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. 2023 Feb 20:860:160498.
doi: 10.1016/j.scitotenv.2022.160498. Epub 2022 Nov 25.

Quantification of SARS-CoV-2 in wastewater samples from hospitals treating COVID-19 patients during the first wave of the pandemic in Brazil

Juliana Calábria de Araújo  1 , Camila L Madeira  2 , Thiago Bressani  2 , Cíntia Leal  2 , Deborah Leroy  2 , Elayne C Machado  2 , Luyara A Fernandes  2 , Maria Fernanda Espinosa  2 , Gabriel Tadeu O Freitas  2 , Thiago Leão  2 , Vera Tainá Mota  2 , Alyne Duarte Pereira  2 , Carlos Perdigão  3 , Flávio Tröger  3 , Sérgio Ayrimoraes  3 , Marilia Carvalho de Melo  4 , Filipe Laguardia  5 , Marcus Tulius P Reis  6 , César Mota  2 , Carlos A L Chernicharo  2
Affiliations

Quantification of SARS-CoV-2 in wastewater samples from hospitals treating COVID-19 patients during the first wave of the pandemic in Brazil

Juliana Calábria de Araújo et al. Sci Total Environ. .

Abstract

The COVID-19 pandemic has caused a global health crisis, and wastewater-based epidemiology (WBE) has emerged as an important tool to assist public health decision-making. Recent studies have shown that the SARS-CoV-2 RNA concentration in wastewater samples is a reliable indicator of the severity of the pandemic for large populations. However, few studies have established a strong correlation between the number of infected people and the viral concentration in wastewater due to variations in viral shedding over time, viral decay, infiltration, and inflow. Herein we present the relationship between the number of COVID-19-positive patients and the viral concentration in wastewater samples from three different hospitals (A, B, and C) in the city of Belo Horizonte, Minas Gerais, Brazil. A positive and strong correlation between wastewater SARS-CoV-2 concentration and the number of confirmed cases was observed for Hospital B for both regions of the N gene (R = 0.89 and 0.77 for N1 and N2, respectively), while samples from Hospitals A and C showed low and moderate correlations, respectively. Even though the effects of viral decay and infiltration were minimized in our study, the variability of viral shedding throughout the infection period and feces dilution due to water usage for different activities in the hospitals could have affected the viral concentrations. These effects were prominent in Hospital A, which had the smallest sewershed population size, and where no correlation between the number of defecations from COVID-19 patients and viral concentration in wastewater was observed. Although we could not determine trends in the number of infected patients through SARS-CoV-2 concentrations in hospitals' wastewater samples, our results suggest that wastewater monitoring can be efficient for the detection of infected individuals at a local level, complementing clinical data.

Keywords: COVID-19 surveillance; COVID-19-positive patients; Hospital wastewater; SARS-CoV-2 monitoring; Wastewater-based epidemiology.

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Conflict of interest statement

Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Unlabelled Image
Graphical abstract
Fig. 1
Fig. 1
Map showing the city of Belo Horizonte in the State of Minas Gerais, Brazil. Created with mapchart.net.
Fig. 2
Fig. 2
Number of confirmed cases of COVID-19 per week from May 19 to August 5, 2020, in the city of Belo Horizonte reported by the municipal administration (source: https://prefeitura.pbh.gov.br/saude/coronavirus).
Fig. 3
Fig. 3
Number of confirmed cases of COVID-19 and viral concentration detected in wastewater samples (genes N1 and N2) from three different hospitals over time. Results for Hospital C on 3-Jul-2020 were negative, meaning that the sample did not amplify for CT < 40, according to CDC (2020). **No analysis performed. *No results reported for gene N2 on 5-Aug-2020.
Fig. 4
Fig. 4
Correlation between number of confirmed COVID-19 cases and viral concentration in wastewater samples from three different hospitals.
Fig. 5
Fig. 5
Correlation between total number of defecations by COVID-19 patients and SARS-CoV-2 concentration and load in Hospital A.
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