Biochemistry and Immunology Department, Federal University of Minas Gerais (UFMG), Belo Horizonte, Minas Gerais, Brazil.
Deparment of Sanitary and Environmental Engineering Department, Federal University of Minas Gerais (UFMG), Belo Horizonte, Minas Gerais, Brazil.
Water Res. 2021 May 1;195:117002. doi: 10.1016/j.watres.2021.117002. Epub 2021 Mar 3.
COVID-19 patients can excrete viable SARS-CoV-2 virus via urine and faeces, which has raised concerns over the possibility of COVID-19 transmission via aerosolized contaminated water or via the faecal-oral route. These concerns are especially exacerbated in many low- and middle-income countries, where untreated sewage is frequently discharged to surface waters. SARS-CoV-2 RNA has been detected in river water (RW) and raw wastewater (WW) samples. However, little is known about SARS-CoV-2 viability in these environmental matrices. Determining the persistence of SARS-CoV-2 in water under different environmental conditions is of great importance for basic assumptions in quantitative microbial risk assessment (QMRA). In this study, the persistence of SARS-CoV-2 was assessed using plaque assays following spiking of RW and WW samples with infectious SARS-CoV-2 that was previously isolated from a COVID-19 patient. These assays were carried out on autoclaved RW and WW samples, filtered (0.22 µm) and unfiltered, at 4 °C and 24 °C. Linear and nonlinear regression models were adjusted to the data. The Weibull regression model achieved the lowest root mean square error (RMSE) and was hence chosen to estimate T and T (time required for 1 log and 2 log reductions, respectively). SARS-CoV-2 remained viable longer in filtered compared with unfiltered samples. RW and WW showed T values of 1.9 and 1.2 day and T values of 6.4 and 4.0 days, respectively. When samples were filtered through 0.22 µm pore size membranes, T values increased to 3.3 and 1.5 days, and T increased to 8.5 and 4.5 days, for RW and WW samples, respectively. Remarkable increases in SARS-CoV-2 persistence were observed in assays at 4 °C, which showed T values of 7.7 and 5.5 days, and T values of 18.7 and 17.5 days for RW and WW, respectively. These results highlight the variability of SARS-CoV-2 persistence in water and wastewater matrices and can be highly relevant to efforts aimed at quantifying water-related risks, which could be valuable for understanding and controlling the pandemic.
新冠病毒（SARS-CoV-2）感染者的尿液和粪便中可排出具有感染力的病毒，这引发了人们对新冠病毒是否可能通过气溶胶污染的水或粪-口途径传播的担忧。在许多中低收入国家，未经处理的污水经常被排放到地表水，这些担忧尤其严重。河流水（RW）和原污水（WW）样本中已检测到 SARS-CoV-2 的 RNA。然而，对于 SARS-CoV-2 在这些环境基质中的生存能力知之甚少。确定 SARS-CoV-2 在不同环境条件下在水中的持久性对于定量微生物风险评估（QMRA）中的基本假设非常重要。在这项研究中，通过用从一名 COVID-19 患者中分离出的具有感染性的 SARS-CoV-2 对 RW 和 WW 样本进行接种，使用噬斑测定法评估了 SARS-CoV-2 的持久性。在 4°C 和 24°C 下，对经过高压灭菌的 RW 和 WW 样本、经过过滤（0.22 µm）和未过滤的样本进行了这些测定。对数据进行了线性和非线性回归模型拟合。Weibull 回归模型达到了最低的均方根误差（RMSE），因此被选择用于估计 T 和 T（分别为 1 对数和 2 对数减少所需的时间）。过滤后的样本中 SARS-CoV-2 的存活时间长于未过滤的样本。RW 和 WW 的 T 值分别为 1.9 和 1.2 天，T 值分别为 6.4 和 4.0 天。当用 0.22 µm 孔径的膜对样本进行过滤时，RW 和 WW 的 T 值分别增加到 3.3 和 1.5 天，T 值分别增加到 8.5 和 4.5 天。在 4°C 下进行的测定中，SARS-CoV-2 的存活时间显著增加，RW 和 WW 的 T 值分别为 7.7 和 5.5 天，T 值分别为 18.7 和 17.5 天。这些结果突出表明了 SARS-CoV-2 在水和废水基质中的持久性存在差异，这对于量化与水相关的风险的努力非常重要，这对于了解和控制大流行可能具有重要意义。
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