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University of Minnesota researchers are testing residence hall sewage for COVID-19 on the Twin Cities and Duluth campuses in hopes of catching cases early and preventing outbreaks among students.

The U is among a growing number of colleges nationwide experimenting with sewage testing as a public health tool that could help keep campuses open through fall semester. The University of Arizona and Utah State University recently quarantined and tested hundreds of students after dorm wastewater samples led to the discovery of undetected COVID-19 cases.

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The technology, as shown in a dorm case on the Arizona campus in August, could establish wastewater epidemiology as a leading indicator for disease outbreaks, even when those affected are asymptomatic.

“A lot of priority has been placed on this,” said Richard Melvin, assistant professor at the University of Minnesota Medical School in Duluth, who is working with assistant professor Glenn Simmons Jr. to lead the research. “We feel pretty confident that we are going to get a good picture of what’s going on in the dorms this way.”

Wastewater epidemiology is still in the early stages at the U, having started only last week.

In a separate experiment that began last spring, U researchers are also testing water in dozens of municipal wastewater treatment plants around the state and sending the data to the Minnesota Department of Health to analyze.

“We’re at a spot in this pandemic where there is no one thing that is going to save us, and I feel like we should be trying various things that can add on to all of our collective understanding,” said Sara Vetter, interim assistant division director of the state public health lab. “I am interested enough in it that I want to see where it’s going to go at this point.”

The Health Department on Sunday reported a single-day high of 1,318 new cases of COVID-19, bringing the state’s total number of lab-confirmed cases of the viral respiratory illness to 90,017. In Minnesota, 1,965 people have died from the disease, including two deaths reported Sunday. One of those cases involved a person living in a long-term care or assisted-living facility.

At the U, the school’s online COVID-19 dashboard shows 19 of 210 students tested positive at the Twin Cities Boynton Health clinic between Sept. 11 and 17.

Plumbing for virus

The idea for testing wastewater for genetic material from the virus that causes COVID-19 is based on the fact that humans “shed” the virus in their stool, as well as in breath droplets and nasal secretions. The same technology that can diagnose the virus in a nasal swab can be used to detect it in a sample of wastewater drawn from the outflow pipe of a college dorm.

Research shows that the virus may remain in stool much longer than in samples from nasal passages.

A study of 96 consecutive COVID-19 patients from a hospital in the Zhejiang Province of China from January to March found the virus detectable in fecal matter for a median of 22 days after onset, versus 18 days for respiratory samples, according to a report in the BMJ.

The virus was equally detectable in stool regardless of whether the patient had mild or severe symptoms.

An April article in Nature about a pioneering Dutch wastewater surveillance program for COVID-19 said the virus can appear in feces within three days of infection.

But the median time to develop symptoms of COVID-19 is five days after transmission, and the median time when people need to be hospitalized for it is seven days from symptom onset, according to a February article on Chinese patients in JAMA.

Researchers from Yale University monitored wastewater from March through May in New Haven, Conn., and concluded in a preprint study that increases in concentrations of genetic traces of the virus in a sewershed of 200,000 people preceded a rise in local hospital admissions by three days, and an increase in overall COVID-19 case counts by seven days.

Results may vary in other communities, the authors noted.

Wastewater content varies widely because of differences in diet, mineral content, and chemicals contributed by industry. And though states, cities and universities are monitoring wastewater for COVID, they’re not following industry standards — because there are none yet.

“It’s still very much in the research mode,” said John Albert, chief research officer for Denver-based Water Research Foundation, which held a summit on COVID-19 wastewater surveillance in April.

Still, wastewater monitoring has already been used for public health programs.

In 2013, scientists detected a “silent” outbreak of wild poliovirus in sewage from Rahat and Beer Sheva in southern Israel. In January, Massachusetts-based Biobot Analytics published a report showing a robot could detect opioids in wastewater to help guide treatment and harm-reduction programs.

“This approach of looking at wastewater for signs of what’s to come could be useful at a municipal level, at the state level, and very much useful at a granular level — hotels, dorms, nursing homes. You may even think about cruise ships,” said Sameer Moorji, director of applied markets at Madison-based Promega Corp., which sells reagents and equipment for wastewater surveillance.

Testing at the U

At the U, researchers are collecting and testing sewage samples twice per week from 13 sites on the Twin Cities campus and six Duluth dorms throughout the fall semester.

They’ve placed automated sampling machines at dorm wastewater outlets to collect specimens for 24 hours.

“Whenever the flow has an uptick, the machine starts sampling the wastewater,” Melvin said.

Samples are taken on Tuesdays and Thursdays and tested on Wednesdays and Fridays in a dedicated laboratory on the Duluth campus.

Researchers will be able to track changes in concentrations of viral material over time, with higher concentrations potentially indicating increased numbers of cases in the dorm.

The U currently views the work as “academic research,” but will monitor early results for potential application, said Jill DeBoer, director of the university’s Health Emergency Response Office.

Wastewater testing could give the U a broader look at COVID-19 transmission on campus. The school is currently only testing students who are symptomatic or have been exposed to someone infected, and it is not asking students to self-report if they have tested positive off campus.

Gathering data on people who have not, or cannot, get a COVID-19 test is one of the key reasons why wastewater epidemiology is being pursued, on campus and in the broader community.

“We always knew there was going to be an issue with individual testing,” Simmons said. “It’s really been a major issue that a very large population of individuals have not been tested, just because they have so many barriers to getting tested.”

Joe Carlson • 612-673-4779

Ryan Faircloth • 612-673-4234