Researchers look to our waste for clues about viral spread
By Caroline Barlott | May 3, 2022
Dr. Bonita Lee, an associate professor of pediatrics at the University of Alberta and co-lead for Alberta’s water monitoring, looks at a graph on her computer screen that shows the amount of SARS CoV-2 RNA in wastewater in various communities across the province. Edmonton’s graph at the time of publication starts out with several up and down waves reminiscent of those seen on a seismometer, eventually culminating in a big peak.
The information, made available to the public through Alberta’s COVID Tracker website, displays the work Lee and her colleagues have been analyzing over the course of the pandemic through the Pan Alberta Wastewater Monitoring Project.
When people have COVID-19, virus remnants are shed in their stool, ending up in wastewater. Samples of this waste-water are collected three times a week from 20 treatment plants or pump stations, covering 42 communities and cities. There are also site-specific waste-water management projects at chosen long-term care facilities, hospitals, university campuses and correctional facilities with data shared directly with those sites.
After samples are collected, they’re shipped to the U of A and University of Calgary where they are analyzed in the labs. The U of A and U of C teams use a real time quantitative RT-PCR (reverse transcription-polymerase chain reaction) test to detect and quantify the level of viral RNA in the sample. Both teams use different methods to process the waste water sample for the RT-PCR test. Within 24 to 48 hours, results are gathered and shared.
With the province restricting PCR tests to only those with risk for severe disease and those who live and work in high-risk settings, this data is critical and can influence public health action. “Everyone is waiting to see what will happen to COVID. So, I don’t have a crystal ball — there are too many elements changing how it spreads in the community,” says Lee. “But wastewater will actually capture anyone who is infected with COVID and shedding the virus in their stool. So, it is not biased and not selective and gives a better idea of how much disease is happening in the community for that particular wave.”
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Co-lead of the University of Alberta research, Xiao-Li (Lilly) Pang, says the infrastructure for the project dates back to 2007. At that time, the team was studying enteric viruses (which can multiply in the gastrointestinal tract of humans or animals and contaminate water sources) and developed the methodology for quantifying these viruses in watershed. “So when this pandemic came, we were quickly able to be involved in these tests. I think we were one of the earliest involved labs in Canada,” says Pang.
Pang adds that there are some restrictions as wastewater testing cannot determine who is infected or the number of individuals impacted. It can’t reveal severity of illness or how the health-care system will be impacted. The data is designed to be complementary to other forms of monitoring. Pang also says that the RNA level of one sampling site can’t be compared with another as the characteristics of each area and treatment plant are different — instead, the data should be looked at in terms of long-term trends.
Not all of the data is shared publicly. It’s also used to monitor outbreaks at specific sites, which is especially vital to vulnerable populations at long-term care facilities. The teams share that information with the sites three times a week.
The labs also have the ability to detect the specific variant in the wastewater samples. Pang’s team knew when Omicron started in different communities and the speed at which it spread.
Lee says: “So, that is another way of using wastewater monitoring and to look at the emergence of new viruses. And that is actually a national collaborative or even international collaborative work, because, when South Africa identified the variant, they reported it to World Health Organization. And we got the sequence out and people across Canada worked together to develop, hopefully, the best method to detect it. This is a very rapidly changing field. If we have another variant of concern, those steps will happen again.”
This article appears in the May 2022 issue of Edify