Swabbing noses and throats may not be the only way to detect the breadth of the coronavirus in a community.
Sewage, it turns out, may provide answers as well, and Utah scientists are eager to launch a pilot project to find out.
If the project bears fruit, it could help determine the rates of COVID-19 infection in particular communities and perhaps provide early warnings for new outbreaks, according to Erica Gaddis, director of the Utah Division of Water Quality.
“We are about to launch a pilot with eight wastewater treatment facilities and three universities to try and determine whether it has utility," Gaddis said. "We don’t know if we will be able to use the data in a way we want, to correlate the date with infections on a community scale. We aren’t there yet.”
The idea for the project comes from Jennifer Weidhaas, a professor of civil and environmental engineering at the University of Utah. Her plan is to build on research taking place at many other universities around the world that harnesses wastewater-testing data. The idea is to carefully screen “influent,” better known as raw sewage, entering treatment plants for the virus, which patients shed through urine and feces, as well as through respiratory means.
“We are tying to help public health officials and citizens figure out when it is safe to return to whatever our new normal is,” Weidhaas said. “We are doing the same test that the hospitals are doing when they test people. It’s more difficult to concentrate the virus in wastewater.”
Such a tool could be of great value because the known COVID-19 infections are believed to be far less than the actual number, especially since up to a quarter of those infected show no symptoms and therefore never get tested.
But, hey, everyone uses the bathroom.
The grand prize of this work is to develop a method that would enable officials to estimate the number of coronavirus infections based on the amount of virus detected in samples of wastewater. If high viral loads appear in a community’s wastewater, then public health officials could know whether people are getting infected before positive tests show up among individuals.
In the Beehive State project, Utah State University will handle samples from treatment plants in Logan, Hyrum and Tremonton; Weidhaas’ lab at the U. will deal with samples from Salt Lake City, Snynderville Basin and the Central Valley Water Reclamation Facility; and Brigham Young University will cover Price and the Timpanogos Special Service District, which treats wastewater from 11 communities in northern Utah county.
“We want to limit the amount of travel,” Weidhaas said. “That’s why we are having BYU do the south and Utah State do the north, so we can cover a broader portion of the state.”
Gaddis estimated the pilot will cover about 30% of the state’s population. Known infection rates vary widely among the communities served by these plants, she said, from a low of 1.24 per 10,0000 residents in Price to 72 per 10,000 in Snyderville Basin.
She hopes the project will yield usable wastewater-testing data within three weeks.
The Utah Department of Health then would correlate samples’ viral loads with the number of known COVID-19 cases and total population within the service areas of the treatment plants that provided the samples, according to environmental epidemiologist Nathan LaCross.
“It could have use in determining areas where there appears to be a higher caseload than we know about,” LaCross said. “That might be an indication that we need to look harder [for infected people].”
Once the wastewater data is paired with infection data, the scientists will know whether sewage could be a reliable indicator of the coronavirus’s prevalence. If so, an invaluable tool could emerge that may help tame the COVID-19 scourge. But Gaddis and LaCross cautioned that there is plenty of work ahead to turn this aspiration into reality.
“We are hopeful enough to put some effort into it," LaCross said. "We are stretched thin, but if the data is good and useful and we are able to match it up with what we know about case counts in various areas, there are a variety uses we can see.”