High Country News
What sewage can tell us about the spread of COVID-19
Back in March, a colleague mentioned testing wastewater for evidence of COVID-19 in human waste. The next day, Wiedenheft drove down to Bozeman’s wastewater treatment plant to see if he could grab a sample. Given how few cases there were in the area at the time, and that 6 million gallons of water flow through the plant daily, he wasn’t sure if the virus would be detectable. But Wiedenheft immediately found evidence of it — and it kept appearing in the four samples he analyzed over the next 10 days. Wiedenheft worked with local officials to continue regular testing as Bozeman became one of the first cities in the world to look to sewage for answers. Now, cities across the Western United States are sampling wastewater for evidence of SARS-CoV-2 as a potential “early warning” system for outbreaks. Scientists estimate that up to 45% of people infected with the virus show no symptoms. Given that asymptomatic people are less likely to get tested, many cases may go undetected. With many areas experiencing substantial delays in swab test results, daily wastewater testing can give scientists an idea of community infection nearly immediately, Wiedenheft said.