On a Sunday morning in March 2020, right at the start of the pandemic, an article in Popular Mechanics caught engineer Pieter Van Ry鈥檚 eye. It had a catchy title: 鈥�.鈥�
鈥淎t the end of that article, it said, 鈥業f you have a wastewater facility and you鈥檙e interested in participating in this study, please contact us,鈥欌�� he said.
As a matter of fact, Van Ry did have a wastewater facility. He is the director of , a wastewater treatment plant in Englewood, Colorado, that serves 300,000 people. He filled out the form, and South Platte joined the first facilities in the nation to start testing wastewater for covid-19.
Now, as the federal government expands its , Colorado has begun to extend its surveillance project to the entire state. The state鈥檚 public health agency is now working with 47 wastewater utilities that serve about 60% of Colorado鈥檚 population.
People infected with SARS-CoV-2, the virus that causes covid-19, shed viral RNA 鈥� genetic material from the virus 鈥� in their feces. In wastewater tests, scientists use that RNA to tell what鈥檚 there.
Rachel Jervis, an epidemiologist with the Colorado Department of Public Health and Environment, noted that wastewater testing can offer an early warning sign about where covid spread is highest. 鈥淲e found that up to 50% of people will shed covid virus in their stool regardless of whether or not they have symptoms,鈥� she said.
The state compiles the data from a variety of sites on a . It also shares its numbers with the Centers for Disease Control and Prevention. About $9.4 million in federal funds is paying for the state鈥檚 wastewater testing project from January 2021 through at least July 2023. The total includes personnel, supplies, equipment, and contracts.
From the start, lab results from the South Platte plant鈥檚 samples showed exactly what the virus was doing, Van Ry said: 鈥淚t was spreading rapidly through the community.鈥� He showed a slide of data from samples. All the surges were clear: alpha, delta, and then a spectacular spike driven by the omicron variant in early 2022.
The South Platte team sends the wastewater samples it collects to a Massachusetts company called . Its mission: 鈥減opulation health analytics powered by sewage.鈥�
The technique caught on around Colorado and the country. Colorado Mesa University, in collaboration with the Broad Institute of MIT and Harvard, was in the state.
, director of the state lab in Denver, said Colorado鈥檚 public health agency started testing wastewater five years ago for foodborne illnesses like salmonella. 鈥淲e were able to pivot that expertise toward covid-19 as the pandemic emerged, and build upon that expertise within the laboratory,鈥� she said.
While the approach is groundbreaking in the U.S., it鈥檚 been used overseas for decades in polio eradication efforts. 鈥淭hey use it essentially the same way we do 鈥� to look for communities where polio is circulating and then use that as a trigger for additional clinical surveillance in those communities,鈥� Amy Kirby, CDC microbiologist and team lead for the National Wastewater Surveillance System, said during a .
In fall 2020, during the first weeks of the school year, a response team at the University of Denver started pulling samples from pipes on campus.
, a mechanical engineer who oversees the campus鈥檚 saliva testing lab, said a wastewater sample taken at one dorm early in the semester showed high concentrations of the virus. 鈥淚t was a million virus units per one liter,鈥� she said. 鈥淗oly Toledo!鈥�
School officials had the dorm鈥檚 residents undergo rapid nasal testing. The wastewater data, followed up with quick testing, allowed school officials to quickly identify and isolate 10 infectious students.
Without that, Lengsfeld said, perhaps 100 more students in the dorm of 300 might have caught it. 鈥淚t works,鈥� she said. 鈥淚t definitely is a case study, I think, of exactly how to control spread.鈥�
Jude Bayham, an assistant professor at Colorado State University and the Colorado School of Public Health, said that as overall covid trends improve and Colorado pivots to the next phase 鈥� and maybe scales down other testing 鈥� still-evolving wastewater analysis promises to step up. 鈥淲astewater surveillance is a relatively cheap alternative that can provide a lot of information,鈥� said Bayham, who is also a member of the state鈥檚 covid modeling team.
That kind of information can guide coronavirus response.
鈥淲e are really excited about this new tool,鈥� said state epidemiologist Dr. Rachel Herlihy. 鈥淚t will help us understand regional differences. It鈥檚 also been incredibly useful for us in understanding the emergence of new variants.鈥�
鈥淲e鈥檙e still really figuring out how to best put it to use,鈥� Herlihy added.
Kirby, of the National Wastewater Surveillance System team, said the CDC anticipates using the system to monitor infectious diseases, as well as other public health issues, like substance use disorders.
鈥淥ne of the strengths of wastewater surveillance is that it is very flexible,鈥� Kirby said. 鈥淪o once we have built this infrastructure to collect the samples, get them to a laboratory, get the data to CDC, we can add tests for new pathogens fairly quickly.鈥�
Should a new pathogen of interest pop up, she said, they could ramp up this system within a few weeks to start gathering community-level data on it.
This story is part of a partnership that includes聽,听聽and KHN.