Environmental and Occupational Hazards Control Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Department of Environmental Health Engineering, School of Public Health and Safety, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Environmental Research and Development, American Water Works, Delran, NJ, USA.
Sci Total Environ. 2021 Oct 10;790:148205. doi: 10.1016/j.scitotenv.2021.148205. Epub 2021 Jun 2.
Wastewater-based epidemiology (WBE) approaches to detect SARS-CoV-2 in municipal wastewater can provide unique information on the incidence or prevalence of COVID-19 in community. However, there are several technical challenges coupled with sewage sampling for SARS-CoV-2, including intermittent shedding of viruses, sampling time, volume, and frequency. Sampling schemes thus may need to be tailored to reach out highly sensitive, accurate, and reliable results. Herein, we compared the accuracy and threshold cycle (Ct) profiles of SARS-CoV-2 in Moore swabs, composite (16-h), and grab samples taken from sewage manholes (n = 17) at the Middle Eastern city of Tehran, Iran, on two occasions (November 2020 and May 2021). Samples were concentrated by polyethylene glycol precipitation and the corresponding Ct values for CDC 'N' and 'ORF1ab' assays were derived by means of real time RT-qPCR. Overall, the Moore swabs performed equal to samples composited over 16 h for qualitative monitoring, and 34/34 (100%) were positive for SARS-CoV-2. The 'N' assay showed the highest detection frequency as compared to 'ORF1ab'. The mean Moore swab Ct profiles were more consistent with 16 h composite sampling as compared with corresponding grab samples, providing hints as to the best sampling protocol to adopt when planning a sewage monitoring campaign particularly under WBE. Furthermore, our analyses on local differences showed somewhat higher virus copy numbers in the southern areas. The experimental design of this study revealed that the Moore swab and composite samples are more sensitive than grab samples, suggesting that the collection of grab samples may be inappropriate for characterizing total number of viral RNA copies in sewage samples. Given the transiently presence of human host-restricted infections such as SARS-CoV-2 and the simplicity and affordability of Moore swab, the method is well suited for disease surveillance in resource poor regions struggling with limited capacity for clinical testing.
基于污水的流行病学（WBE）方法可用于检测市政污水中的 SARS-CoV-2，从而为社区中 COVID-19 的发病率或流行率提供独特的信息。然而，对 SARS-CoV-2 进行污水采样时存在一些技术挑战，包括病毒间歇性脱落、采样时间、体积和频率。因此，采样方案可能需要进行定制，以获得高度敏感、准确和可靠的结果。在此，我们比较了在伊朗德黑兰市中东城市两次采样（2020 年 11 月和 2021 年 5 月）时，从污水井盖中采集的 Moore 拭子、复合（16 小时）和抓取样本中 SARS-CoV-2 的准确性和阈值循环（Ct）谱（n=17）。样品通过聚乙二醇沉淀浓缩，通过实时 RT-qPCR 得出针对 CDC'N'和'ORF1ab'检测的相应 Ct 值。总体而言，Moore 拭子在定性监测方面与 16 小时复合采样效果相当，34/34（100%）对 SARS-CoV-2 呈阳性。与'ORF1ab'相比，'N'检测显示出最高的检测频率。与相应的抓取样本相比，Moore 拭子的平均 Ct 谱更符合 16 小时复合采样，这为规划污水监测活动时采用最佳采样方案提供了提示，特别是在 WBE 下。此外，我们对本地差异的分析表明，南部地区的病毒拷贝数略高。本研究的实验设计表明，Moore 拭子和复合样本比抓取样本更敏感，这表明抓取样本的采集可能不适合表征污水样本中病毒 RNA 拷贝的总数。鉴于 SARS-CoV-2 等人类宿主受限感染的短暂存在，以及 Moore 拭子的简单性和可负担性，该方法非常适合资源匮乏地区的疾病监测，这些地区的临床检测能力有限。
