Yeager C, Tucker M, Gutierrez A, O'Brien C, Sharma M, Fournet V, Dubey J P, Jenkins M, Kniel K, Rosenthal B M
Animal Parasitic Diseases Laboratory, Beltsville Agricultural Research Center, North East Area, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD 20705, USA.
Environmental Microbial and Food Safety Laboratory, Beltsville Agricultural Research Center, North East Area, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD 20705, USA.
Food Waterborne Parasitol. 2024 Aug 31;37:e00243. doi: 10.1016/j.fawpar.2024.e00243. eCollection 2024 Dec.
Irrigation water contaminated by human fecal material may elevate the risk of produce contamination with the enteric parasite Oocysts of are resistant to commonly used disinfectants and a method of removing from irrigation water would mitigate this risk. We evaluated zero valent iron (ZVI) sand filtration as one such method. We sought to determine if sand filters containing ZVI outperformed those without ZVI. We first evaluated the abundant poultry parasites , and as surrogates for . We determined if a miniaturized gravity fed ZVI-sand filter, scaled to evaluate scarce supplies of oocysts, provided useful information about the performance of larger filtration systems. Filters were inoculated with oocysts, rinsed, and the resulting filtrate examined microscopically for oocysts. We performed experiments to measure the effect of varying ZVI concentrations, repeated filter use, simulated agricultural water, and oocyst size and condition. We then compared the performance of mini filters to that of larger, gravity-fed pool filters and found that ZVI-sand filtration was far more effective at removing spp. from water when compared to sand filtration, at both scales. Sand mini filters retained 13-54 % of oocysts, and pool filters retained 82 %, but when combined with 50 % (mini filter) or 35 % (pool filter) /v ZVI, mini filters retained 89-99 % of oocysts and pool filters retained >99 %. The effectiveness of the mini filters increased with increasing ZVI concentration, and the addition of ZVI far outweighed the influence of any other measured variable. We then performed experiments including , which provided similar results to those utilizing ; 59 % of inoculated oocysts were retained in sand mini filters, and 97 % in mini filters composed of 35 % /v ZVI. In sum, ZVI is highly effective in removing oocysts from water and is a useful surrogate for to assess filtration. ZVI-sand filtration shows promise as a tool to mitigate the risk of contamination of irrigation water. Further studies should evaluate the performance of ZVI-sand in pressurized fast filtration systems under a range of field conditions.
受人类粪便污染的灌溉水可能会增加农产品被肠道寄生虫污染的风险。隐孢子虫的卵囊对常用消毒剂具有抗性，而从灌溉水中去除隐孢子虫的方法可以降低这种风险。我们评估了零价铁（ZVI）砂滤作为一种这样的方法。我们试图确定含有ZVI的砂滤器是否比不含ZVI的砂滤器表现更好。我们首先评估了丰富的家禽寄生虫——贝氏隐孢子虫、微小隐孢子虫和火鸡隐孢子虫——作为隐孢子虫的替代物。我们确定了一个小型重力供料的ZVI砂滤器（按比例缩小以评估稀缺的隐孢子虫卵囊供应）是否能提供有关更大过滤系统性能的有用信息。将卵囊接种到滤器中，冲洗后，对所得滤液进行显微镜检查以检测卵囊。我们进行了实验，以测量不同ZVI浓度、滤器重复使用、模拟农业用水以及卵囊大小和状况的影响。然后，我们将小型滤器的性能与更大的重力供料泳池滤器的性能进行了比较，发现与砂滤相比，在两个规模上，ZVI砂滤在从水中去除隐孢子虫属方面都要有效得多。小型砂滤器保留了13% - 54%的隐孢子虫卵囊，泳池滤器保留了82%，但当与50%（小型滤器）或35%（泳池滤器）的ZVI/v混合时，小型滤器保留了89% - 99%的卵囊，泳池滤器保留了>99%。小型滤器的有效性随着ZVI浓度的增加而提高，并且ZVI的添加远远超过任何其他测量变量的影响。然后我们进行了包括微小隐孢子虫的实验，其结果与使用贝氏隐孢子虫的实验结果相似；59%接种的微小隐孢子虫卵囊保留在小型砂滤器中，97%保留在由35%的ZVI/v组成的小型滤器中。总之，ZVI在从水中去除卵囊方面非常有效，并且微小隐孢子虫是评估过滤时隐孢子虫的有用替代物。ZVI砂滤显示出作为减轻灌溉水污染隐孢子虫风险工具的前景。进一步的研究应评估ZVI砂在一系列田间条件下的加压快速过滤系统中的性能。
