What if we could predict — and even prevent — a major widespread disease outbreak in San Antonio by monitoring for pathogens in our wastewater?
That idea could become reality in the near future thanks to the work of one Texas A&M University-San Antonio professor and her students, who have launched several projects aimed at detecting and researching new and potentially threatening contaminants in the region’s wastewater.
“With wastewater surveillance, you can detect if … microbes are circulating in an unbiased and non-invasive way and gain information on the population dynamics of infectious diseases,” said Davida Smyth, head researcher and associate professor in the department of natural sciences.
Smyth noted the idea of wastewater surveillance for pathogens became more widespread following the COVID-19 pandemic, with some cities such as Houston and New York utilizing it to detect and study new coronavirus variants.
“We’re taking existing techniques and strategies and using them to look for threats we haven’t encountered yet in our wastewater,” she said. “Then we hope to extend the analysis to include surface and aquifer water to better protect the San Antonio community.”
Earlier this month, Smyth was announced as the possible recipient of a $1 million grant from the U.S. House Appropriations Committee at the bequest of Congressman Joaquin Castro to further her work, which Smyth said would go toward new equipment for the projects.
However, for the grant to come to fruition, the U.S. House of Representatives and U.S. Senate must still pass the FY2025 federal appropriation bills and sign them into law. In 2021, Congress launched the community project funding process to provide an avenue for members to request direct federal funding to support community-driven initiatives in their districts.
“Everything will be spent on the reagents, the kits, the machines, and the displays for sequencing, which is very expensive,” she said.
Smyth said that in addition to helping alert the San Antonio community about viruses and harmful bacteria, the project is also meant to develop a framework for educating students and preparing them to enter the workforce with the skills necessary to detect and respond to these new and emerging threats.
“That’s the big picture goal,” she said. “The project has huge potential as an important public health tool.”
An evolving process
Dressed in a white lab coat and donning a camo-colored ball cap stamped with “U.S. Veteran,” graduate student Blake Meche holds a small vial containing 40 milliliters of raw sewage water he obtained from the San Antonio River Authority at a wastewater plant near Converse.
Working the water into several vials with gloved hands, Meche explains the multiple processes that he and the other students utilize in the lab to isolate a total nucleic acid sample — a biological sample that contains both DNA and RNA — from the water so it can be analyzed.
From isolation, the total nucleic acid samples are then run through different processes to help determine which pathogens are in the water and if there are a lot of these pathogens, explained Smyth. An exact estimate of how many cases of the pathogen there are in a sample though is complicated to discern with the lab’s current equipment, she added.
“It was the major thing I wanted from this funding, was if we can buy a digital PCR machine … it would just be really great,” Smyth said. A digital PCR machine can help give precise quantification to the sought pathogen, she explained. “If we can quantify everything with this absolute quantification … then we don’t have to do any extra work and it would save us so much time and money.”
Exact quantification would allow the monitoring parties to be able to see if a pathogen is a big threat, with multiple ongoing cases or a small threat from say a singular source, Smyth explained. Ideally, the city could then use that data to prevent an outbreak by taking precautionary measures as soon as a disease is found.
“We obviously want to control any kind of spread potentially — hospitals have infection control departments dedicated to this sort of thing,” Meche said. “But they don’t know unless somebody gets sick with it. So with wastewater analysis, we want to be able to at least, you know, have a heads-up.”
The lab is currently on the look out for COVID-19, MRSA, E.Coli and even unknown pathogens via genetic sequencing and other methods, Smyth noted.
“COVID has shown us that we can — this is really creepy, but — we can go up the sewer, and we can track it to household or single toilet, right?” Smyth said. “So you could literally find the source.”
Should the funding come in, Smyth said she hopes to expand their work so that multiple wastewater sites are being sampled and monitored. She would love to perhaps one day work with the city or the San Antonio River Authority to help create a wastewater surveillance team that is on the lookout for San Antonio’s public health, she said.
“We’re not looking at individual people, right?” Smyth said. “We’re getting these really large sample sizes, which is why it’s cheaper and also unbiased.”
