PDF(Pubmed)
Abstract：
Wastewater-based epidemiology (WBE) may be successfully used to comprehensively monitor and determine the scale and dynamics of some infections in the community. We monitored severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in raw wastewater samples from Porto Alegre, Southern Brazil. The samples were collected and analyzed every week between May 2020 to May 2021. Meanwhile, different social restrictions were applied according to the number of hospitalized patients in the region. Weekly samples were obtained from two wastewater treatment plants (WWTP), named Navegantes and Serraria. To determine the SARS-CoV-2 RNA titers in wastewater, we performed RT-qPCR analysis targeting the N gene (N1). The highest titer of SARS-CoV-2 RNA was observed between epidemiological weeks (EWs) 33-37 (August), 42-43 (October), 45-46 (November), 49-51 (December) in 2020, and 1-3 (January), 7-13 (February to March) in 2021, with viral loads ranging from 1 × 106-3 × 106 genomic copies/Liter. An increase in positive confirmed cases followed such high viral loads. Depending on the sampling method used, positive cases increased in 6-7 days and 15 days after the rise of viral RNA titers in wastewater, with composite sampling methods showing a lower time lag and a higher resolution on the analyses. The results showed a direct relation between strict social restrictions and the loads of detected RNA reduction in wastewater, corroborating the number of confirmed cases. Differences in viral loads between different sampling points and methods were observed, as composite samples showed more stable results during the analyzed period. Besides, viral loads obtained from samples collected at Serraria WWTP were consistently higher than the ones obtained at Navegantes WWTP, indicating differences in local dynamics of SARS-CoV-2 spread in different regions of Porto Alegre. In conclusion, wastewater sampling to monitor SARS-CoV-2 is a robust tool to evaluate the viral loads contributing to hospitalized patients\' data and confirmed cases. In addition, SARS-CoV-2 detection in sewage may inform and alert the government when there are asymptomatic or non-tested patients.
摘要：
基于废水的流行病学（WBE）可以成功地用于全面监测和确定社区中某些感染的规模和动态。我们监测了阿雷格里港原废水样品中的严重急性呼吸综合征冠状病毒2（SARS-CoV-2）RNA，巴西南部。在2020年5月至2021年5月期间，每周收集和分析样本。同时,根据该地区住院患者的数量，采用不同的社会限制。每周从两个污水处理厂（WWTP）获得样品，名叫Navegantes和Serraria.为了确定废水中的SARS-CoV-2RNA滴度，我们进行了针对N基因（N1）的RT-qPCR分析。在流行病学周（EWs）33-37（8月）之间观察到SARS-CoV-2RNA的最高滴度，42-43（10月），45-46（11月），2020年49-51（12月）和1-3（1月），7-13（2月至3月），病毒载量范围为1×106-3×106基因组拷贝/升。在如此高的病毒载量之后，阳性确诊病例的增加。根据使用的抽样方法，阳性病例在废水中病毒RNA滴度升高后6-7天和15天增加，复合采样方法显示出较低的时滞和较高的分析分辨率。结果表明，严格的社会限制与废水中检测到的RNA减少的负荷之间存在直接关系，证实确诊病例的数量。观察不同采样点和方法之间的病毒载量差异,因为复合样品在分析期间显示出更稳定的结果。此外,从SerrariaWWTP收集的样品获得的病毒载量始终高于NavegantesWWTP获得的病毒载量，表明SARS-CoV-2在阿雷格里港不同地区传播的局部动态差异。总之,用于监测SARS-CoV-2的废水采样是评估导致住院患者数据和确诊病例的病毒载量的可靠工具。此外,在污水中检测到SARS-CoV-2可能会在无症状或未经测试的患者时通知政府并向政府发出警报。
