London’s super-sewer

Could sewage be key to detecting coronavirus spikes?

Image credit: James o’Jenkins, Tideway

University of Michigan and Stanford University researchers are investigating how the novel coronavirus travels through the environment, including whether it could be detected through sewage surveillance.

If the presence of the coronavirus (such as viral genetic material) can be detected in sewage, this could inform measures to contain the virus even when people are asymptomatic and unable to access testing kits.

“One of the key areas we’re exploring is whether we can detect this new virus, SARS-CoV-2, in a community’s wastewater before it’s known to be circulating there,” said Professor Krista Wigginton, the project leader at Michigan. “The case numbers we’re seeing reported in the US and lots of other places are dependent on how many test kits we have, so the curve displaying a number of cases is more of a curve of test kit availability in a community. What we see in wastewater may look totally different.”

While this method would not give precise numbers of cases, it would allow for estimates which do not rely on individual testing – with the possibility of much faster detection in local surges – and which are less prone to measurement bias.

“We could identify areas with rapidly increasing cases as a warning system to the healthcare system,” said doctoral student Nasa Sinnott-Armstrong. “Finally, these numbers can help epidemiologists model the trajectory of the pandemic with far less testing burden on our healthcare system.”

Sewage surveillance is already used in Israel to monitor circulation of poliovirus. When it comes to potentially detecting the novel coronavirus in sewage, however, there are many unknowns, such as whether it can be detected in wastewater at all. Since early March, the Michigan and Stanford researchers have been gathering wastewater samples from a pilot scale wastewater treatment plant which treats sewage from Stanford University’s campus and several local municipalities.

Over the next few weeks, the researchers will begin analysing the samples.

If their searches through wastewater are in vain, this may not mark the end of their search; they hope that they may still be able to find the novel coronavirus sticking to more fetid matter.

“In addition to collecting wastewater influent samples and archiving them, we’re also grabbing primary solid samples,” said Wigginton. “Our previous work suggests that these viruses stick to wastewater solids more than other viruses. We’re hopeful that we’ll be able to detect something.”

The scientists have been granted a rapid response grant from the National Science Foundation to support their work, which will also include studies of how the virus responds to ultraviolet light and how the virus transfers between fingers and inanimate objects.

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