Sewage can indicate virus spread before symptoms appear

Sewage can indicate virus spread before symptoms appear

In hundreds of cities across the USA, scientists hope monitoring systems will provide an early warning if coronavirus infections reemerge as communities in some states cautiously reopen.

These monitors don't rely on testing patients or tracing contacts.

All that's required? Human waste.

Over the past few months, private companies and university researchers have partnered with communities to collect sewage at treatment plants and test it for the presence of the novel coronavirus. The results are reported to municipal governments and state health officials to help them monitor the situation.

Testing wastewater can reveal evidence of the coronavirus and show whether it’s increasing or decreasing in a community, said Ian Pepper, a professor and co-director of the University of Arizona’s Water and Energy Sustainable Technology Center, one of the groups tracking the virus through different municipal sewage systems.

Although they cannot determine the exact number of COVID-19 cases from the wastewater, researchers said they can estimate the potential case count based on the amount of genetic material detected, the number of customers per system and the volume of wastewater generated. They continue to improve upon those estimates, trying to achieve greater accuracy. 

They need a better understanding of “how much virus is shed in the stool” when someone is infected, said Newsha Ghaeli, president and co-founder of Biobot Analytics, a startup company formed by a group of researchers with the Massachusetts Institute of Technology that is heavily involved in the emerging science. 

“As our understanding of this evolves, and as Biobot collects more and more data,” Ghaeli said, “our case estimates will be refined.”

When the coronavirus attacks a person’s body, it leaves a trail of castoff genetic evidence that winds up in wastewater flushed from toilets across a community.

Scientists watched this spring as that evidence emerged at sewage treatment facilities in California, Florida, Massachusetts, Paris, Australia and the Netherlands. By sampling the wastewater, researchers detected COVID-19 hot spots days, and sometimes weeks, before those cases appeared in hospital admissions data and clinical testing.

Sewage can indicate virus spread before symptoms appear

Such early detection – the virus marks the body before or even without the development of physical symptoms such as a fever or cough – is aimed at helping communities better respond to the pandemic. Officials can issue stay-at-home orders to prevent further spread. Hospitals can stock and staff ahead of a wave of patients. 

The information can help local governments, many of which are reporting declining COVID-19 cases, spot the first signs of an anticipated autumn resurgence. And it can help them measure the effectiveness of their actions. In Paris, the utility provider reported finding coronavirus particles in wastewater before cases began to grow exponentially, then it observed the quantities decrease as a result of a lockdown. 

Hundreds of communities

Promising results from initial studies have spawned widespread interest, and the science is expanding to hundreds of public utilities across the USA through a collection of initiatives.

Most prolific is Biobot Analytics, which worked with local governments to track the prevalence of opioid use through wastewater testing before shifting focus to COVID-19 this year. It monitors wastewater data from 400 communities across 42 states. 

Using $6.7 million in seed money and collaborating with researchers at MIT, Harvard and Brigham and Women’s Hospital, Biobot provides the testing for free.

The company concluded that wastewater sampling in Massachusetts and Delaware indicated a bigger coronavirus outbreak than reported through hospital admissions and clinical testing. In New Castle County, Delaware, the estimates were 15 times the laboratory-confirmed cases.

“This is a high-level way of getting a quick snapshot of the scope of a virus in a community,” Ghaeli said. “We’re hopeful this data becomes very useful in the long run, when we have opened up again, in determining the reemergence of the virus.”

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The sewage surveillance, in concert with clinical testing and reported cases, can give officials a broad look at COVID-19 in their community, Ghaeli said. Biobot provides the numbers to participating utilities, which in turn provide the data to officials and health departments, she said. 

In early April, the utility in Albany, Oregon, started sharing with Biobot weekly samples of pre-treated sewage from the Albany-Millersburg Water Reclamation Facility.

The weekly sampling occurs alongside routine water testing, meaning little additional work for the staff, said David Gilbey, the city’s environmental services manager. It costs about $120 a week for sample bottles and shipping, according to the city’s website. Results usually come within a week, Gilbey said, and are shared with the county health department.

The research holds “much promise,” Gilbey said. The community has seen declining coronavirus cases and things are starting to reopen, he said. If the wastewater numbers increase, that information would help the utility and local governments “get ready” by adding social distance measures or stockpiling more resources.

“It kind of gives us an idea of what we may be in for over the next couple of months,” he said. 

At the University of Arizona, Pepper chairs one of the many committees looking at how to handle the possible return of students to campus this fall. He said the university will sample the campus wastewater for at least a year to monitor coronavirus levels.  

In Detroit, officials announced Monday they are refocusing a 2-year-old study with Michigan State University to try to detect COVID-19 in the wastewater. The study was originally designed to determine whether they could track disease-causing viruses in the city's sewer system.

City health officials said the Detroit study found viruses in the sewer collection system about one to two weeks before those same viruses showed up in health department data.

From November 2017 to February 2018, then from October 2018 to March 2019, samples were collected weekly before treatment at Detroit's Water Resource Recovery Facility.

Looking for disease

Scientists hope to promote development of a national wastewater surveillance network to monitor and respond to not just the coronavirus but all kinds of infectious diseases, Ghaeli said. 

In Israel, a wastewater-based monitoring system for polio started in 1989. In 2013, when the surveillance indicated a polio outbreak was occurring, government officials swept in with polio vaccines and prevented any cases of paralysis.

Sewage can indicate virus spread before symptoms appear

Routine sampling for emerging viral diseases isn’t standard practice at most wastewater treatment facilities. Ghaeli hopes it will become permanent and so prevalent that the information is integrated into public health decision-making.

Monitoring wastewater could be especially beneficial as an early warning in a “micro context,” for example at nursing homes or care facilities, where the rapidly spreading coronavirus has been responsible for many deaths, concluded a group of researchers led by Gorka Orive, a biomedical researcher at the University of the Basque Country in Spain. 

Even in a larger context, such as a neighborhood or city, the information could help officials adopt more focused and balanced measures, including restricting movement,  the researchers wrote in an article to be published in the Elsevier journal Science of the Total Environment. Early warnings, the group wrote, could save lives.

Scientists have studied disease in sewage for years, said Kyle Bibby, an associate professor in civil and environmental engineering at Notre Dame. Researchers in Sweden showed two decades ago that a single infection in one person could be detected in the wastewater from 10,000 people.

As genetic research advances and many groups monitor wastewater for the coronavirus, the science is moving very fast.

“Everyone is sort of learning as they go,” Bibby said.

Bibby’s team works with dozens of utilities, and the research groups collaborate and share what they learn, he said. 

More than a dozen research papers have been published, some in pre-print without full peer review, since the beginning of the year. 

Additional research is planned. 

“This is definitely a community effort,” Bibby said, “through a broad, scientific community.”

Dinah Voyles Pulver is an investigative reporter and environment writer for the USA TODAY Network. She can be reached at [email protected]

Contributing: Frank Witsil, Detroit Free Press

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