Abstract
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 90 and T 99 (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 90 values of 1.9 and 1.2 day and T 99 values of 6.4 and 4.0 days, respectively. When samples were filtered through 0.22 µm pore size membranes, T 90 values increased to 3.3 and 1.5 days, and T 99 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 90 values of 7.7 and 5.5 days, and T 99 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.
Keywords: SARS-CoV-2; persistence; temperature; viability; wastewater; water.
【저자키워드】 SARS-CoV-2, wastewater, persistence, viability, temperature, water, 【초록키워드】 COVID-19, pandemic, risk, SARS-CoV-2 virus, Risk assessment, wastewater, viability, Regression model, Patient, Urine, temperature, SARS-CoV-2 RNA, Quantitative, Plaque assay, COVID-19 patient, Faeces, microbial, COVID-19 transmission, water, Variability, effort, assumption, membranes, plaque assays, highlight, lowest, log, carried, remained, raised, required, exacerbated, adjusted, discharged, environmental condition, Determining, increases in, excrete, filtered, nonlinear regression,