments as well as under field conditions. Grass samples free of any nematode larvae were used and inoculated with known numbers of third-stage larvae of Cooperia oncophora in different concentrations. The grass samples were inoculated with larvae over 24 h, followed by soaking for 4 h. The recovery process included washing over sieves and centrifugation of the obtained liquid. The total time required for the recovery process was about 5-7 h (excluding inoculation). Recovery rates range from 68% to 98% and a strong correlation between numbers of larvae added to the grass samples and numbers of larvae that could be recovered was observed (p < 0.001). The new method proved to be reproducible and provides high recovery rates combined with the potential to handle many samples simultaneously in a relatively short time, thus offering high throughput opportunities applicable to field experiments.
对牧场上寄生线虫幼虫的估计是许多流行病学研究中应用的重要工具。面对气候变化，人们越来越关注在不同气象条件下识别影响寄生虫自由生活阶段生存的参数。为了预测放牧牲畜的可能风险因素，需要可靠和可重复的方法来评估牧场上幼虫的密度。本研究开发了一种从牧草样本中回收强旋尾线虫第三期幼虫的实验室方法，对其进行了标准化，并在控制实验和野外条件下评估了其功效。使用不含任何线虫幼虫的草样，并以不同浓度接种已知数量的无齿食道口线虫第三期幼虫。草样在接种幼虫后浸泡 24 小时，然后浸泡 4 小时。回收过程包括用筛子冲洗和对获得的液体进行离心。回收过程总共需要约 5-7 小时（不包括接种）。回收率范围为 68%至 98%，并且观察到添加到草样中的幼虫数量与可回收的幼虫数量之间存在很强的相关性（p<0.001）。新方法被证明是可重复的，并提供了高回收率，同时具有在相对较短的时间内同时处理多个样本的潜力，从而为适用于野外实验的高通量提供了机会。
