Household wastewater tracking, a strategy epidemiologists have long used to study how diseases spread, has helped Clackamas County health officials chart coronavirus presence in the community.
Clackamas Water Environment Services (WES) is among wastewater departments nationwide that have been invited by the Centers for Disease Control and Prevention to participate in the National Wastewater Surveillance System, launched in 2020 to provide an early warning signal of COVID-19 surges.
"Wastewater surveillance allows us to monitor and track the trends of SARS-CoV-2 concentrations in wastewater, and when used alongside other data sources, can support our public health response," said Allina Cannady, epidemiologist for the county's Public Health Division.
Cannady and fellow epidemiologist Anna Menon helped identify potential concerns in wastewater samples shared with LuminUltra, a company partnering with the CDC to test samples from across the nation.
From mid-February to early April, COVID-19 indicators were studied in wastewater samples from three WES-operated sewage-treatment plants, including the Tri-City Water Resource Recovery Facility that serves Gladstone, Happy Valley, Milwaukie, Oregon City, West Linn and unincorporated county areas.
Samples were also collected from WES's Kellogg Creek facility, serving Happy Valley, Johnson City, Milwaukie and urban areas of North Clackamas; as well as the Hoodland facility serving Welches, which officials say is a smaller system in comparison to the other two provides a more accurate trend indicator.
"The more targeted the scale, the more useful the data," said Ronald Wierenga, environmental services manager for WES. "The bigger the system, the less valuable wastewater monitoring is. That's why our Welches facility provides the more useful information."
According to the CDC, wastewater testing can provide efficient data recording for communities that do not have access to timely clinical testing for COVID-19. Data can also be used to study trends across different communities living within an area.
Wierenga noted that the group effort between WES and county health officials exemplifies the importance of collaboration between local departments specializing in different areas.
"This is epidemiology. This is not what we typically deal with," Wierenga said. "We deal with parasites and toxins. When we get results on that, we know exactly what we are dealing with. So the interdepartmental piece is so important."
For more information about wastewater surveillance data, click here.
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