USask wastewater analysis gave head start to health officials on COVID-19 spike


A University of Saskatchewan (USask) ecotoxicologist says researchers can give health officials at least a week’s notice on changes in the COVID-19 trend line through early detection in wastewater that may capture asymptomatic or pre-symptomatic cases.

The wastewater surveillance approach is about comparing trends in test cases with wastewater virus concentrations, according to the USask research team. They measure SARS-CoV-2 virus environmental degradation and count the number of copies of an RNA sequence specific to SARS-CoV-2 to establish a total concentration of virus in the sample.

“Based on the latest data, which shows the trend line is going up, I am predicting we will see a rise in cases for the next couple of weeks,” said USask ecotoxicologist John Giesy, who hopes his team’s wastewater data can give health officials a head start in the second wave of the pandemic. “We can also predict when outbreaks are declining, which will help planning for pandemic recovery,” he added.

Saskatchewan COVID-19 Numbers

These graphs show the wastewater surveillance data (red bars), which is a normalized virus load per 100 milliliters of wastewater, and the five-day moving average of new COVID-19 cases (green line), from Saskatchewan’s COVID-19 dashboard. The spike in cases in Saskatoon over mid-October was predicted by the model. Image credit: [USask]
Image credit: [USask]
As of November 9, Saskatchewan has about 4,087 active COVID-19 cases with approximately 434 located in Saskatoon. People who show up at COVID-19 testing stations are usually people with either symptoms or suspected COVID exposure, so the USask team is looking to wastewater to provide broader data for infected residents who may be asymptomatic or pre-symptomatic.

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Giesy is working alongside post-doctoral researcher Yuwei Xie and USask engineering researcher Kerry McPhedran to capture COVID-19 information shed into feces, which they started doing in July at Saskatoon’s wastewater treatment plant. There, samples are automatically collected over a 24-hour period and pumped into a refrigerator for preservation. Before the wastewater is released into the environment, it is treated with UV lights, neutralizing any potential infective virus, the research team explains in a project description.

The sample is then brought to labs on campus where Xie undertakes a two- to three-day analysis of the purified wastewater. He counts the number of copies of an RNA sequence specific to SARS-CoV-2 to establish a total concentration of virus in the sample.

Giesey’s team, which remains in need of additional funding, produces data once per week and then shares it with Saskatoon health officials and the Saskatchewan Health Authority.

As the chart with this article illustrates, Gisey’s team performed wastewater tests on October 7, 16 and 21 and detected a surge in SARS-CoV-2 concentration before an uptick in newly-diagnosed cases.

Engineering graduate student Shahab Minaei and his supervisor Jafar Soltan are also part of the COVID-19 wastewater surveillance team.


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