Székely, Anna
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
Research article2022Peer reviewedOpen access
Evaluating the Use of Alternative Normalization Approaches on SARS-CoV-2 Concentrations in Wastewater: Experiences from Two Catchments in Northern Sweden
Isaksson, Frida; Lundy, Lian; Hedstrom, Annelie; Szekely, Anna J.; Mohamed, Nahla
Abstract
The detection of SARS-CoV-2 RNA fragments in feces has paved the way for wastewater-based epidemiology to contribute to COVID-19 mitigation measures, with its use in a public health context still under development. As a way to facilitate data comparison, this paper explores the impact of using alternative normalization approaches (wastewater treatment plant (WWTP) flow, population size estimates (derived using total nitrogen (TN), total phosphorus (TP) and census data) and pepper mild mottle virus (PMMoV)) on the relationship between viral wastewater data and clinical case numbers. Influent wastewater samples were collected at two WWTPs in Lulea, northern Sweden, between January and March 2021. TN and TP were determined upon sample collection, with RNA analysis undertaken on samples after one freeze-thaw cycle. The strength of the correlation between normalization approaches and clinical cases differed between WWTPs (r <= 0.73 or r >= 0.78 at the larger WWTP and r <= 0.23 or r >= 0.43 at the smaller WWTP), indicating that the use of wastewater as an epidemiological tool is context-dependent. Depending on the normalization approach utilized, time-shifted analyses imply that wastewater data on SARS-CoV-2 RNA pre-dated a rise in clinical cases by 0-2 and 5-8 days, for the lager and smaller WWTPs, respectively. SARS-CoV-2 viral loads normalized to the population or PMMoV better reflect the number of clinical cases when comparing wastewater data between sewer catchments.
Keywords
wastewater-based epidemiology; normalization; population estimates; pepper mild mottle virus; clinical cases; infiltration inflow
Published in
Environments
2022, Volume: 9, number: 3, article number: 39
Publisher: MDPI
Mohamed, Nahala
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
SLU Authors
UKÄ Subject classification
Public Health, Global Health, Social Medicine and Epidemiology
Publication identifier
DOI: https://doi.org/10.3390/environments9030039
Permanent link to this page (URI)
https://res.slu.se/id/publ/123322