What’s the Scoop in the Poop? Sewage Offers Early Warning System for COVID Trends


Editor’s note: Not long after the arrival of COVID-19 in Michigan in early 2020, some municipal wastewater systems began monitoring for signs of the virus in their treatment plants. Later, state government funding expanded the program. Rather than waiting for cases to climb, public officials may be able to use sewage surveillance to forecast a surge of infections through monitoring. An on-line dashboard provides information on levels and trends across the state.

FLOW interviewed Chelsea Wuth, Associate Public Information Officer of the Michigan Department of Health and Human Services, about results of the program.

What lessons have you learned from the monitoring thus far? Any surprises?

Wastewater monitoring, especially for SARS-CoV-2, is a relatively new field still in development and, therefore, is still evolving and will continue to do so. However, there has been great progress in the development of laboratory testing methods and analysis of the resulting data. One finding is that while most of the sampling locations analyzed so far have detected the SARS-CoV-2 virus in the wastewater before corresponding COVID-19 cases are reported, the length of time for this “early warning” appears to vary greatly by location.

Another outcome is how the wastewater monitoring data from different types of sampling locations is being used at the local level. Some sampling locations are very large (thousands to over a million people) and provide a large-scale picture of COVID-19 transmission in that community, which can be used to confirm COVID-19 data from other sources and to inform public health messaging. Conversely, increases in virus levels at smaller, facility-level locations may result in more targeted public health actions, such as increased clinical testing that can potentially identify cases before larger outbreaks occur. A report details the successes of the pilot program.

There have been many program partners, including the Michigan Department of Environment, Great Lakes, and Energy, local health departments, academic and private laboratories, wastewater utilities, and municipal governments that are participating in and supporting this effort. The strong relationships have been instrumental to standing up such a large effort.

How will the knowledge gained from this experimental program be used?

Local health departments and their partners can use this data to track COVID-19 in their communities and inform their public health responses.Using this data in conjunction with clinical case data, some local health departments have increased their clinical testing and their communication and outreach efforts in communities where increased viral levels were detected in wastewater. Some participating universities and congregate living facilities use wastewater surveillance data to focus their clinical testing efforts on campus or at their facility to prevent further COVID-19 transmission.

Does the project have application for other diseases?

The wastewater monitoring project is anticipated to continue as a part of Michigan’s COVID-19 response through July 2023. After that, wastewater testing in Michigan will depend on state and federal funding priorities. Beyond the COVID-19 pandemic, there is potential for this type of monitoring to be expanded to detect other diseases in wastewater. Potential examples of this include other respiratory viruses, gastrointestinal viruses, and antibiotic resistant organisms. Having the laboratory methods, infrastructure, and workforce already established through this network will be beneficial to any future applications.

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