Throughout the pandemic, many people have been keeping a watchful eye on COVID-19 numbers – in particular, how many positive tests are coming back each day.
But the not-so-fun nasal swab isn’t the only way to track coronavirus in a community. For the past year, a University of Illinois Chicago lab and its partners have been tracking the virus that causes coronavirus in wastewater and sharing the data with local public health agencies.
“They implement mitigation strategies based on patterns that we see, or they tell us where they think we should sample,” said Rachel Poretsky, associate professor of biological sciences at UIC. The data shows where hot spots are developing, when infections are rising or falling, and allows public health officials to respond quickly.
The water samples come from around the Chicago area, including sewers, congregate living settings, O’Hare Airport, and from several Metropolitan Water Reclamation District facilities. MWRD, the agency that manages much of Cook County’s waste and stormwater, was an early partner in providing water samples to UIC.
“COVID-19 is detectable in human waste several days prior to symptoms,” said MWRD Commissioner Kimberly du Buclet. “When we are processing wastewater, if we can identify pockets where the virus is forming, we can do our part in helping to end this pandemic.”
It’s a complicated process – Poretsky describes wastewater as “a really complicated matrix and SARS-CoV-2 is only one tiny thing in this whole mish mosh of lots of stuff.” But testing wastewater has the advantage of picking up on infections even if people don’t know they’re sick or haven’t been tested.
“Each (method) has its limitations on its own, but together they help give a complete story,” Poretsky said.
The effort dates back to May 2020, when Poretsky and her colleagues started assembling their team. Supply chain delays made it challenging to get all the equipment they needed, and it took time to develop an accurate method – but they were far from alone.
“People were doing this at the same time all over the country, and all over the world, in fact. We have a Slack group of thousands of people from across the world … we would share our method development and troubleshoot.”
Once the lab was up and running, regular testing began in earnest about a year ago, with water samples coming twice a week. The lab is based at UIC, and in addition to MWRD works with Argonne National Laboratory, the Discovery Partners Institute within the University of Illinois system, and the Chicago and Illinois Departments of Public Health. At the moment most of the water testing is focused on the Chicago area, but the lab is ramping up to track samples statewide and expects to cover at least one site from each of Illinois’ 102 counties by the new year.
Once COVID-19 is no longer as significant of a threat, the water testing process can be used to look for everything from viruses like influenza to bacteria like salmonella. The lab is also starting a pilot program with MWRD to test for opioid metabolites.
“Residents … should not be flushing prescription medicines down the toilet, because we cannot filter and clean those out … if they find that in our wastewater, it can certainly end up back in our freshwater supply,” said du Buclet, who stressed that MWRD wants to keep working with other agencies and labs like the one at UIC on public health issues.
“The idea of putting this infrastructure in place and investing all this research right now is that we’ll have something ready should we want to look for anything in the future,” Poretsky said.