Best COVID warning system? Poop, pooled spit, CSU says

Carol Wilusz’s mornings now often start at 4 a. m., scanning the contents of undergraduates’ feces. Specifically, scanning the data on how much coronavirus they flushed into the shadows, destined to be extracted from 17 manholes connected to dorm buildings on Colorado State University’s Fort Collins campus.

“There are quite extensive numbers of poop jokes,” said Wilusz, a CSU molecular biologist.

Emerging research suggests infected people start shedding the coronavirus in their poop early in their infection, and possibly days before they begin shedding it from their mouths and noses.

“It means that we can catch them before they’re actually spreading the infection,” she said.

In normal times, Wilusz studies stem cells and muscular dystrophy. Now, her team is on the front lines of defense against the massive COVID- 19 outbreaks that, for a campus with more than 23,000 undergraduates alone, always seem to be lurking around the corner. The sewage review is part of a multipronged attack that includes the usual weapon of contact tracing plus a specialized “paired pooling” form of testing saliva samples. So far, the school has had about 500 cases since the semester started, about half that of the only somewhat bigger University of Colorado Boulder.

Amid fluctuating scientific recommendations and a virus that still holds uncertainties, colleges across the country are taking a choose-yourown- adventure approach to COVID- 19. For those holding in- person classes, the adventure includes an extra puzzle: how to concentrate a lot of people into one place without an outbreak tearing through the student body and spilling into the community, all without safety precautions that would break the bank. Testing is at the core of those plans.

“A lot of these institutions started testing just symptomatic students. And that is really not good, to put it bluntly, because as we’ve seen over the past couple of months, students tend to be asymptomatic,” said Chris Marsicano, an assistant professor at Davidson College in North Carolina who is leading an initiative tracking how universities are responding to the pandemic. “The institutions that have been the most successful are ones that are testing every student at least once a week.”

According to data collected in mid- September, only about 6% of large universities with in- person classes are routinely testing all students, according to an NPR analysis of his group’s data. The University of Illinois at Urbana- Champaign has been leading the pack, testing about 10,000 students each day using a streamlined spit- testing method. But it’s pricey. Despite driving down the cost of an individual test to about $ 10, Paul Hergenrother, a chemist leading the effort, said the school is still spending about $ 1 million a week.

At Colorado State University, Lori Lynn, co- chair of the school’s pandemic response team, said initially the school was paying $ 93 a pop to test students using the usual nose swab method.

“We quickly spent several million dollars on testing,” said Lynn, who added that cost is just one limiting factor. “We can’t test everybody in the community, you know, weekly or twice a week.”

Instead, Mark Zabel, a CSU molecular biologist and immunologist who typically studies neurodegenerative diseases, said his group recently figured out how to screen saliva for less than $ 20 a person. It involves pooling drool samples in a strategic way reminiscent of the children’s game Battleship.

Instead of pooling samples willy- nilly, Zabel and his colleagues are doing something he calls paired pooling: They start with an eight- by- eight grid of saliva from 64 people, arrayed almost like a Battleship board. Each person’s spit sample gets divided up and analyzed in two pools — one pool for the row it sits in and one for the column it sits in — for a grand total of 16 pools per grid.

If the test containing samples in Row A and the test containing samples from Column One appear positive, that would indicate that the person whose spit is in the A- 1 slot is a positive case.

“So, it’s super easy if we’ve got one positive among 64,” said Zabel. In that case, they’ve screened 64 people with just 16 tests. No retesting necessary.