The ultimate goal is for almost all sewage plants to install these coronavirus early warning systems so as to track the spread of Covid-19.
“It would be the first test line,” said microbiologist Hauke Harms, one of the leaders of the study. “You would start with our measurement and then you would know where to go to look for the reasons. Normally it is a hospital, or I don’t know, a factory where you have an outbreak. And then one would have to test the people.”
The concept seems fairly simple: Sewage contains remnants of the virus from human feces. If those concentrations suddenly jump, sewage plants would detect that and alert authorities to take action and begin targeted testing of the area in question.
The sewage plants in the area of the eastern German city of Leipzig — which can serve populations of between 100,00 and 600,000 people — are among those taking part in the study.
“If it would be possible to have an idea of the concentration of coronavirus in the wastewater, we can calculate the number of infected people in Leipzig and this would be very interesting in the coronavirus strategies,” said Dr. Ulrich Meyer, the technical director of Leipzig’s waterworks.
But in reality, it’s not as straightforward. At Leipzig’s main sewage plant, samples are extracted every two minutes as the wastewater streams through 24 hours a day.
The scientists at Helmholtz acknowledge that finding a small amount of genetic material (or RNA) from the virus in a giant river of waste is a monumental task.
“We have a high, high volume of waste waters and it is a challenge to find the traces of the virus in the waste waters,” said Rene Kallies, a virologist working on the project. “So we have liters and we have to scale it down to microliters to get a sufficient amount for RNA extraction and that’s the challenge.”
Yet, the scientists say they could detect a Covid trace surge within a day and transmit that information to local authorities.
Another challenge, the scientists say, is the current low number of new infections in Germany, which makes finding the virus even more difficult and means that a single infected person could skew test results.
“You may have heard about these super spreaders and there are also super excreters, for instance. People who excrete much more virus than others and of course this gives you a wrong idea about the number of infected people,” Harms said.
Germany has been held up as an example of a country that has successfully fended off the worst ravages of the virus. As of Friday, it had reported more than 182,000 cases of Covid-19 with around 8,400 deaths, significantly lower than other European countries.
Tracing the virus in excrement is not new and German researchers are not the only ones working to try and use sewage as an alarm system. In February, scientists at the Dutch KWR Water Research Institute found the virus in six sewage plants in the country, including one that services the main international airport in Schipol. KWR said it has developed a method to monitor the presence of the virus in sewage and said testing wastewater has clear benefits.
“Whereas the testing of individuals requires individual tests, testing in sewage can give an early indication of the contamination within a whole population,” KWR said on its website.
The German researchers believe that testing sewage will be one factor in a web of measures to detect outbreaks.
But they acknowledge there are still problems to work out, although they say they are confident the system will be in place and working in the latter half of 2020, in time to help contain a possible second wave of the coronavirus.
“I think we can offer something before the next wave,” Harms said, referring to a working detection system that can be used by states and sewage systems. “So if the next wave is coming in fall or early winter or so, then we should have something.”