Shedding Light on Missouri’s COVID-19 Sewershed Surveillance Program
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By Echo Menges
It is not common knowledge that the many communities in northeast Missouri participate in Missouri’s COVID-19 Sewershed Surveillance Program. So, let’s shed some light on the subject.
Missouri’s Sewershed Surveillance Program is a collaborative effort between Missouri Department of Health and Senior Services (DHSS), Missouri Department of Natural Resources (DNR), and the University of Missouri (MU), according to the DHSS website.
Wastewater in Edina began being tested at the beginning of November. In other nearby communities, sewershed testing began much earlier. In Hannibal, Macon and Milan, for example, sewershed testing began in July of 2020. In Kahoka, sewershed testing began in June of this year, and, a month after that, sewershed testing began in Memphis.
About the Sewershed Surveillance Project from DHSS
The genetic material from the virus that causes COVID-19 can be present in human waste even when individuals have no symptoms. Tracking the amount of viral genetic material (viral load) in wastewater is an emerging method of monitoring trends of the virus in communities.
Since people may not have symptoms and it can take several days before infected people start to show symptoms, sewershed surveillance can provide early awareness of new or worsening outbreaks. This may be an additional data source to help direct testing and resources to protect public health.
Sewershed surveillance cannot tell us the number of individuals currently infected with COVID-19. However, as data are collected and trends are identified, that information may be helpful to track the progression of the virus in communities and inform public health strategy.
We are testing COVID-19 viral load in the wastewater of more than 50 participating community water systems across Missouri. This is new science for COVID-19 tracking. Missouri is one of the first states to initiate this testing and this is one of the largest scale projects in the U.S.
About SSP Variant Testing from DHSS
Viruses constantly change through genetic mutation. As the COVID-19 pandemic has progressed, several variants of the COVID-19 virus (SARS-CoV-2) have emerged. Some variants may have a selective advantage due to their specific mutations, which might explain why some variants can become dominant over the “parent” strain (original strain of the virus).
In February 2021, the sewershed surveillance team began conducting variant testing of sewershed samples. Samples with sufficient SARS-CoV-2 genetic material are tested and analyzed for combinations of genetic mutations found in variants. Because we are not analyzing entire genetic sequences, our results do not confirm the presence of a variant. However, they are suggestive of the presence and distribution of variants across the state and can help target follow-up in the communities.
How It Works
“They send me the package, which is three 50 milliliter vials in a cooler. Each vial is approximately three-inches long and one inch in diameter,” said Edina Wastewater Superintendent Mike Wriedt. “I take the samples with my normal influent samples we take every Monday morning.”
The samples are part of a composite sample, which is taken by a collection device that collects 50 milliliters of water entering the plant from the sewer system every 30 minutes for 24-hours. From the device, three 50 milliliter tubes are filled, packaged and sent off to be tested.
“I don’t test for COVID. We don’t have that capability – obviously. We take temp, PH and suspended solids, which is just to make adjustments to the plant as needed. These are routine tests we run at the wastewater facility for operational purposes,” said Wriedt. “The samples come from the influent water, which is the water coming into the plant from the collection system. I take them with my normal influent samples we take every Monday morning.”
Because the virus is diluted in the system, operators are not believed to be at risk by collecting the samples.
“Unless I wanted to drink it,” said Wreidt. “And I don’t. We do not come into contact with raw sewage. This is part of our practices and safety protocols. You can pick up a lot of things from the sewer.”
Once the samples are collected a statewide courier picks them up and takes them to a lab to be tested. The information gathered is used to help predict spikes in positive COVID-19 cases for the communities in the program.
The information collected in Missouri’s Sewershed Surveillance Program is shared with county health departments, wastewater operators and the public via the DHSS website. Anyone interested in looking at the concentration of COVID-19 and the various variants present in a community that is part of the program can online at: https://storymaps.arcgis.com/ stories/ f7f5492486114da6b5d6fdc07f81aacf.