The coronavirus pandemic has all of us locked down indefinitely, and it's hard to know at this point just how far we are from a light at the end of the tunnel. The White House has been signaling a return to normal as soon as the end of April, while actual experts suggest quarantine may need to run for months — or even be reinstituted should additional waves of the virus hit. The uncertainty has people looking for answers wherever they can find them. In the case of several research groups highlighted in the journal Nature, that includes using poop as a potential indicator.
Scientists around the world have tapped sewage and wastewater as a new tool that can help us understand the spread of coronavirus. Researchers have been able to find traces of COVID-19 in urine and feces, and believe that analyzing the waste could help to determine if the spread of the virus is starting to slow — or if it might be ramping up again. The method — which has already been successfully tested in the Netherlands, United States, and Sweden — requires researchers to extract wastewater as it travels through drainage systems on its way to a treatment facility. Treatment facilities can capture waste from more than one million households, according to Nature, which provides a significant sample size with which to draw from.
The method also may provide a more complete understanding of how widespread the virus is within a community in a way that testing cannot. For the most part, testing has been performed on people who have shown symptoms of coronavirus or have been in contact with someone else who has tested positive. But the Centers for Disease Control and Prevention now report that between 25 and 50 percent of carriers are completely asymptomatic, showing no signs of illness. That means there could be many more people infected than we are aware of. The traces of the virus in their systems would be identified in wastewater testing, providing a more complete picture for those who are unlikely to go to the doctor to get tested.
Examining human excrement to project a full model of infection is far from a perfect science. Researchers will have to determine just how much coronavirus tracings can be found in the waste, then extrapolate that out to estimate how many people are infected. They will also need to ensure the tests provide a representative sample rather than a single moment in time, which could require regular testing. But, if implemented, this testing method could provide clear indicators when infections have peaked and are starting to decrease, according to researchers who worked on the study.
The waste surveillance could also be used to monitor for upticks in the spread as well, which might indicate a new wave of infections. That's an increasing concern — that even if we flatten the curve of COVID-19 cases, the virus could be back and may require more vigilance in the form of another quarantine. While some world leaders ignored the early signs of COVID-19's initial spread, maybe they'll heed the warning of our collective poo.