The COVID-19 virus has heavily impacted the nation, San Antonio and the UTSA community this year. Vikram Kapoor is an assistant professor in the Department of Civil and Environmental Engineering at UTSA and part of a research team that found that the coronavirus can be tracked using sewer systems.

When asked how he first came up with his hypothesis, Kapoor says the method of testing sewage water for disease is not new. 

“Scientists have been searching sewage for pathogens for many years, most notably for poliovirus,” Kapoor said. “The idea got attention when it was discovered that about two-thirds of people infected with SARS-CoV-2 excrete the coronavirus in their stool.” 

For his research, Kapoor says a treatment facility can monitor wastewater “for the virus’ RNA using molecular tools.”

Kapoor and his team first started sampling at the San Antonio River Authority’s Salitrillo Wastewater Treatment Plant in May 2020. They have benefited from a $160,000 grant from the CARES act. 

“The grant is helping us to continue wastewater sampling and analysis until the end of the year,” Kapoor said. “We are also expanding the sampling sites to include more treatment plants with the help of this funding.”     

According to Kapoor, there are still many more challenges that need to be worked out before this technique can be readily applied for virus surveillance. 

“There are a variety of issues with detection limits, getting composite samples from wastewater treatment facilities and of course just the fact that many sick people might not excrete viral RNA for us to detect,” Kapoor said. “A negative wastewater result does not in fact mean that zero people in the area have the coronavirus, so wastewater surveillance is subtly different from a clinical diagnosis tool.”     

Kapoor explained how the testing process works. 

“Infected individuals excrete the virus, which gets flushed down the toilet or washed down the drain,” Kapoor said. “The virus — or fragments of its genes — then travel through a community’s sewage system to a treatment plant, where careful sampling can detect its presence. Most methods involve concentrating the wastewater sample so that we are able to detect the viral RNA, for instance by filtering the samples on a membrane. Then, we extract the total RNA from the filter and use a molecular technique called droplet digital polymerase chain reaction (ddPCR) to quantify the viral RNA in the sample.”

Graduate students and postdoctoral researchers from UTSA have helped this research in areas “from sample collection to molecular analysis.” The research has three goals: First, to detect whether the virus is present or not in the samples; second, monitoring for trends; and third, directly applying the discovered measurements of trends to estimate the number of infected individuals in the community. 

Kapoor is already looking for ways this could help San Antonio. 

“The overall vision is that wastewater monitoring could inform all sorts of public health intervention and disease surveillance programs,” Kapoor said. “It could complement clinical surveillance, which often lags behind the true disease level in the community.”