“The paper lays out in great detail how we do everything—how to normalize the data for population and take care of different variants and things like that,” said USask toxicologist Dr. John Giesy (PhD), lead author of the paper published Feb. 23 in a special issue of the high-impact journal ACS ES&T Water.
The highly technical paper isn’t aimed at a general audience. Instead, it sets out the research team’s standard operating procedures for other scientists to follow, describing in detail how to sample the wastewater, perform analyses, ensure quality control, and perform the requisite calculations.
Along with Giesy, Dr. Markus Brinkmann (PhD) and Dr. Kerry McPhedran (PhD)—the public faces of the COVID-19 team for the past 18 months—the list of authors collaborating on the paper includes seven other USask researchers, Saskatoon’s wastewater plant operator, two scientists from the National Microbiology Lab in Winnipeg, and a researcher from the University of Waterloo.
Since the arrival of COVID-19 in Saskatchewan, results of USask’s wastewater analysis have been published online in a dashboard presented by a team at the university’s Global Institute for Water Security, with the most recent data indicating Saskatoon’s prevalence of infections at the highest rate ever.
“The key thing is we hear from public health that we are the only show in town, and that our numbers are extremely useful because, without testing and without isolating and contact tracing—all these things the province used to do—they have no other way to have any evidence of what’s going on,” said Giesy.
Brinkmann said “the Holy Grail” in wastewater analysis is to normalize the results to the general population, ensuring that the data accurately reflect what’s happening in the population.
During the first four waves of the pandemic, researchers could associate their virus load samples with the actual COVID-19 case numbers the province was reporting from PCR swab tests on individuals, with the samples acting as a leading indicator of infection rates by about one week. With the province no longer doing PCR confirmations of all positive cases, researchers for now are “hindcasting,” based on what they saw in the first four waves.
They also are investigating measuring what they term “markers of population” to calculate how many people were peeing and pooping into the wastewater stream on a particular day—using such indicators as the amount of artificial sweeteners from pop, caffeine, and ammonia from urine—and correlating it to the virus load.
The researchers were contacted a few weeks ago by Saskatchewan health officials, who wanted the wastewater analysis extended across the province from its current focus on Saskatoon, Prince Albert, North Battleford and two First Nations, Giesy said.
“We told them we shouldn’t be running a routine monitoring program,” he said. “It’s incumbent on us as university academic scientists to share that roadmap with the scientific community and transfer the technology. Health officials should be using that technology to do it or hiring a private contractor.”
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