Every Thursday, a researcher from Yale University picks up a cooler from the East Shore Water Pollution Abatement Facility in New Haven.
In that cooler is a week’s worth of samples from the sewer system that experts call “sludge,” or the solid waste that is left over after treating wastewater. It can contain a mixture of chemicals, metals and remnants of human waste that is flushed down the toilet.
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“In that waste, you can tell not just what diseases those people have, but you can sometimes tell what they eat, you can tell what kind of drugs they take, and you might be able to tell something about their metabolism,” said Jordan Peccia, Yale professor of environmental engineering.
Peccia is leading a team of engineers, epidemiologists, public health experts, medical students and business professionals in an ongoing study that monitors the presence of the novel coronavirus in municipal sewer sludge in order to track when COVID-19 infection is spreading or slowing down within a community.
Early study results published in a working paper last month show that this method of disease surveillance detected changes in community outbreak up to seven days before those changes showed up in COVID-19 swab testing data, which can have a slower turnaround and be inconsistent.
Scientists said this could be a more accurate, independent tool for city leaders and public health experts in predicting a resurgence of viral outbreak.
“If we can see a little bit into the future, we should be actively involved in trying to figure out if it’s going to go back up again,” Peccia said.
Yale researchers are working on the study in partnership with the Connecticut Agricultural Experiment Station.
The team’s first published set of results analyzed sludge samples taken from the New Haven wastewater treatment facility, which serves about 200,000 people, from March 19 to May 1. Researchers compared their findings to local COVID-19 hospital admissions and positive cases.
The sludge samples, which contain SARS-CoV-2 viral RNA, or genetic material, are brought to a Yale lab where scientists purify the RNA. The samples are then sent to the experiment station, which runs them through testing.
Results are sent back to Yale researchers who compile a report for New Haven city officials.
Other institutions and individual water utilities throughout the United States and around the world have launched coronavirus wastewater surveillance programs or used existing programs already designed to detect and monitor diseases like polio, typhoid and other viruses.
Rolf Halden, a professor and director of the Center for Environmental Health Engineering at Arizona State University, said “wastewater epidemiology” has largely been an underutilized tool in the United States.
“We call the sewers the information superhighway where barely anyone plugs in, because there’s so much information in there. Yes, it’s not attractive, but it sure delivers,” Halden said during a recent webcast hosted by the Earth Institute at Columbia University.
“And the doctor uses, draws on the same resources -- urine, stool -- to give you your personal health information, so why wouldn’t we do it for a city?”
Researchers and engineers at Arizona State University’s Biodesign Institute have been conducting a coronavirus wastewater surveillance program in Tempe, a city just east of Phoenix. They used technology they had already implemented to track opioid abuse in the city’s population.
Halden said the surveillance isn’t perfect, and that it does have weaknesses, but he’s optimistic that it can provide important insight for cities and communities.
Krista Wigginton, an associate professor of environmental engineering at the University of Michigan, is involved in coronavirus research that is sampling from almost 50 wastewater treatment plants across the country. She spoke as a panelist during an annual meeting of the Water Science and Technology Board at the National Academies of Sciences.
Wigginton said data from testing wastewater can be used in several ways, like to confirm that an eradicated disease continues to stay absent from a specific place or area, or to monitor for trends in a persisting disease outbreak.
“The thing that everybody wants, but is going to be the hardest, is to actually convert the numbers that you’re measuring at the wastewater treatment plant or in the sewage line to an actual prevalence number,” she said. “Can you get to a concentration measurement and then say, this is how many people in the building or this is how many people in the community have the illness? We have quite a bit of work to do until that’s a possibility.”
Peccia said while wastewater disease surveillance could be useful in other major cities, it could also benefit rural areas, too, where regular and frequent COVID-19 diagnostic testing may be unpredictable.
Going forward, Peccia said his team at Yale will look for more funding to increase the frequency of their testing and expand it to more cities.