Poop Sleuths: Why Researchers Are Tracking Coronavirus in Wastewater

Ourpoopis made up primarily of water, but剩下的25%is a cocktail of undigested food residue, fats, salts, mucus andhuman pathogenslike bacteria and viruses. If you're infected with the coronavirus, which causes the COVID-19 infection, then it'll show up in your excrement, too.

The stuff that washes down the drains of our toilets, as well as sinks, tubs and street gutters, travels for miles through our community'ssanitary sewer systemand gathers with the waste from other homes into bigger and bigger sewer pipes. This river of communal sewage eventually flows into a localwastewater treatment facilitywhere it is ultimately pasteurized and the harmful material removed.

Regularly monitoring wastewater samples over the course of time enables researchers to establish a trend analysis. These analyses have detected spikes and new variants days — even weeks — before COVID-19 testing via nasal swabs. And since all cities and towns have their own sewage plants, researchers can pinpoint where spikes will be and whether a new variant is emerging as one of concern.

"Imagine if you had two weeks' lead time in a potential outbreak situation at a dorm or a hospital or other facility," Smyth says. "You could potentially target your interventions and maybe reduce the impact of that outbreak."

For example, communities could ramp up messaging to alert the public topractice masking, social distancing and other measures to limit the spread of the virus as well as encourage testing and self-isolation for those who test positive.

Surveillance also gives researchers a better understanding of how the virus mutates and how those variants react to vaccines — factors that are vital to keeping the public safe. "We need to understand the virus because we don't know where it's going next," Smyth says.

Public health officials have learned a lot about COVID-19 bytracking the number of positive testsby county, state, country and more. But testing has its limitations.

For starters, it requires people to actuallyget测试。许多做如果他们成为暴露在病毒传染s, have developed symptoms, or are required to do so for their jobs. But not everyone in a community chooses to get tested either because they don't have health insurance, have no access to tests, aren't showing symptoms or simply do not want to get tested. "If you don't get tested then we don't have any data from you," Smyth says.

However, "everybody poops," she adds. "Everybody has to go to the bathroom so [thanks to wastewater testing] we have the data on potentially every single person in a system."

Of course, wastewater testing for coronavirus is not mandated so not all municipalities are testing. But many are voluntarily participating thanks to grants and othersources of fundingincluding theCARES Act。Several municipalities created their own dashboards to share their data and trend analyses.

In September 2020, the Centers for Disease Control and Prevention (CDC) launched theNational Wastewater Surveillance Systems(NWSS) to coordinate and build on the country's capacity to track SARS-CoV-2 in wastewater samples collected at wastewater plants across the country. As part of that project, the agency recently unveiled a newCDC COVID Data Trackerwhere all the data on wastewater testing is centralized onto one dashboard for the public to view.

The CDC expects participation in the program to grow as health departments and public health laboratories further develop their capacity to coordinate wastewater surveillance. However, it's still a developing field and there are limitations. Among them, treatment plants don't capture homes onseptic systemsor communities served by decentralized systems that treat their waste, such as hospitals or universities. However, many colleges and universities are collecting their own data, including Atlanta'sEmory University,University of MiamiandUniversity of Buffaloto name just a few.

And while concentrations of the virus in wastewater sampling can indicate just how impacted a community is, it cannot tell exact numbers of those infected. But having all the data on one page — literally and figuratively — can offer a better picture of how the virus is impacting our country. "Having the CDC's leadership and guidance is really going to help," Smyth says.

"Wastewater is very sexy right now. It's all over the news," Smyth says. "But here's the thing — people have been using wastewater surveillance for years to look for things like polio, for example."

Yep, that's right. Researchers have been detecting and tracking various viruses in sewagefor more than 50 yearsand have used the data to guide public health responses.

For example,polio has been eradicatedin nearly all countries, thanks to the polio vaccine. Buttransmission is still ongoingin three countries where vaccines lag — Nigeria, Afghanistan and Pakistan. Rather than relying on reported cases of acute flaccid paralysis (AFT), a probable cause of polio, researchers have been looking in sewage to detect poliovirus shed in the feces of non-paralyzed people infected with polio.

Wastewater surveillance has also been used to detect other viruses such as hepatitis B and norovirus. Smyth says she is currently working to refine testing techniques to better monitor sewage plants for the flu — a virus, she says, that's "very good at causing pandemics."

Understanding the value of our waste "you see it in a whole new light," Smyth says, referencing a comment a local sanitation utility employer recently said to her: "It's only wastewater if you don't use it."