With an estimated 50,000 visitors in Milwaukee this week for the RNC, Sandra McLellan – a professor at UWM’s School of Freshwater Sciences – and her team are looking at the bacterial changes in wastewater due to the influx of people. It’s a continuation of their work with the Wisconsin State Lab of Hygiene, which is examining a variety of issues, including COVID, influenza and other bacterial changes in Milwaukee wastewater. Milwaukee Magazine spoke with McLellan about the project and their work during the RNC.
What is the Wastewater Surveillance Program?
We have this global pandemic, and wastewater surveillance became a really effective way to monitor the community. Early on, my lab partnered with the State Laboratory of Hygiene in Madison. Along with our Department of Health Services, over the last four years we have built a Wastewater Surveillance Program. [The Department of Health Services] really did the heavy lifting around the state, and we’ve been monitoring Southeast Wisconsin, including Milwaukee, and the City of Milwaukee Health Department is a partner in that also. They’ve kind of taken over sampling Milwaukee and kind of the routine basis for COVID.
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Tell us a little bit about what your team will be doing during the RNC.
While there’s large gatherings, of course, there’s going to be concern for infectious disease. So for the RNC, the Department of Health Services, along with the city of Milwaukee, was talking about their overall surveillance plan for health, and wastewater surveillance was a natural component of that. What we are doing for it is pretty much more intensive sampling for COVID, RSV and influenza. There are also a lot of enteric viruses – just because they go around in summer – some of them are food-borne illnesses or person-to-person. We’re really looking at all of these targets on a daily basis. We started [sampling] a good week before the convention started and we’ll be working daily to pick up samples from the sewage district, we do our respective testing and all the results get turned around by the next day. We’ll do that throughout the convention, and then we’ll follow up for at least 10 days, or almost two weeks, after on a daily basis.
How are you able to see if there are respiratory illnesses in the water?
A lot of respiratory pathogens, and enteric pathogens, are shed in feces or through saliva. When people brush their teeth or tissues get flushed down the toilet, all of that makes their way into the sewage system. We can actually take the untreated sewage and extract DNA and RNA from it. Because it’s a large system that all comes together in one location in Milwaukee, there’s the Jones Island Wastewater Treatment Plant and the South Shore Wastewater Treatment Plant which is an integrated sample of almost 400,000 people for Jones Islands, and 600,000 for South Shore. That’s how we can get an idea of what’s in the community, if it’s increasing and the baseline of what was there before the convention and what might show up.
What does the actual testing look like?
The wastewater treatment plant actually collects the samples for us, because they do that on a daily basis anyways. Any wastewater coming into the plant is systematically sampled throughout 24 hours. We’ll get a 24 hour sample that really represents the last 24 hours, and it’s from there that sample comes into our laboratory and we use a lot of specialized reagents to actually extract the RNA and DNA. Once we have that, it’s exactly like what happens in a clinical laboratory for testing for COVID, or any infectious disease, we’re amplifying the DNA that’s very specific for that virus, quantify it and then we report those results.
When did you begin planning for the RNC?
Very, very early on, like six months, if not longer. We’ve been working with our counterparts in Chicago, because they’re going to be doing the same thing for the Democratic National Convention. Now [wastewater surveillance] has been going on in so many cities for the last several years, but there hasn’t been a lot of experience on monitoring large gatherings. I think we’re going to learn a lot about what we can expect when this many people get together and just gain experience over time.
Do you have a prediction of what the results will show?
It is too hard to tell early on. Especially since we don’t know if there’s a lot of people coming into the city with COVID, if there is, we might see more COVID spreading around the city after; but, if there’s just some baseline COVID here, it’ll stay the same. Although at the convention it’s really hard to say whether people could actually have closer contact than what you would expect in everyday life, since it’s a bit open space. It is just really, really hard to predict.
