Down the Pipes: How Sewage Tells Us Where COVID-19 is Spreading

Sept. 6, 2021, 10:56 a.m. ·

Teams used auto samplers to collect waste water for testing throughout five manholes in Lincoln. (Photo Courtesy of Dr. Xu Li, University of Nebraska-Lincoln)

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A new key to tracking and possibly predicting COVID-19 case outbreaks may lie below ground -- throughout sewer systems underneath cities.

Throughout the COVID 19 pandemic, many of us became more familiar with epidemiology, and the researchers who try to track and prevent virus outbreaks. Contact tracing is one way to see where the virus was and is going, but that's more after-the-fact of spreading the virus.

A newer method involves looking underground in our sewer system. When a person is positive for COVID-19, they can shed the virus through their stool. Dr. Xu Li is a professor at the University of Nebraska-Lincoln's School of Civil and Environmental Engineering. He helped run a project in 2020 that tracked COVID-19 through our wastewater.

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Photo courtesy of Dr. Xu Li, University of Nebraska-Lincoln

"I think it's the novelty of this spatial granularity that really kind of proved the usefulness of this wastewater- based surveillance methodology. And also really working with LTU partners, it was it was a great experience.

"This is a kind of a first trial. People haven't been sampling manholes for wastewater at that level of frequency. It was a lot of laborious work to load the samplers into a manhole, and it's even more laborious to pick it back up the next day when it's full. And also really working with colleagues in the nutrition and health department to look at the implication of wastewater data -- what does it mean for health intervention, developing targeted health intervention strategies. I think that's really another good point -- how to use this surveillance data and bring the surveillance data to the next level. I thought that was really, really good," Li said.

Dr. Xu Li

Dr. Li's team was able to track outbreaks and even narrow them down to zip codes within Lincoln.

"So if we monitored the barrel concentration in the wastewater representative of a single zip code, then we can see within that community during that time period, [whether there] was there a small outbreak or not."

"The result is kind of interesting. Between the sampling period from early July to early August, there was really two peaks in Lincoln. There was one at the end of July, early August, and then there's another bigger peak coming up at the end of September and kind of going beyond our sampling period. And we do see during the first COVID peak, there was a certain zip code, we saw a higher level of concentration in the wastewater but we didn't see that same phenomena in the other zip code."

"But during the second peak, it's kind of pretty universal. All the zip codes that we sampled see a surge. But there was one particular zip code having really high surge of virus concentration," Li said.

Dr. Shannon Bartelt-Hunt

Now this work is also in motion in different cities across the state. Dr. Shannon Bartelt Hunt is the chair of the Civil and Environmental Engineering Department at the Nebraska of Nebraska-Lincoln. She says this work can be pivotal once the technology is developed more.

"Some of the things that we found was that in the community-level monitoring, that monitoring COVID and wastewater was a good predictor for health data such as cases. We found that in Grand Island, especially that what we were seeing within the community, in terms of the level of the virus in wastewater was predictive, was maybe as much as like seven days ahead of time of what we might see as far as rising or falling cases within the community," Bartelt-Hunt said.

"We also found with the school-based pilot program that wastewater could be sort of an early-warning predictor that could then help direct testing resources into the school setting."

And more work is underway to connect the research to a larger part of the state and the country.

"I think you know what we're going to start doing with the Department of Health and Human Services is part of a national surveillance program that's being set up by the CDC. So we'll be contributing data from Nebraska, and I think that there's a lot of interest, even at the national level, to continue to monitor wastewater for COVID and potentially for other for other viruses, as well. It's kind of standing up a new method for public health monitoring.

The first results of this study were recently published in the journal 'Science of the Total Environment.'