The recent spike in COVID-19 cases in Cache County was detected in sewage at the Hyrum and Logan wastewater treatment plants before it showed up in human test results.
The Utah Division of Water Quality started collecting coronavirus data from 10 treatment plants around the state representing roughly 40 percent of the Utah population as part of a pilot study launched in March. It just so happened the study was in progress when COVID-19 cases — many linked to the JBS meat processing plant in Hyrum — started rising dramatically in Cache County.
“The initial results show that we can not only detect the virus in sewage but we can see trends that are broadly consistent with known infection rates in Utah’s communities,” said DWQ Director Erica Gaddis in a press release Thursday that noted local sewage testing results mirrored the increase in active case counts in Cache County. “Monitoring virus in Utah’s sewage systems offers a tool for early detection of rising infections, monitoring community infection trends, and confirmation of low infection rates. We hope that monitoring the sewage can help in prioritizing limited state resources such as mobile testing.”
Jeff Ostermiller, a senior scientist with DWQ, said evidence of the rise in Cache County infections was visible about a week before the Bear River Health Department started seeing high numbers from its testing of individuals in the community. The evidence was not as strong as researchers would have liked, however, because the study was winding down at that time and sewage-testing frequency had been scaled back from twice a week to just once a week.
“The spike occurred at the end of the pilot, but there is some evidence to suggest that you can actually detect changes, particularly increases, in infection rates five to seven days prior to noticing that in the community, because it takes a while for symptoms to manifest and for people to get tested and for results to come back,” Ostermiller said. “So if this holds, then obviously there is promise in terms of helping us get the right kind of medical resources to the right places.”
As a result of the study findings, the Utah Coronavirus Task Force on Thursday requested DEQ increase the frequency of sampling from the Hyrum and Logan plants and get additional samples from “interceptors” that feed sewage from communities that contract with Logan for wastewater treatment. That way, hot spots for COVID-19 could be more closely pinned down with data.
The state will also expand testing from the 10 pilot-study sites to around 30 wastewater facilities statewide.
“They’ve asked us to do a bit more frequent sampling in Logan to see if we can measure changes in the response efforts that are going on right now,” Ostermiller said.
The pilot study was conducted by DWQ with help from researchers at Utah State University along with Brigham Young University and the University of Utah.
USU biological engineering professor Keith Roper was among the researchers involved and told The Herald Journal on Thursday the process proved to be a scientific awakening of sorts for him.
“I frankly was initially a skeptic. These wastewater samples are highly complex and not well defined, and the fact that one could get a quantitative, reproducible, reliable signal from such a complex sample that is subject to so many variables was to me quite dubious initially,” Roper said. “After having participated in the work for two or three months, I’ve come full circle.”
Roper said the testing of sewage is the same as that done on humans as developed by the Centers for Disease Control and detects the “footprint” of the coronavirus rather that the virus itself.
“The method that we use incorporates a CDC protocol for testing for the nucleic acid of the virus, so we’re analyzing for the RNA that comprises part of the sequence inside the virus capsid.”
He said the Utah study adds to a growing body of evidence that sewage testing can provide profile of disease spread in a community.
The DWQ press release noted the virus was not detected in water leaving the sewage treatment plants and discharged to natural bodies of water. Also, virus levels within the plants are not considered significant enough to pose a serious threat to wastewater workers.
“Most of the time, by the time the virus actually reaches the sewage treatment plant it isn’t active, and by the time it gets treated there’s no sign of it,” said DWQ public information officer Jared Mendenhall. “That’s one of the reasons they are looking for genetic material from the virus.”