A new research project could allow university and city officials to trace asymptomatic individuals with – you didn’t guess it – feces and urine sampling.
University of Florida researchers are testing wastewater samples for the presence of the virus that causes COVID-19, potentially helping to identify hotspots of the virus on campus — even among asymptomatic people.
But nearly six weeks into the semester, cases on campus are too widespread for the results to provide a clear indicator of where exactly hotspots are developing.
Through ongoing research, scientists are still learning how the virus behaves in wastewater. But based on several studies nationwide, including here in Gainesville, scientists have found a way to detect the genetic material of the coronavirus by testing wastewater from sewer lines.
Early detection could help prevent outbreaks
The UF study closely trails a similar effort led by researchers at the University of Arizona. The school’s officials said the wastewater testing may have helped contain the spread of COVID-19 in its on-campus dormitories by identifying the presence of the virus in sewage samples.
University officials then tested every student in the dorm and found two asymptomatic students who tested positive and were put in isolation. A few hours after those two students were removed, the samples showed no presence of the virus at all.
The technique has been used to identify potential cases at other universities as well.
But several factors could influence the accuracy of these test results. For example, the shedding rate — how much and how quickly a person excretes the virus — varies from person to person and fluctuates throughout the stages of the disease.
Additionally, the sewage testing cannot reveal how many people in a community have COVID-19 based on how much of the virus is detected in the samples.
UF has had a significantly higher volume of cases than the University of Arizona since fall semester classes began. This makes it more difficult to pinpoint individual buildings as potential hotspots, said Joseph Bisesi, an environmental toxicologist and lead researcher for the project.
“The only issue here on campus is that we just have a pretty good number of cases here,” he said. “Because there’s so many, it’s a little bit more difficult to find those asymptomatics when there’s all these positives … in a fair number of the samples.”
Bisesi added that he expects the wastewater testing technique to become more effective if and when cases subside. That way, it will be more obvious when a sample comes back with coronavirus RNA, the genetic material, for a particular area like a dorm.
The project has been ongoing since late May. The joint effort among researchers Bisesi, Anthony Maurelli and Tara Sabo-Attwood was inspired by an earlier effort in mid-March to test fecal samples of patients who may have been asymptomatic. In early May, the research team collected its first wastewater sample from the treatment plant in Cedar Key, a small coastal city southwest of Gainesville.
Sampling of campus sewage didn’t begin until fall classes started in early September, mainly because there was little to no flow from buildings, Bisesi said.
With the help of UF facilities service staff, the team takes about seven or eight daily samples from 28 locations on campus via manholes, which offer above-ground street access to the underground sewer pipes.
Back at the lab, researchers concentrate the sample, extract the genetic material from the virus and perform the same process that is used for nasal swab tests. After samples are collected, Bisesi said it takes about 24 hours to test the samples and get results.
Wastewater monitoring is a work in progress
While they hope the project will eventually be able to help identify hotspots, it is currently useful for observing general trends, said Maurelli, who is a molecular biologist at UF.
At the city level, he said, samples taken from wastewater treatment plants in Cedar Key and Gainesville can help determine whether increased cases correlate with increased detection of the virus in wastewater. Similar efforts are taking root across the country, including a wastewater monitoring initiative led by the Ohio Department of Health.
“It’s a way of getting a measure of the health of the community,” Maurelli said.
It is unclear whether all UF students in a single dorm would be tested when the virus is detected in wastewater samples.
At a September Alachua County Commission meeting, Paul Myers, the local Florida Department of Health administrator, said the majority of Alachua County’s transmission has stemmed from and been contained on the UF campus. Confirmed COVID-19 cases have been linked to dorms, on-campus apartments and sorority and fraternity housing.
“Any type of surveillance and any type of monitoring that we can use to better understand what’s going on in a community is a helpful tool,” said Dr. Michael Lauzardo, director of the UF Health Screen, Test and Protect program.
Students were not required to get tested for COVID-19 before moving into dorms and other on-campus housing in the fall, but they were required to complete an online screening questionnaire to be cleared.
“That’s why isolation and quarantine are so critical once you identify a case, because we can then short-circuit the transmission pattern,” Lauzardo said.
Although free testing is now available for UF faculty and students on a weekly basis, Lauzardo said UF does not have the capacity to test upwards of 70,000 people each day based on the sewage testing results.
“I foresee wastewater epidemiology being an important part of one of the many tools we’re going to use to keep campus as safe as possible, and control the spread as much as possible,” he said.
Wastewater as a means of detection ー not infection
While evidence of the coronavirus has been found in untreated wastewater and fecal samples, nobody has contracted the virus from exposure to wastewater, according to the CDC.
“The unknown is what is an infectious dose,” said Jennifer McElroy, senior environmental engineer for Gainesville Regional Utilities’ water and wastewater services.
Even if evidence of COVID-19 is found in raw wastewater samples from the treatment plants, McElroy said it would merely indicate that some unknown number of people on a certain side of town — depending on which wastewater plant is sampled — have the virus.
GRU estimates that 95% of its service area in Gainesville relies on a centralized sewer system for sewage disposal. Within that, approximately 850 miles of pipes transport sewage from homes, buildings and other establishments to either the Kanapaha or Main Street water reclamation facilities.
Unlike septic tanks, centralized sewer lines offer the opportunity for researchers to collect waste for entire buildings. Sewage makes its way through the city’s sewer pipe infrastructure via gravity or pumps (known as lift stations) until it reaches a wastewater treatment facility.
With the exception of a few small buildings that use septic tanks, all buildings on UF’s campus are connected to its own network of sewer lines. Sewage ends up at the UF Water Reclamation Facility located at 1103 Gale Lemerand Drive.
Wastewater is treated in accordance with EPA guidelines and permits, McElroy said.
“We work very, very closely with our regulators because we want to produce a product that can be reused beneficially in the environment,” she said.
The wastewater treatment process removes any viruses, bacteria and other pollutants that may be in human feces.
McElroy also emphasized that reclaimed wastewater from GRU’s treatment plants is not used as drinking water. Rather, some reclaimed water is deposited deep underground to recharge the Florida aquifer, which will supply the state’s drinking water hundreds or thousands of years from now.
“You will not have COVID in your drinking water,” she said. “There is no connection between wastewater and drinking water here.”