SASKATOON

How a 'sewage crystal ball' can predict Saskatoon’s COVID-19 future

Published Saturday, November 21, 2020 9:44AM CST

The University of Saskatchewan wastewater surveillance team is predicting an in COVID-19 cases in Saskatoon based on wastewater samples. (Shutterstock/CNN)

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SASKATOON -- The University of Saskatchewan wastewater surveillance team is predicting an exponential increase in COVID-19 cases in Saskatoon in the next few days. CTV News at Five host Jeremy Dodge spoke with U of S toxicologist Markus Brinkmann to learn more. This interview has been edited for length and clarity.

I'm joined now by Dr. Marcus Brinkman, the University of Saskatchewan toxicologist who has done some very interesting COVID-19 related research. Dr. Brinkman, good afternoon.

Good afternoon. Thank you for having me.

Well, thank you for coming on. This is this is a very interesting study that you have been doing about the virus that has encompassed all our lives as of late. Just start off by telling us about what exactly this project entails. The U of S wastewater surveillance team, what have you been up to?

Yeah. So basically, we go to the wastewater treatment plant in Saskatoon here and obtain samples with the assistance of the city and look at traces of the virus in the wastewater. And that can give us a really good picture about population level trends of the virus in our community.

Okay, so basically, you're scooping up raw sewage? What are the samples exactly that you're looking at?

We're looking at what's called primary effluence. So all the materials in our raw sewage would have been removed by that time, but it's still pretty much untreated wastewater there, yes.

You're finding remnants of COVID- 19. Is it the DNA of the virus? Or what is it exactly that you're detecting here?

So this virus is a single stranded RNA virus. So what we detect is RNA very similar to DNA. And we can take those samples back to the lab and analyze those traces and quantify them. It's very similar at that point, once it's purified from the wastewater, to the test that would also be conducted on our throat or nasal swab samples.

That's interesting. What else do you detect in these samples? Are all illnesses and viruses detectable in these samples?

This idea is not brand new, we have basically adapted it to COVID- 19. It has been adapted for flu viruses and other viruses before. So wastewater based epidemiology has been around for a while now.

Okay, so how specific can we get? What exactly are you finding? Is it just the prevalence of COVID-19 in our community, or can you narrow it down in any way?

So, in our opinion, the most important part about this research is that we can detect trends of those traces in the wastewater. So when we started this in the summer we had very low values. And then at some point in October, I think on Oct. 7, was the first day when we saw increases in that signal in the wastewater. And at that time, we were puzzled by those findings, because we did not see increases in cases yet.

But a week following that, it started to pick up in the community as well. And ever since we've been leading those predictions by about a week.

Okay, that's interesting, because most of the data we get, you know, someone may have symptoms, then two days later, they go get tested, three days later they get their test results, it's all stuff that has already happened. But this is something that's actually predictive, you can almost tell the future and where this is going. That seems important to me.

I agree. So we can pick up patients before they start showing symptoms, or even asymptomatic patients that will not show symptoms at all. So we get a better picture of community level transmission compared to the more traditional ways of testing. So in a way, we provide an additional way of evidence, and it has been termed by some as a sewage crystal ball to look into the future.

That's good! Now, is there any way to take this - and I mean, I'm sure it would be amuch larger undertaking - but tailor it to different areas, so you can see where outbreaks may happen?

Yes, you could take this a bit further upstream of the wastewater treatment plant, you could look at individual neighborhoods, you run into other questions there when it comes to ethics. But similar approaches have been used at the neighborhood level, or for example, in the United States, in universities to test individual dorms, for example.

So now that we're getting this and it seems to be telling the story ahead of time, what is the next step? What can we do with this and where can we take this?

So one thing we would like to do is to take this to a broader level. Not only test Saskatoon wastewater, but other bigger municipalities across Saskatchewan. And at this point, we really look forward to continuing this sort of research and try to provide this kind of advanced notice for people of Saskatoon. At the same time we can detect when the trends go down. So if we see that public health measures are effective, we would also be able to detect that potentially.