Wastewater and public health: the potential of wastewater surveillance for monitoring COVID-19

Monitoring SARS-CoV-2 circulation and diversity through community wastewater sequencing

“…The majority of the mutations (132/145) listed inSupplementary Table S2have a coverage of at least 30X, which produces an error rate of 1 in 585,000 nucleotides sequenced30 .The use of sewage as a tool to understand the epidemiology and diversity of SARS-CoV-2 at a community level offers many advantages over human sampling. Sewage samples are relatively easy to collect, because no invasive sampling is required, there is no sampling bias towards sequences from moderate and severe cases, there are limited ethical issues, and potentially few samples are required to give a picture of the temporal changes of viral infections in the community28,29 . Nevertheless, comprehensive comparisons with clinical surveillance and other epidemiological approaches are required to determine the extent and limits of using sewage as a surveillance/early warning tool.…”

How to study SARS-CoV-2 in soils?

“…Taking into account that, up to now, no peer-reviewed paper focusing on SARS-CoV-2 in sewage sludge has been published, even if some comments have been presented in few peer-reviewed publications ( Carraturo et al, 2020 ; Farkas et al, 2020b ), and no peer-reviewed paper has been published dealing with the detection, determination or quantification of SARS-CoV-2 in soils (with just three papers putting together soils and SARS-CoV-2 – Lal et al, 2020 ; Núñez-Delgado, 2020b ; Steffan et al, 2020 ), in this discussion piece we would propose a methodological approach in order to define some steps to follow for studying this virus (and even other pathogenic microorganisms) in soils and soil-related samples.…”

“…As possible answers, regarding concentration and subsequent steps to finally quantify SARS-CoV-2, the procedures reviewed and commented in Farkas et al (2020b) for water and sludge could be considered for soil-related liquid samples (lixiviates/leachates, liquids from catchers, runoff samples, soil solution), and for solid soil samples, respectively, even if more specific procedures could be assayed and further refined for the soil environment.…”

“…To take into account that the manuscripts commented by Farkas et al (2020b) regarding SARS-CoV-2 in sewage sludge were preprints still not subjected to peer review at the time of the publication, so, to be seen with precaution as could be not published as were at that moment. Any case, Farkas et al (2020b) indicate that “sludge samples were either subject to RNA extraction directly, or viruses were eluted and PEG precipitated from the matrix”, and then give further details, most of them for wastewater, but overall interesting as starting point for eventual future developments of methods eventually applicable to soil samples. Maybe, in the future, some of the preprints considered by these authors could be finally accepted and published, and then we, as all interested in performing procedures for different solid matrix (included soils), could take into account all those additional details.…”

The role of wastewater treatment plants as tools for SARS-CoV-2 early detection and removal

“…It potentially provides real time information on wastewater contaminants [ 72 ] and was first used in 2001 to evaluate illicit drug usage [ 73 ]. More recently, WBE has been proposed for the early detection of viral outbreaks [ [74] , [75] , [76] , [77] , [78] , [79] , [80] , [81] , [82] ] as well as for the persistence of viral indicators in the aquatic environment [ 75 , 83 ]. The methods used are high throughput RNA sequencing (RNA-Seq) more commonly than PCR (qRT-PCR) [ 75 , 84 ].…”