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Spread, mitigation of COVID-19 could be tracked in municipal wastewater

Shoppers at the Hollywood farmer's market comply with Mayor Eric Garcetti's orders to the extent that they can in Los Angeles on Sunday. Photo by Jim Ruymen/UPI
Shoppers at the Hollywood farmer's market comply with Mayor Eric Garcetti's orders to the extent that they can in Los Angeles on Sunday. Photo by Jim Ruymen/UPI | License Photo

April 6 (UPI) -- Researchers at the University of Arizona say they may be able to track the presence of coronavirus in communities by analyzing municipal wastewater.

The approach, which can be used to test treated and untreated sewage, may help governments track the spread of COVID-19 and, perhaps, identify cases in people who aren't yet showing symptoms, according to the researchers.

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The method could also serve as a tool to determine whether or not containment initiatives, such as social distancing, are working to eradicate the virus from an area.

"The test looks at total viral load from a community, so that includes people who are asymptomatic," Ian Pepper, director of the University of Arizona Water and Energy Sustainable Technology Center, told UPI. "So that's a big advantage. We should also be able to see whether the pandemic increasing, decreasing or staying the same in a particular region, which I think is very valuable."

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People with no obvious symptoms of COVID-19 may still be able to pass the virus to others, researchers have found, and this "asymptomatic transmission" has likely played a role in the rapid growth of confirmed cases in the United States.

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Local governments have been challenged to track the number of infected, and whether social distancing measures have been effective at controlling spread, at least partially due to a shortage of testing supplies.

Pepper and his colleagues say their approach may help fill in the gaps.

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Environmental microbiologists have used sewage monitoring programs to study pathogenic viruses for decades, most notably as part of efforts to globally eradicate the poliovirus, he said. A study published by the research team in 2008 suggests the approach can be used to effectively spot coronaviruses in general -- and notes that they die off in wastewater, with a 99.9 percent reduction in two to three days.

With their sewage surveillance program, researchers at the WEST Center will use molecular methods and nucleic acid targets recommended by the U.S. Centers for Disease Control and Prevention to detect SARS-CoV-2, the coronavirus that causes COVID-19.

Eventually, the WEST Center hopes to collect samples for evaluation from across the country to correlate viral concentrations in sewage with recorded numbers of infections to help public health officials better track ongoing outbreaks and prepare for future ones.

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The group has already tested samples at the Pima County Wastewater Treatment Plant, in its home base of Tucson, and has begun working with similar facilities affiliated with the California Association For Sanitary Agencies, Pepper added. In Tucson, tests were able to spot SARS-CoV-2 in untreated sewage but not in treated waste, which suggests that conventional waste treatment may kill the virus.

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Further investigations based on sewage surveillance and more recent next-generation sequencing approaches may help identify genetic variants of the coronavirus circulating in the population. Additional research could also assess the effectiveness of mitigation strategies to control and prevent the disease, Pepper added.

"We think we will be able to use this to predict risk," he explained. "Ideally, we'd like to start monitoring wastewater in the fall, so we can see if the pandemic is coming back in certain areas."

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