Question: I was just reading that sewage can be a good way to trace COVID outbreaks. Is it true?
Answer: Epidemiologists have long been tracing disease through poop, sewage, and waste water systems. Indeed, the early tracking of typhoid cases in the late 1800s revealed it to be spread via excrement and contaminated water. The field of “sewage epidemiology” aka “wastewater epidemiology” is, however, relatively new, having first been proposed (to my knowledge) in 2001 by scientists who hypothesized that mass spectrometry screening could be used to identify drug residues in waste water and trace this back to population drug use. Since then, several studies have been conducted and published, concluding that through the novel mass spectrometry approach, “patterns and trends of drug abuse in local communities can be promptly monitored.” More recently, scientists have suggested using this approach to detect viral outbreaks. And back in March, researchers from Biobot, MIT, Harvard University, and Brigham and Women’s Hospital in Boston launched a pro bono program to test community sewers. As described in a fun Popular Mechanics article from last month, they are “looking for SARS-CoV-2, the virus that causes COVID-19, in people’s poop.”
While I haven’t seen any data from Biobot yet, a pre-print publication was posted just a few days ago exploring SARS-CoV-2 in wastewater in Paris. This study shows that it is possible to track coronavirus in waste water. Using time-trend data, the researchers found that concentrations of the virus in wastewater followed trends in COVID-19 fatalities. Also published just a few days ago was a similar study out of Austrialia (this one is even peer-reviewed!) showing a strong relationship between viral concentrations in waste water and coronavirus cases in Southeast Queensland. Both studies demonstrate that wastewater epidemiology can be a valuable tool for better surveying viral circulation in the population (v. important in case of asymptomatic transmission and limited testing), and can even serve as an early warning system to monitor coronavirus entrance into a given population. Science and Nature both had good articles on this cool new area of science if you want to learn more.