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UVa searches sewers for signs of shed virus

Every 15 minutes for 24 hours, little robots named after “Star Wars” characters dip their tubes and drink deep of the discharge flowing out of pipes from dormitories and other buildings at the University of Virginia.

The devices take samples of sewage that will be frozen, spun and analyzed for signs of viral ribonucleic acid residues that could give advance warning of the SARS-CoV-2 virus and a possible outbreak of COVID-19.

“The virus’ RNA is shed in stool very early in an infection, with some data showing that it’s shed even before you’re actively infected with the virus,” said Dr. Amy Mathers, a pathologist and associate director of clinical microbiology at UVa Health. “What we’re hoping to do with the robots is capture that stool to test for the RNA. With a 24-hour sampling regimen, we can get a good snapshot of everyone who has been in that building that day.”

The robots — Chewbacca, Anakin, C-3PO, R2-D2 and Obi Wan — and the stool samples they snag are all part of UVa’s plan to get a heads up on potential COVID-19 outbreaks on Grounds.

In the effort to control the virus, the wastewater tests are used in conjunction with COVID-19 testing regimens among students and contact tracing.

“There’s a synergy there. We’ve had incidents where there were new cases that had presented symptoms and we decided we needed to test everybody in that building, and the wastewater tests showed it was, indeed, in the population,” Mathers said. “We’ve also found RNA in wastewater samples of a building that no one had yet tested positive in and there were no outbreaks. We were able to go in and test people before an outbreak occurred and found some positive test results.”

The presence of virus RNA in wastewater is not necessarily an indication of student misbehavior, Mathers said.

“Residence halls are a likely place for an outbreak because these are living quarters. They are where people eat and sleep and live, and you can’t wear a mask 24 hours a day,” she said. “The Department of Corrections, meat packing plants, nursing homes — anywhere that people are in close proximity can lead to an outbreak. Wastewater monitoring can give us advance notice of the virus and we can get ahead of it.”

Digging through a day’s worth of excretions on the way to a treatment plant may not be as glamorous as the white coat-clad researcher staring deeply into a test tube, but it works.

“Several studies have demonstrated that increases in SARS-CoV-2 RNA can be detected in environmental samples several days before detection of COVID-19 through clinical surveillance,” an Aug. 7 status brief on the topic from the World Health Organization states.

“There is potential to use environmental surveillance for early warning, particularly of clusters or outbreaks in countries that have already contained transmission and are easing public health and social measures, or in the event of seasonality,” the report states.

Monitoring wastewater to track viruses is not new. It’s been used in the past to track down polio and other viruses around the world. In some countries, including Russia, wastewater is monitored regularly to watch for the return of polio. There have been studies in several countries, including the United States, on monitoring wastewater for the presence of illegal drugs.

Although the virus sheds in mass quantities with human stool, it does not survive well in the interesting mix that is wastewater being discharged from a building into a sewage system.

“RNA is not a stable molecule, so the samples and testing all have to be done on site. We have to keep the samples really, really cold and we create a composite sample and spin it in an ultra-centrifuge and then try to identify the RNA,” Mathers explained.

“So far, no one has detected viable virus RNA in wastewater, although I’m not saying it hasn’t happened ever,” she said. “That makes me feel comfortable about the safety of the collection and testing process.”

For UVa, the process was in practice prior to the students’ return.

“We spent our summer trying to figure out how to do this,” Mathers said. “We tried grab samples. We took samples we knew should test positive and let them sit for a while. We sent it to an external lab for tests and found that they didn’t test positive at all. That convinced us of the need to do it here.”

Mathers and the sample team also worked with the Virginia Department of Health to monitor wastewater from nursing homes during outbreaks. They tested student-athlete dorms when the players returned in July, comparing their results with the regular testing of the athletes.

“We were able to validate the process,” Mathers said. “By the time the students came back to Grounds, we had ironed out the kinks.”

If the passive surveillance of sewage works for UVa, it might work for the community at large. According to WHO, the Netherlands plans to incorporate daily sewage surveillance into its national COVID-19 monitoring, and similar approaches are being considered in Germany. Australia and New Zealand already have started programs, the organization stated in its status update.

“Conceivably, you could set up monitoring at the Rivanna Water & Sewer Authority to get an idea of how prevalent the virus is in the area,” Mathers said. “That could show a surge is coming before it happens.”


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