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UNR Research: Coronavirus prevalence in wastewater reflects community infection rates


University of Nevada, Reno, researchers announced today that the SARS-CoV-2 virus has been found in regional wastewater at low levels, reflecting what they said are reduced cases of COVID-19 in the area.

“The latest data shows very low to non-detect viral levels in wastewater suggesting a consistent reduction in COVID-19 prevalence in our community,” said Krishna Pagilla, a UNR environmental engineering professor and leader of the study.

Sampling and testing were conducted at the three water reclamation facilities and at 12 sewer sites beginning in April last year just after the coronavirus disease started spreading throughout Washoe County. 

“The data we collected from the many sites shows that the monitoring reflects what’s happening in the community,” Pagilla added. “It clearly reflects the extent of the disease as it was determined by human testing, so it is a good leading indicator of what’s happening in the community.”

The data indicate whether COVID-19 is increasing or decreasing in the community.

“Using the monitoring samples, we can’t separate out just the vaccine effect, but overall if the pandemic is decreasing and the number of cases is going down – that we are able to clearly see through wastewater-based monitoring,” Pagilla explained. “So, by doing more frequent monitoring we can really see whether the pandemic is going away or if a resurgence is happening. Now we are in position to do that.”

The group collected more samples from August through December of 2020.

“The majority of wastewater in the community comes through the Truckee Meadows Water Reclamation Facility,” TMWRF Manager Michael Drinkwater said. “So, testing the wastewater is a good leading indicator of what’s happening in the community.”

Drinkwater said that the virus is not getting past the wastewater treatment facility.

“We looked at the entire treatment process, which included the influent and effluent,” he added. “The virus was clearly detected when coming into the plant, but not detected in the outgoing, so we can say definitively that the virus does not survive the wastewater plant and the water going back to the Truckee River is free of the virus.”

More sampling, although limited, is likely to continue for another year. Sample sites at each plant will include raw sewage and the finished effluent. Reno, Sparks and Washoe County governments helped to fund the research through CARES Act dollars.


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