DAVID GREENE, HOST:
So if you're about to take a bite of cereal, maybe don't do that while you're listening to this next story because we're about to take you into the sewers. This is because traces of the coronavirus in humans can be found in poop. What college students send down those pipes in their dorm, it's helping campuses catch outbreaks of coronavirus early. NPR's Elissa Nadworny braved the sewers.
ELISSA NADWORNY, BYLINE: Before we head underground, we've got to get suited up. Because we'll be sampling wastewater, potentially full of nasty microbes and possibly the virus that causes COVID-19, we're wearing masks, face shields, gloves and safety suits with booties.
UNIDENTIFIED PERSON: Whoo (ph). It's a long leg (laughter).
NADWORNY: Our destination is under South Hall, a mostly freshman dorm on the campus of Colorado College, a small liberal arts school in Colorado Springs. Andrea Bruder, a math professor, is leading our journey. Wastewater and poop - they're new to her team.
ANDREA BRUDER: In normal life, we work on a project studying a predator-prey system of ladybugs and aphids.
NADWORNY: She's now turned her attention to wastewater because the virus shows up in poop before an infected person has symptoms and even if they never get symptoms.
BRUDER: You can see one of the access points to the building right here and...
NADWORNY: Bruder points to a little door on the side of the brick building with a ladder leading down to a tunnel. We follow Bruder down the ladder.
BRUDER: And you just sort of step over those pipes right there.
NADWORNY: Our mission is to collect enough wastewater from those pipes to search it for traces of the virus. It's pretty dark, but surprisingly, it doesn't smell. Because the tunnel is too small for us to stand, we squat-walk about 15 feet. All the water expelled from the dorm above - from the shower, from the sink and, of course, from the toilet - travels down here. We hover over an access point in a thick metal pipe.
BRUDER: Step one - we remove the lid.
NADWORNY: Bruder gets out a plastic ladle and a to-go coffee cup, ready to collect.
BRUDER: And it looks like we just have a little bit of flow.
NADWORNY: She just needs enough flow in the pipes to get a good sample.
BRUDER: No very much. So we have to wait a little bit.
NADWORNY: And then you just pray that someone goes to the bathroom?
BRUDER: And then I just wait and listen for somebody to flush, yeah. Yeah (laughter).
NADWORNY: This underground adventure - or versions of it - is becoming increasingly popular on campuses. According to analysis by NPR, more than 65 college campuses are using wastewater to help limit the spread of the coronavirus. And that number is growing. We'll come back to Bruder, waiting in those dark tunnels at Colorado College, in a minute. But to see what they're trying to accomplish down there, we have to go to another campus - four hours north to Colorado State University in Fort Collins.
CAROL WILUSZ: At this point, now - even if we do get shut down - I know that we've delayed a shutdown, and our university's been able to stay open longer because of what we were doing.
NADWORNY: Carol Wilusz is a microbiologist at CSU and leads the lab on campus where wastewater samples get processed.
WILUSZ: That's a lot of relief that it all works.
NADWORNY: If Wilusz and her team find elevated levels of the virus in the wastewater coming from a dorm, they quarantine the students living there and give them nasal swab tests to see who has the virus. The last time there was a spike, follow-up testing found nine positive cases. For Wilusz, there is one dorm that's of special interest to her - the one where her son, a freshman at CSU, has been living.
WILUSZ: (Laughter) So I'm keeping an eye on that one.
NADWORNY: The operation at CSU has been going on all semester, and it's far more robust than the one at Colorado College. We caught up with the team collecting the samples at a manhole cover in a parking lot.
ABBIE MODAFFERI: We have it down to a science at this point (laughter).
NADWORNY: Abbie Modafferi is one of the grad students working to gather the samples.
MODAFFERI: Next, we're going to a location that receives wastewater from one dorm in particular.
NADWORNY: There are 17 sites they sample across campus.
MODAFFERI: A lot of in and out of the van all day (laughter).
NADWORNY: We catch a ride to the next location - Westfall Hall, a 12-story dorm with Modafferi's supervisor, environmental engineering professor Susan De Long.
SUSAN DE LONG: All of the locations that we sample as a part of this project are associated with dorms or other residences.
NADWORNY: That's because people poop at home. De Long says dorms are ideal because you know who lives inside, and that helps narrow down who might be infected.
MODAFFERI: It's not the most glamorous way to sample, anyway, but...
NADWORNY: Unlike the folks at Colorado College, there's no need to crawl underground here. They simply pry open the manhole cover, exposing a pump that does the dirty work for them, collecting wastewater every 15 minutes for a 24-hour period.
So you could catch someone who went to the bathroom in the morning and who went to the bathroom in the evening.
DE LONG: Yeah. And somebody who slept in till noon and then went to the bathroom. We can't just assume that everybody's going to the bathroom at 7:30.
NADWORNY: The wastewater testing can't tell CSU or any campus who is infected with the coronavirus. And because people shed different amounts of the virus at different times, there's no way to know how many students might have it. Instead, the data is used to show trends and dictate follow-up testing.
(SOUNDBITE OF WATER SPLASHING)
NADWORNY: Abbie Modafferi pours the yellowish liquid from the pump into test tubes. I ask her how it smells.
MODAFFERI: Some days are worse than others. That doesn't bother me, though (laughter).
(SOUNDBITE OF WATER SPLASHING)
NADWORNY: She's not grossed out by poop. She's changed her fair share of diapers babysitting. Plus, she's helping CSU keep the campus open.
MODAFFERI: If we're really trying to slow the pandemic, the biggest thing we could do is prevention, and this is how you do that.
NADWORNY: Back in those dank tunnels at Colorado College...
BRUDER: Still quiet - no flushing.
NADWORNY: ...Mathematician Andrea Bruder is still waiting patiently for enough water to run through the pipes.
BRUDER: We don't need a lot, but we do want to be able to fill three sample tubes.
NADWORNY: We're down there in the dark, squeezed up against the pipes, sweating profusely, for what feels like forever.
BRUDER: Waiting for the flush.
NADWORNY: After about 20 minutes, we finally hear a very welcome and familiar sound.
(SOUNDBITE OF TOILET FLUSHING)
BRUDER: OK, so we heard the flush, and now it takes a little while to get here. And here's some TP.
NADWORNY: Bruder ladles the freshly flushed liquid with fragments of toilet paper into her cup.
BRUDER: We've got a good sample.
NADWORNY: We won't find out until later that that sample did not contain traces of the coronavirus. Bruder says testing wastewater, it offers her campus and many others one bit of hope, courtesy of No. 2.
Elissa Nadworny, NPR News, Colorado Springs, Colo.
(SOUNDBITE OF LYNYRD SKYNYRD SONG, "THAT SMELL")
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