Twice a week, mathematics professor Andrea Bruder squats in the sewage tunnels below South Hall, a mostly freshman dorm at Colorado College. She wears head-to-toe protective gear and holds a plastic ladle in one hand and a to-go coffee cup in the other. Bruder hovers above an opening in a large metal pipe and patiently waits for a student to flush.
That flush will flood the pipes with just enough water to carry human waste down to her ladle, then to her coffee cup and eventually to a lab for processing.
According to an analysis by NPR, Bruder's small private college in Colorado Springs is one of more than 65 U.S. colleges testing wastewater in an effort to monitor coronavirus spread. And that number is growing.
People who have been infected with SARS-CoV-2, which causes COVID-19, shed virus particles through their feces when they go to the bathroom. Wastewater monitoring provides an early opportunity to catch the virus because it can detect an infection days before respiratory symptoms show up, and even if they never show up at all in the case of asymptomatic individuals.
Across the country, campus outbreaks have shut down in-person classes, led to campus lockdowns, and in some cases sent students home. Communal living and socializing has been a boon to the highly contagious virus, with much of the spread happening in dorms and off-campus housing.
Dorm wastewater offers an ideal testing scenario for colleges: People often poop where they live; researchers know exactly who lives in each dorm, which narrows down who could be infected; and testing wastewater is cheaper than regularly testing students, even when followed up by more targeting screening.
In August, the University of Arizona made news for using wastewater testing to help prevent an outbreak. Wastewater testing alerted administrators to the presence of the coronavirus in a dorm, and follow-up testing found two asymptomatic students. This method has also helped identify positive cases at the University of Virginia, the Rochester Institute of Technology and Colorado State University, which has been running a robust wastewater testing program since the start of the fall semester.
On the CSU campus in Fort Collins, environmental engineering professor Susan De Long stands next to a manhole cover nestled in the landscaping outside Westfall Hall. The dorm is one of 17 sites being tested three times a week across campus.
Students bike and skateboard by as two graduate students — dressed in white protective suits, gloves, masks and hard hats — pry open the manhole cover, exposing the sewer system below.
Unlike Andrea Bruder, De Long and her team don't have to crawl underground and wait for a flush to collect samples. Instead, there's a pump that does the dirty work for them, collecting wastewater every 15 minutes over a 24-hour period.
Taking samples over 24 hours allows researchers to catch students who go to the bathroom in the morning and those who go after dinner. "We can't just assume that everybody is going to the bathroom at 7:30 a.m. or 6:30 p.m., because [students] have different schedules in college," says De Long, who previously studied pharmaceuticals in wastewater.
When it's time for the graduate students to fill up their test tubes, they simply lift a big gray tub and pour out a bit of the yellowish fluid.
Abbie Modafferi, one of the graduate students collecting samples, says she avoids smelling the liquid (some samples, she says, are worse than others). But she's happy to be contributing right now. "I feel like if we're really trying to slow the pandemic and help get back to normal, the biggest thing is prevention. And this is how you do that."
Once the samples are pulled from the sewers, they travel across campus to a microbiology lab, where they're processed. Some colleges outsource this step, but CSU has the space and lab machines to run the analysis in-house.
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 during the course of the infection, there's no way to know how many students might have it.
"We don't know if it's 10 people with a little virus or one person with a lot," says microbiologist Carol Wilusz, who runs the CSU lab.
Instead, the data is used to show trends.
"We're constantly adjusting our testing protocol based on what the wastewater data is telling us about where we might find the next outbreak beginning," explains De Long. "When we see a spike at that dorm, we can quickly roll out clinical tests of those students, identify individuals that are infected, and move them to quarantine locations so we can stop the outbreak from becoming larger rapidly. It's allowed us to stay open, with classes face-to-face."
Traces of the virus tend to linger in human waste after a person is no longer contagious. CSU makes note of students who have previously tested positive, so when they move back into the dorms, after their isolation, researchers can account for any increased levels connected to their return.
According to Wilusz, CSU's efforts seem to be working: When they've identified elevated levels of the virus in wastewater, follow-up testing has found positive cases.
"I never really believed it was going to work this well," she says. But she's grateful it has — not just for her own research, but because her son is a freshman this fall, living in the dorms. "I have an ulterior motive," she says, laughing. "I'm keeping an eye on that one."
Wilusz estimates it costs CSU about $25,000 a month to process and analyze the wastewater samples. "It's a lot cheaper than doing individual clinical tests," she says, "but it's not a cheap undertaking."
Testing wastewater for SARS-CoV-2 is an emerging field. Often colleges are figuring it out on their own, leaning on city utilities or nearby campuses that have their own testing programs. And this type of testing has limitations. For it to be most effective, researchers would ideally be able to take samples from each individual dorm, rather than a cluster, to minimize the number of follow-up tests. But campus sewer systems don't always make that easy. And a robust on-campus monitoring system only goes so far — many colleges that opened in person saw the virus spread through off-campus parties and housing, away from the dorms that were being monitored.
That's why Andrea Bruder is optimistic about the program she's piloting at Colorado College, where most students live on campus. She and her team are still working out the best testing sites, visiting noisy facilities rooms in search of the perfect sewage pipe.
In her 11 years on campus, Bruder had no reason to know about the dorm sewage lines — much of her research focused on ladybugs and aphids on yucca plants. But like so many faculty and staff members at U.S. colleges, she's redirected her research to focus on COVID-19, using her expertise to keep the campus safe.
With just two testing sites, the operation is still small, and the college hasn't yet invested in a 24-hour pump, like CSU has. That means Bruder has to fetch the samples herself — and spend her evenings crawling into dark, damp tunnels, waiting for a flush.
It's still unclear whether testing dorm sewage, followed by focused clinical testing, will work as well as widespread testing of all students. Experts say it's a tool, to be used with many other tools, including random clinical testing, hand-washing, mask wearing and social distancing.
For now, it's offering some college communities a drop of hope, courtesy of No. 2.
NPR's Lauren Migaki contributed to this report.
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") Transcript provided by NPR, Copyright NPR.