The state health department, two universities and 16 wastewater utilities are partnering to search for signs of new COVID-19 cases before infected people even have symptoms — by looking for the disease in poop.
Sampling wastewater provides an “early warning” system at the population level, John Putnam, environmental programs director at the Colorado Department of Public Health and Environment, said on a press call Wednesday morning. Most people start shedding the virus in their feces about two days after infection – before they’ve developed symptoms and sought testing, he said. While the testing isn’t precise enough to say that someone’s infected in a particular household or neighborhood, it gives a signal of whether cases are increasing or decreasing.
Utilities are collecting samples right before the wastewater enters their plants for treatment, said Jim McQuarrie, director of strategy and innovation for the Metro Wastewater Reclamation District. In Denver, they’ll draw samples twice weekly from two large pipes that serve a combined 1 million people, he said.
The sampling program will cost the state about $520,000, with the utilities donating their staff time to do the sampling. The participating systems serve more than 60% of Colorado residents.
Labs at Colorado State University and Metropolitan State University Denver will analyze the samples, then send the data to the state health department. Health officials will then use the wastewater data, in combination with nasal swab testing and other sources, to get a sense of what areas might need more resources to deal with a growing caseload, said Nisha Alden, respiratory disease and COVID surveillance program manager for CDPHE.
“We consider this another tool in our surveillance toolbox,” she said.
Researchers are still working out how much the level of virus in the wastewater would need to change before it constitutes a meaningful signal, said Nicole Rowan, clean water program manager for CDPHE. It will take at least a few months before they have enough data to start drawing conclusions, she said.
Studies in Europe found a correlation between the concentration of the new coronavirus in wastewater and the number of cases in a community. The research is part of a trend of viewing wastewater as useful, McQuarrie said. Other ideas for the future include testing to get an estimate of illicit drug use, or to see if people are using more asthma medication when ozone levels are high.
“There’s a lot of information within wastewater that tells us about the health and social needs of our community,” he said.
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