PURCELLVILLE, Va. — Purcellville's wastewater treatment plant processes water for more than 7,000 residents in the Loudoun County town. Now it’s also protecting them in a new way by trying to detect COVID-19 virus remnants in sewage.
It’s the town’s attempt to see how widespread the infection is – even before people may know they are sick.
"There is a series of calculations that they do to actually quantify the amount of cases in Purcellville based upon the amount of flow that the facility had that day," said Mark Inboden of Inboden Environmental Services.
The technique is called wastewater epidemiology. To do it, Inboden's team takes a small sample, which represents the entire town’s sewage for a day. The RNA genetic markers of COVID-19, non-infectious at that point, pass from the body and remain in water flushed down the toilet. That sample is then run through testing at BioBot’s Boston-area lab.
BioBot first developed its technology for another public health crisis.
"Over the last few years we've been measuring the concentration of about 30 different opioids and related drugs, including illicit opioids like heroin and fentanyl," said BioBot co-founder Newsha Ghaeli.
The first round of testing May 13 estimated 50 cases in Purcellville. That estimate spiked to 320 cases a week later, but went down to 65 by the end of the month.
That spike in cases was similar to a verified spike in new COVID-19 cases in Loudoun County, according to its health department. Estimates aren’t yet available for June.
Purcellville Mayor Kwasi Fraser decided he wanted an early warning system for Purcellville and brought in BioBot.
"Now that we have this knowledge, we will provide that information to the health department and this will assist us in potentially getting more support. They say, 'What gets measured, gets improved," Fraser said.
"That probably would have been the last place I would have even thought they can get more information about how [the coronavirus] is spread," said Purcellville resident and high school history teacher Jason Lucas. "Whatever they can do to get information, to be active, to feel like they’re giving their constituents the belief they are doing everything they can to know the most amount about this virus that they can, I think that’s great."
BioBot says other cities in the D.C. metro area have signed up for COVID-19 sewage testing, but is keeping its customer list confidential.
"So, today, we're in 400 communities. We imagine being able to test up to 75% of the U.S. population," added Ghaeli.