Sewage Sampling Key To Controlling COVID-19 At UCSD
Tuesday, August 17, 2021
Photo by Matthew Bowler
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A sewage testing program at UCSD could be key to helping identify COVID-19 outbreaks when students return to school in the fall.
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The unassuming grey robots basically just sit on top of manhole covers on the UC San Diego campus.
The automated wonders are about the size of an upside-down 10-gallon bucket. Think of a small R2-D2 unit without wheels.
Researchers are using a system of these unassuming robots to monitor sewage on campus. It is a key part of a sophisticated COVID-19 monitoring system that will help officials identify and contain outbreaks this fall when the campus is full of students for the first time in more than a year.
Inside the unit, there’s a simple computer that can schedule samples throughout the day. A half-inch rubber tube on the side of the device snakes into the manhole cover then directly into a sewer line.
Under a second lid inside is a plastic water bottle that holds all of the samples taken in the past 24 hours.
Postdoctoral researcher Smruthi Karthikeyan scans a bar code on the machine and confirms which nearby building the sample is coming from.
There are more than 120 of these robots quietly doing the dirty work in the battle against the pandemic on the UCSD campus.
“It keeps taking these samples over a 24-hour period so when we pick up the sample the next day,” Karthikeyan said. “It's representative of the entire day and not just the moment we’re grabbing samples.”
Samples are collected once a day and taken to the lab inside the school’s Biological Sciences building.
“I am scanning in the bottles after they’ve been collected,” said Kaitlyn Tribblehorn, a lab assistant.
A QR code on each bottle registers where the sample came from in a Google doc.
The sewage water in the bottle is concentrated and prepared for analysis.
The system has evolved since it was first deployed last summer. And that’s important because pretty soon the campus will be crowded.
Sample collection and testing are only the beginning.
Results are put into UC San Diego’s COVID-19 daily dashboard.
The pandemic’s impact is tracked there including how many people on campus had the infection in the past week.
The sewage testing data is shared there as well, allowing anyone on campus to see where a positive test happened.
“We have an interactive map with all these buildings which get updated every day,” Karthikeyan said. “So if you see a blue that means that building did not have a base water positive. If it was red is means we did see a positive signal from wastewater that day.”
The building occupants are typically notified and encouraged to get tested if a building’s sample tests positive for the virus.
The data is updated once a day allowing people to see the history for several hundred campus buildings.
“We can see if it was one infected individual in the building infecting the other people,” Karthikeyan said. “Or they all picked up their infection somewhere else and brought it back to campus.”
Rob Knight, the director of the center for Microbiome Innovation at UCSD, helped set up the system because researchers realized early on that COVID-19 was being transmitted before people showed outward symptoms.
Sewage turned out to be an early warning system for COVID-19 infection.
“We think of COVID as infecting our lungs and our airways but it also infects our gut,” Knight said. “And for many people, it infects the gut before it infects the respiratory system. So you can be pooping COVID into the sewage long before you show up at a hospital with respiratory symptoms.”
Early testing last summer led to the discovery of infections on campus in people that didn’t realize they had the disease.
“Even if you’re vaccinated you can still get infected,” Knight said. “And you can still infect other people. And so keeping our astonishing success rate going on campus is going to require people being extremely vigilant.”
A recent peer-reviewed study by Karthikeyan and Knight found 85% of COVID-19 cases on campus were detected early by the sewage testing system.
That makes the robotic samplers a crucial tool to control outbreaks once students return to campus next month.
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