The virus raged around the world, terrifying the populace with its seemingly random strikes.

Most victims showed no signs of the disease or had mild complaints. Just a fever or fatigue, maybe. Others suffered more serious symptoms, with some becoming unable to breathe on their own. A not insignificant number of patients developed long-term disabilities. In extreme cases, people died.

While the planet waited for a vaccine, governments responded by imposing social-distancing rules as the disease hit again and again in seasonal waves. Events were canceled. City pools were closed. Families avoided public parks.

And epidemiologists in the United States monitored the outbreak by surveilling wastewater – including the untreated waste from household drains and toilets – for evidence of the disease at large.

Preserving samples
for posterity

Taking samples from a community’s wastewater can help public-health authorities track and monitor disease practically in real time. But researchers from the University of Basel in Switzerland and Rockefeller University in the United States are suggesting another use for the technology: creating biological time capsules. Read more›››

In a paper in BMC Infectious Diseases, David S. Thaler and Thomas P. Sakmar suggest systematically storing biological material taken from sewage to create an archive of sorts in case today’s viruses become important in the future.

Preserved “before” and “after” samples could also help scientists studying, for example, a pathogen’s arrival in a city or on a cruise ship, the researchers note.

“There is so much great work throughout the world on monitoring wastewaters for immediate information. If only you could ‘go back in time,’ then it might become possible to learn more about the origin and early spread of infections,” Thaler tells KUST Review. “Also it might help (researchers) understand how effective mitigation measures were. The limiting factor right now is to work out simple, inexpensive ways to obtain and store many samples. Historical records help with understanding so many things.”

Other biological repositories and records include living cell and tissue collections, eDNA and material from museums and medical facilities.‹‹‹ Read less

No, we’re not talking about COVID-19. We’re talking about poliovirus, the pathogen that killed or paralyzed about a half-million people a year worldwide during its peak in the 1940s and ’50s. But the same basic wastewater-surveillance techniques epidemiologists used in Midcentury America to track polio outbreaks would prove useful again some 70 years later when the coronavirus pandemic put an unready world into lockdown.

Of course, the techniques have become much more sophisticated since the 1940s, but the basics remain the same: Take small samples of fecal matter from sewer systems, examine the material in a lab and determine what sorts of pathogens have taken root in a community — whether that community is a city, a neighborhood or even a prison.

REAL-TIME SNAPSHOT

Advances — most notably the emergence in the 1990s of polymerase chain reaction (PCR) to amplify sections of DNA from a small sample — have improved the process, enabling public-health authorities to track disease in a way that might prove difficult by other means because of lag time between tests and results or because the disease is frequently under-reported. This could be because the disease is often asymptomatic or has the kind of nonspecific symptoms that patients are unlikely to report until they get serious, such as influenza, gastroenteritis or, yes, polio. Or the patient or doctor may simply choose not to test.

In those cases, testing sewage removes those barriers from the equation and takes an anonymous, nearly real-time snapshot of a community’s health in a way that would be difficult to achieve by individually testing its members.

“You would have to sequence a ton of clinical or nasal swabs to get that level of resolution,” says Smruthi Karthikeyan, a postdoctoral scholar and lead author of a recent study on using genomic surveillance to detect SARS-CoV-2 infections during 10 months of the pandemic at the University of California, San Diego, in an interview with the Journal of the American Medical Association.

It also gives health authorities an early alert when a new disease is taking a foothold in a community, perhaps warning of an incipient need for more hospital beds or other measures.

In fact, this is what happened when a collaboration between researchers from Stanford University, Emory University and Alphabet company Verily analyzed sewage from 41 communities in 10 U.S. states to track a newly emergent monkeypox in 2022.

“We have now detected monkeypox DNA in sewersheds before any cases were reported in those counties,” Bradley White, a senior staff scientist at Verily, tells Time magazine.

DATA WITHOUT BIASES

Another advantage: It doesn’t have the problem of biases often affecting traditional public-health data.

“A major benefit of wastewater monitoring is that it can capture the health markers of anybody who lives or works in a building connected to a centralized sewer system,” says Aparna Keshaviah, an expert in wastewater epidemiology and principal researcher at Mathematica, a U.S.-based organization that uses data, analytics and technology to address social challenges.

“In other words,” she tells KUST Review, “it doesn’t rely on people to have the will or means for a health-care visit to be counted, and so is less biased than traditional public health data.”

The surveillance can also let those same health authorities know when the storm has passed and it’s time to end such restrictions as social distancing, mask regulations and quarantines.

And it works. Many studies have shown that wastewater monitoring provides an accurate view of disease in a community. COVID-era studies also confirmed that the technique was an accurate reflection of the coronavirus’ course in a community.

A Dutch group, for example, began monitoring the sewage from seven cities and an airport in February 2020, detecting the presence of COVID-19 at five sites just about a week after the first case was reported in the country. Meanwhile, Karthikeyan’s work at UC-San Diego found variants of concern up to two weeks before they turned up in clinical tests.

USED AROUND THE WORLD

At least 55 countries worldwide use wastewater monitoring to track COVID-19. In 2020, the United States launched its National Wastewater Surveillance System, working with health systems across the country to track disease and trends. And in 2021, the European Union asked all member states to put in place wastewater monitoring to track COVID-19 and its variants, with the EU’s Environment Commissioner Virginijus Sinkevičius telling EURACTIV.com that the process is a “cost-effective, rapid and reliable complementary tool.”

Another benefit: The testing can immediately assist more than researchers looking to track disease. It can also provide a real-time heads-up to members of the community.

“In communities where the wastewater data are made public in a timely fashion (for example, when public-facing wastewater dashboards are updated weekly with new information on wastewater viral levels), individuals can monitor the data to gauge their risk of exposure to COVID-19 and make more informed decisions about what risks they’re willing to take,” Keshaviah says.

The testing, however, relies on the existence of robust wastewater-treatment and -disposal systems. Most wastewater monitoring, therefore, occurs in more economically advanced nations.

This leaves low- and lower-middle-income countries unable to take full advantage of the public-health benefits. According to Utrecht University’s Edward R. Jones and his team in a paper published in Earth System Science Data, most wastewater isn’t even collected in those countries.

COMMUNICATION IS KEY

Another problem: Information is only as good as the communication network it relies on.

“During this pandemic, many communities launched local or regional wastewater monitoring for the SARS-CoV-2 virus that causes COVID-19. But based on results from a global wastewater survey we recently conducted in partnership with the Rockefeller Foundation and the United Kingdom Health Security Agency, the resulting data have not always been shared in a timely fashion with neighboring communities, let alone with other countries across the globe,” Mathematica’s Keshaviah tells KUST Review.

“In today’s interconnected world, international travel is 56 times more common than it was in 1950, and so one country’s local infectious disease outbreak can quickly become a global pandemic,” she says. “If we’re to have any chance at getting an early warning of the next new health threat before it explodes into another pandemic, we need global leadership to coalesce the many individual wastewater initiatives that now exist into a multi-nodal, unified disease-monitoring network that’s always on and always communicating.”

CAPTION: Khalifa University

Wastewater monitoring can be used for more than detecting disease. It has also been used to detect the use of illicit drugs in a community.

The European Monitoring Centre for Drugs and Drug Addiction used data from studies conducted since 2011 to plot the prevalence of such substances as cocaine, methamphetamines and cannabis in 80 European cities and towns, revealing what it called distinct geographical and temporal patterns.

CONCERNS ABOUT PRIVACY

Surveillance could perhaps do more. And that raises privacy and civil-liberties concerns.

A paper from academics in law and medical programs at Wayne State University and the University of Maryland that was published in the Journal of Law and the Biosciences notes that there are legal and ethical implications to consider, such as governments using evidence of a pathogen in public wastewater to justify additional screenings of certain neighborhoods or impose penalties on those who refuse to cooperate.

Mathematica’s Keshaviah sees a potential for concern that small communities and individuals might be identifiable via wastewater monitoring, but also a solution:
“When wastewater data are collected at centralized wastewater treatment plants that serve many hundreds, thousands or millions of people (which is the most cost-effective way to detect novel threats), there’s little chance that the data could be identifying. However, when monitoring occurs at the neighborhood or facility level, when the threat being monitored is quite rare, or when wastewater data are combined with other data sources, the risk of identifying individuals can increase.

“That said, just as with medical data, wastewater data can be blinded before they’re shared, so that individuals or communities are not stigmatized by the results. The data can be collected at a localized level to inform decision making, but shared in such a way that obscures the precise communities represented by the data, to preserve privacy,” she says.

In the meantime, wastewater monitoring continues to help public-health authorities track disease via the public sewers.

In October 2022, researchers with the U.S. Centers for Disease Control and Prevention and various public-health programs published an article about investigating a potential emerging viral threat in New York City.

They found polio.