Scientists are studying poop to understand how COVID-19 spreads
LONDON — Poop doesn’t lie.
That’s why scientists are looking at sewers running under the world’s cities and towns for information they hope will help to stem the spread of the coronavirus.
Sewers are treasure troves of information, containing genetic material of COVID-19 shed by those with the virus in their fecal matter — even if they are asymptomatic.
A recent study has also shown that viral levels in wastewater correlated with clinically diagnosed new COVID-19 cases and might reflect disease prevalence before it’s reported by doctors, raising hopes that the sewage could become an early warning system — a canary in a coal mine of sorts — for new outbreaks.
In the United Kingdom, a group of researchers on Thursday launched a cross-country epidemiology surveillance program, dubbed N-WESP network, in what will become one of the biggest international undertakings looking into wastewater surveillance for COVID-19, the disease caused by the coronavirus.
They will be trying to develop models that would correlate viral RNA, the genetic material of the coronavirus, found in wastewater with the actual number of COVID-19 cases in the community that produced that wastewater in the first place.
“Once the science matures, which will hopefully be on the order of a few months, we will be helping to provide the methods that will be used to generate the data needed to inform decisions on lockdown,” said Andrew Singer, the project’s chief researcher and senior scientist at the U.K. Centre for Ecology and Hydrology.
The U.K. suffered the worst COVID-19 outbreak in Europe with more than 43,900 deaths and 313,000 cases, forcing millions of people into lockdown.
And British health authorities have been testing thousands of people every day to keep track of the virus’ spread as its economy reopens and lockdown restrictions are lifted. However, it’s usually people with symptoms or known exposure to confirmed cases that are screened. It is these asymptomatic people with no symptoms, who can still spread the virus, who are often missed.
That’s where researchers hope sewage testing can come in, using virus genetic material to conclusively quantify how many people in the population are shedding the virus at any given point in time. While it can’t identify which specific individuals have the virus, it gives a more immediate snapshot of the epidemiological situation in a community based on its wastewater profile.
It’s a potentially low cost, anonymous and immediate mechanism for predicting local outbreaks, said Barbara Kasprzyk-Hordern, a professor of chemistry with the University of Bath, one of the researchers involved in the project.
“Wastewater can be really useful in understanding where the virus is spreading even if we don’t necessarily see increased numbers of people in the hospitals, because this happens later and not everyone gets symptoms, so we can provide a truly comprehensive picture of community wide infection,” she added.
The team will probe sewage in cities across England, Wales and Scotland and look at individual nodes in their wastewater systems that feed different parts of the city. That way, health officials can identify any possible hot spots within the confines of that city and move in with targeted restrictions in specific neighborhoods.
“The cost-benefit is, if you catch it early, you don’t lose an entire city and therefore furlough an entire city,” Singer said.
The project will also look into whether the virus that ends up in the sewers could still be infectious, which can have repercussions for how sewage is handled.
“One of the very few positive things that could come out of COVID-19 is that we recognize that there is data within our wastewater, and that data can be a lifesaver,” Singer said.
But he said wastewater surveillance could pave the way for more effective tracing of other infectious diseases, not just COVID-19.
“If many countries develop this capacity and support it into the future, what is less likely to ever happen again is a pandemic spreading across the world for two months when no one knew it was happening,” he added.
William Schaffner, an infectious-diseases expert at Nashville’s Vanderbilt University, told NBC News wastewater surveillance for COVID-19 can help focus public health efforts after the pandemic dies down in the U.S.
“At the other end of the pandemic, as COVID-19 we hope will wane, it can also document the reduction and then elimination of the virus,” Schaffner said.
“At the moment, we have so much COVID-19, I think it would have a limited utility in the midst of an expanding epidemic, because we know the virus is everywhere, but as COVID-19 recedes, it would be interesting to detect hotspots.”