Exum Natalie G, Kosek Margaret N, Davis Meghan F, Schwab Kellogg J
Department of Environmental Health and Engineering, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205-2179, USA.
Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205-2179, USA.
Int J Environ Res Public Health. 2017 Aug 22;14(8):947. doi: 10.3390/ijerph14080947.
Empiric quantification of environmental fecal contamination is an important step toward understanding the impact that water, sanitation, and hygiene interventions have on reducing enteric infections. There is a need to standardize the methods used for surface sampling in field studies that examine fecal contamination in low-income settings. The dry cloth method presented in this manuscript improves upon the more commonly used swabbing technique that has been shown in the literature to have a low sampling efficiency. The recovery efficiency of a dry electrostatic cloth sampling method was evaluated using and then applied to household surfaces in Iquitos, Peru, where there is high fecal contamination and enteric infection. Side-by-side measurements were taken from various floor locations within a household at the same time over a three-month period to compare for consistency of quantification of bacteria. The dry cloth sampling method in the laboratory setting showed 105% (95% Confidence Interval: 98%, 113%) recovery efficiency off of the cloths. The field application demonstrated strong agreement of side-by-side results (Pearson correlation coefficient for dirt surfaces was 0.83 ( < 0.0001) and 0.91 ( < 0.0001) for cement surfaces) and moderate agreement for results between entrance and kitchen samples (Pearson (0.53, < 0.0001) and weighted Kappa statistic (0.54, < 0.0001)). Our findings suggest that this method can be utilized in households with high bacterial loads using either continuous (quantitative) or categorical (semi-quantitative) data. The standardization of this low-cost, dry electrostatic cloth sampling method can be used to measure differences between households in intervention and non-intervention arms of randomized trials.
对环境粪便污染进行经验性量化是了解水、环境卫生和个人卫生干预措施对减少肠道感染影响的重要一步。有必要规范实地研究中用于表面采样的方法，这些研究旨在调查低收入环境中的粪便污染情况。本手稿中提出的干布法改进了文献中显示采样效率较低的更常用的擦拭技术。使用[具体内容缺失]评估了干静电布采样方法的回收效率，然后将其应用于秘鲁伊基托斯的家庭表面，该地粪便污染和肠道感染程度较高。在三个月的时间里，同时从一个家庭内的不同楼层位置进行并排测量，以比较细菌定量的一致性。实验室环境中的干布采样方法显示，从布上回收的效率为105%（95%置信区间：98%，113%）。现场应用表明，并排结果具有很强的一致性（污垢表面的皮尔逊相关系数为0.83（<0.0001），水泥表面为0.91（<0.0001）），入口和厨房样本之间的结果具有中等一致性（皮尔逊相关系数为0.53（<0.0001），加权卡帕统计量为0.54（<0.0001））。我们的研究结果表明，该方法可用于细菌载量较高的家庭，使用连续（定量）或分类（半定量）数据。这种低成本的干静电布采样方法的标准化可用于测量随机试验中干预组和非干预组家庭之间的差异。
