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Science and Innovations

NAU Scientists Look For Clues To COVID-19 In Sewage

Northern Arizona University

Researchers at Northern Arizona University have been keeping a close eye on sewage for clues to the spread of COVID-19. They say wastewater monitoring can be a powerful tool for altering authorities to possible coronavirus outbreaks, especially in crowded living conditions like university dorms. KNAU’s Melissa Sevigny spoke with NAU’s Dr. Crystal Hepp about how the research is part of a “search and destroy” strategy to help university administrators focus coronavirus testing where it’s needed the most.

Where have you been sampling wastewater and what can it tell you about COVID-19?

Since the beginning of March we’ve been sampling wastewater across different parts of Northern Arizona, including Flagstaff, Munds Park, Kachina Village, Sedona and the Village of Oak Creek. But more recently starting at the end of July we started also sampling at Northern Arizona University to try to better understand how we might be able to inform mitigation strategies.

How can this inform mitigation strategies?

So looking at congregate living locations, and just smaller locations, can really help identify different parts of the population that maybe we should be looking at more for potential asymptomatic cases that could spark a larger outbreak… How it works is that we sample several times a week, and then after we run our tests at the Pathogen and Microbiome Institute, we then provide our information to NAU administration. Based on our results, as well as several other metrics that they’re taking into consideration, they can then decide who’s going to be part of the mitigation testing, so part of that is going to be a random population, but other things are feeding into that determination, including wastewater testing.

Can you walk me through the process of how you take a sample and where it goes from there?

I’ll start with the wastewater treatment plants. Most of them are technologically savvy and they have composite samplers built in. What a composite sampler is, or what it does, is it takes a sample of the untreated sewage, the influent, every half an hour for 24 hours, and then from that composite sample that’s supposed to be a composite sample of the entire community for one day, then we take a sample of that…. However at the dormitories… we’ve had to alter our methodology. That’s because, in particular at Northern Arizona University, we only have two composite samplers….They’re pretty expensive, they can be up to $5,000 apiece. We didn’t want to purchase a ton of them either…. So instead what I did is I went out and bought some tampons…. and we were tying a string to those and we will put those into the manifolds for 48 hours. Then we pulled the sample and it’s working really well.

When the pandemic started did you know you were going to be spending this much time looking at wastewater samples?

I didn’t. That was a big surprise to me…. Nobody in our lab really enjoys taking sewage samples or handling them in the research laboratory, for that matter, but the fact that we know that we’re making a difference here in Flagstaff is really important to us.

How long do you plan to continue this research?

We’re hoping that we are going to be doing it at least through the end of the pandemic… but we are writing other grants to continue this carrying out this type of research for other viruses, bacteria, antimicrobial resistance… We actually have already ordered in reagents to start, at the same time we’re going to be looking for SARS CoV2, we want to be looking for influenza A and B… but we also want to look for norovirus, other enteroviruses, things that make people really sick that come around every year where we feel if we just said, “hey, this is here, and you wash can your hands and perhaps prevent yourself from getting it,” we think that would be a big service to the community.

Crystal Hepp, thanks so much for speaking with me.

Thank you.

Melissa joined KNAU's team in 2015 to report on science, health, and the environment. Her work has appeared nationally on NPR and been featured on Science Friday. She grew up in Tucson, Arizona, where she fell in love with the ecology and geology of the Sonoran desert.
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