In addition to viruses, wastewater analysis can also be used to detect the presence of chemical substances such as opioids
Wastewater surveillance and analysis continues to be a useful tool for detecting the prevalence of viruses such as SARS-CoV-2, influenza, and respiratory syncytial virus (RSV) in a community. Perhaps more importantly, wastewater surveillance can fill in gaps where clinical laboratory testing data may be days or weeks behind the true spread of viral infections.
One sign of the value of testing wastewater for infectious diseases is the fact that government officials are financing a continuing program of wastewater testing. In September, the federal Centers for Disease Control and Prevention (CDC) awarded a contract to conduct wastewater surveillance/analysis worth millions of dollars to Verily Life Sciences, a Google company, rather than renewing its contract with Biobot Analytics, which had been doing the work since 2020. One interesting twist in the award of this contract is how an ensuing dispute pulled the plug on a significant portion of the wastewater analysis in this country.
In their September Morbidity and Mortality Weekly Report (MMWR), the CDC highlighted a CDC study during which wastewater samples were taken from 40 wastewater treatment plants located in Wisconsin’s three largest cities. The samples were collected weekly and tested for influenza and RSV. The findings were then compared with data regarding emergency department (ED) visits for those diseases.
The CDC found that higher detections of flu and RSV were associated with higher rates of ED visits for both illnesses. The study also suggests that wastewater might detect the spread of these viruses earlier than ED visit data alone.
“During the COVID-19 pandemic, wastewater surveillance for SARS-CoV-2 provided valuable insight into community incidence of COVID-19,” said Peter DeJonge, PhD (above), a CDC Career Epidemiology Field Officer, in an interview with Infectious Disease Special Edition. “[The CDC’s] report supports the idea that wastewater surveillance also has the potential to serve as a useful method with which to track community spread of influenza and RSV.” Local clinical laboratories are also involved in the CDC’s wastewater surveillance programs. (Photo copyright: CDC.)
Keeping Communities Informed about Spread of Viral Infections
The CDC’s study was conducted from August 2022 to March 2023. The wastewater samples from all three cities tested positive for the viruses in advance of increases in ED visits. After the ED visits for those viruses had subsided, the viral material remained in sewersheds for up to three months.
“Both influenza and RSV can cause substantial amounts of illness, hospitalization, and even death during annual epidemics, which often occur during winter months in the US,” Peter DeJonge, PhD, a CDC Career Epidemiology Field Officer assigned to the Chicago Department of Public Health, told Infectious Disease Special Edition (IDSE). “Clinical providers and public health officials benefit from surveillance data to understand when and where these diseases are spreading in a community each year. This type of data can help prepare clinics [and clinical laboratories] for anticipated cases, tailor public health messaging, and encourage timely vaccination.”
“The collective burden from these respiratory viruses is staggering. With these viruses circulating simultaneously and potentially shifting in seasonality and severity, communities must be able to understand the full impact of each of these illnesses to inform awareness and public health responses that can prevent infections, hospitalizations, and even deaths,” said Mariana Matus, PhD, CEO and cofounder of Biobot Analytics, in an August press release announcing the launch of a “Respiratory Illnesses Panel” that will monitor wastewater for Influenzas A and B (seasonal flu), Respiratory Syncytial Virus (RSV), and SARS-CoV-2 (COVID-19).
“Traditional testing methods for these illnesses do not provide a comprehensive picture of the number of people infected due to inaccurate reporting, as well as asymptomatic or misdiagnosed cases,” Matus continued. “By monitoring wastewater concurrently for influenza, RSV, and SARS-CoV-2, we can fill in these gaps and provide important information to communities.”
CDC Moves to Change Wastewater Surveillance Contractor Mid-stream
As new variants of SARS-CoV-2 emerge, a recent contract dispute may be the cause of a time delay in efforts to perform wastewater surveillance for the disease, as well as for other viral infections, according to Politico.
The CDC’s move to replace Biobot Analytics with Verily Life Sciences to do wastewater surveillance has led to Biobot filing a protest with the Government Accountability Office (GAO).
According to World Socialist Web Site (WSWS), “The scope of the [Biobot] contract [to provide extended data for the public health agency’s National Wastewater Surveillance System (NWSS)] included data from more than 400 locations from over 250 counties across the entire United States, covering 60 million people. On top of this, Biobot also conducted genomic sequencing to identify the latest variants in circulation.”
About one quarter of the wastewater testing sites in the country have been shut down due to Biobot’s contract being suspended in September. The remaining 1,200 sites that are not covered under the original contract will continue wastewater testing, Politico reported.
The GAO hopes to have a decision on the contract dispute in January. Verily says it is ready to proceed with testing in all locations and already has its infrastructure in place.
“We are committed to working with the CDC to advance the goals of the … testing program, initiate testing on the samples already delivered when allowed to resume work, and make wastewater data available as quickly as possible,” Bradley White, PhD, Principal Scientist/Director at Verily, told Politico.
Under the terms of Verily’s contract, the company will collect samples from wastewater treatment centers cross the county and analyze the samples for COVID-19 and the mpox (monkey pox) virus.
This contract marks the first agreement between the CDC and Verily.
The CDC has not disclosed why it decided to change contractors, but it is probable that cost may have been played a role in the decision. Verily’s contract is for $38 million over the course of five years and Biobot’s most recent contract was for around $31 million for a period of less than 18 months, Politico reported.
In a LinkedIn post, Matus reported that Biobot had already laid off 35% of its staff due to the contract decision by the CDC.
Competition in Wastewater Surveillance Market
When seeking viruses in wastewater, scientists use gene-based detection methods to locate and amplify genetic signs of pathogens. But public health officials are just beginning to tap into the potential opportunities that may exist in the analysis of data present in wastewater.
Wastewater surveillance is also being looked at as a way to combat America’s opioid epidemic.
“Wastewater surveillance is becoming more mature and more mainstream month after month, year over year,” Matus told Time.
Thus, regardless of which companies end up working with the CDC, it appears that wastewater surveillance and analysis, which requires a great deal of clinical laboratory testing, will continue to help fight the spread of deadly viral infections, as well as possibly the nation’s drug epidemic.
Researchers surprised that process designed to detect SARS-CoV-2 also identifies monkeypox in wastewater
Early information about an outbreak in a geographical region can inform local clinical laboratories as to which infectious agents and variants they are likely to see when testing patients who have symptoms. To that end, wastewater testing has become a rich source of early clues as to where COVID-19 outbreaks are spreading and how new variants of the coronavirus are emerging.
Ongoing advances in genetic sequencing and digital technologies are making it feasible to test wastewater for infectious agents in ways that were once too time-consuming, too expensive, or simply impossible.
“Before wastewater sequencing, the only way to do this was through clinical testing, which is not feasible at large scale, especially in areas with limited resources, public participation, or the capacity to do sufficient testing and sequencing,” said Knight in a UCSD press release. “We’ve shown that wastewater sequencing can successfully track regional infection dynamics with fewer limitations and biases than clinical testing to the benefit of almost any community.” (Photo copyright: UC San Diego News.)
Same Process, Different Virus
Following August’s declaration of a state of emergency by California, San Diego County, and the federal government, UCSD researchers added monkeypox surveillance to UCSD’s existing wastewater surveillance program.
“It’s the same process as SARS-CoV-2 qPCR monitoring, except that we have been testing for a different virus. Monkeypox is a DNA virus, so it is a bit of a surprise that our process optimized for SARS-CoV-2, which is an RNA virus, works so well,” said Rob Knight, PhD, Professor of Pediatrics and Computer Science and Engineering at UCSD and one of the lead authors of the study in the press release.
According to the press release, RNA sequencing from wastewater has two specific benefits:
It avoids the potential of clinical testing biases, and
It can track changes in the prevalence of SARS-CoV-2 variants over time.
In 2020, at the height of the COVID-19 pandemic, scientists from the University of California San Diego and Scripps Research looked into genetic sequencing of wastewater. They wanted to see if it would provide insights into levels and variants of the SARS-CoV-2 within a specific community.
Individuals who have COVID-19 shed the virus in their stool.
The UCSD/Scripps researchers deployed commercial auto-sampling robots to collect wastewater samples at the main UCSD campus. They analyzed the samples for levels of SARS-CoV-2 RNA at the Expedited COVID-19 Identification Environment (EXCITE) lab at UCSD. After the success of the program on the campus, they extended their research to include other facilities and communities in the San Diego area.
“The coronavirus will continue to spread and evolve, which makes it imperative for public health that we detect new variants early enough to mitigate consequences,” said Knight in a July press release announcing the publication of their study in the journal Nature, titled, “Wastewater Sequencing Reveals Early Cryptic SARS-CoV-2 Variant Transmission.”
Detecting Pathogens Weeks Earlier than Traditional Clinical Laboratory Testing
In July, the scientists successfully determined the genetic mixture of SARS-CoV-2 variants present in wastewater samples by examining just two teaspoons of raw sewage. They found they could accurately identify new variants 14 days before traditional clinical laboratory testing. They detected the presence of the Omicron variant 11 days before it was first reported clinically in the community.
During the study, the team collected and analyzed 21,383 sewage samples, with most of those samples (19,944) being taken from the UCSD campus. They performed genomic sequencing on 600 of the samples and compared them to genomes obtained from clinical swabs. They also compared 31,149 genomes from clinical genomic surveillance to 837 wastewater samples taken from the community.
The scientists distinguished specific viral lineages present in the samples by sequencing the viruses’ complete set of genetic instructions. Mutational differences between the various SARS-CoV-2 variants can be minute and subtle, but also have notable biological deviations.
“Nothing like this had been done before. Sampling and detection efforts began modestly but grew steadily with increased research capacity and experience. Currently, we’re monitoring almost 350 buildings on campus,” said UCSD’s Chancellor Pradeep Khosla, PhD, in the July press release.
“The wastewater program was an essential element of UC San Diego Health’s response to the COVID pandemic,” said Robert Schooley, MD, Infectious Disease Specialist at UC San Diego Health, in the press release. Schooley is also a professor at UCSD School of Medicine, and one of the authors of the study.
“It provided us with real-time intelligence about locations on campus where virus activity was ongoing,” he added. “Wastewater sampling essentially allowed us to ‘swab the noses’ of every person upstream from the collector every day and to use that information to concentrate viral detection efforts at the individual level.”
Monkeypox Added to UCSD Wastewater Surveillance
In August, UCSD officially added the surveillance of the monkeypox virus to their ongoing wastewater surveillance program. A month earlier, the researchers had discerned 10,565.54 viral copies per liter of wastewater. They observed the levels fluctuating and increasing.
On August 2, the scientists detected 189,309.81 viral copies per liter of wastewater. However, it is not yet clear if the monitoring of monkeypox viral loads in wastewater will enable the researchers to accurately predict future infections or case rates.
“We don’t yet know if the data will anticipate case surges like with COVID,” Knight said in the August UCSD press release announcing the addition of monkeypox to the surveillance program. “It depends on when the virus is shed from the body relative to how bad the symptoms are that cause people to seek care. This is, in principle, different for each virus, although in practice wastewater seems to be predictive for multiple viruses.”
Utilization of genetic sequencing of wastewater sampling will continue to develop and improve. “It’s fairly easy to add new pathogens to the process,” said Smruthi Karthikeyan, PhD, an environmental engineer and postdoctoral researcher in Knight’s lab who has overseen wastewater monitoring at UC San Diego. “It’s doable on short notice. We can get more information in the same turnaround time.”
Thus, clinical laboratories engaged in testing programs for COVID-19 may soon see the addition of monkeypox to those processes.
Smaller cities and rural towns are finding the NWSS a useful early warning tool for tracking COVID-19 in their communities
In a move that mirrors similar programs around the world, the federal Centers for Disease Control and Prevention (CDC) now monitors sewage nationwide and records levels of SARS-CoV-2 in an effort to prevent new outbreaks of COVID-19 and spot any new variants of the coronavirus.
Advances in gene sequencing technologies are enabling the CDC’s National Wastewater Surveillance System (NWSS), and in many communities, clinical laboratories and health system laboratories have worked with local health authorities to test wastewater since onset of the pandemic.
“What started as a grassroots effort by academic researchers and wastewater utilities has quickly become a nationwide surveillance system with more than 34,000 samples collected representing approximately 53 million Americans,” noted epidemiologist Amy Kirby, PhD (above) during the telebriefing.
Kirby is a Senior Service Fellow in the Waterborne Disease Prevention Branch at the CDC.
“Currently, CDC is supporting 37 states, four cities, and two territories to help develop wastewater surveillance systems in their communities. More than 400 testing sites around the country have already begun their wastewater surveillance efforts,” she added.
“Estimates suggests between 40% and 80% of people with COVID-19 shed viral RNA in their feces, making wastewater and sewage an important opportunity for monitoring the spread of infection,” said epidemiologist Amy Kirby, PhD (above), a Senior Service Fellow in the Waterborne Disease Prevention Branch at the CDC. The NWSS’ findings could enable public health officials to better allocate mobile clinical laboratory testing and COVID-19 vaccination sites around the country. This would be especially beneficial in rural and underserved healthcare populations. (Photo copyright: Center for Global Safe Water, Sanitation, and Hygiene.)
Genetic Sequencing Enables Tracking of Virus and Bacteria
At the time of the telebriefing, the federal agency anticipated having an additional 250 sites online within a few weeks and even more sites added within the coming months. Many of the participating sites are sequencing the genes of their biological samples and reporting that data to the CDC.
“So, we’ve seen from very early days in the pandemic that rates of detection in wastewater correlate very well with other clinical indicators, like pace rates and hospitalization and test positivity,” Kirby stated. “That data continues to come in and it continues to be a very solid indicator of what’s going on in the community.”
Wastewater, also referred to as sewage, includes water from toilets, showers, and sinks that may contain human fecal matter and water from rain and industrial sources. To use the CDC’s wastewater surveillance system:
Wastewater is collected from a community area served by the surveillance system as it flows into a local water treatment plant.
Collected samples are sent to an environmental or public health laboratory where they are tested for SARS-CoV-2.
Health departments submit the testing data to the CDC through the online NWSS Data Collection and Integration for Public Health Event Response (DCIPHER) portal.
The DCIPHER system then analyzes the data and reports the results back to the health department for use in their COVID-19 response.
Beginning in February 2022, members of the public can view the results of collected data online through the CDC’s COVID Data Tracker.
Wastewater Sampling Is a ‘Critical Early Warning System’
According to the CDC NWSS website, there are many advantages to using wastewater surveillance in the fight against COVID-19, including:
Wastewater can capture the presence of the virus shed by people both with and without symptoms.
Health officials can determine if infections are increasing or decreasing within a certain monitoring site.
Wastewater surveillance does not depend on people having access to healthcare or the availability of COVID-19 testing.
It is possible to implement wastewater surveillance in many communities as nearly 80% of the US population are served by municipal wastewater collection systems.
“These built-in advantages can inform important public health decisions, such as where to allocate mobile testing and vaccination sites,” Kirby said. “Public health agencies have also used wastewater data to forecast changes in hospital utilization, providing additional time to mobilize resources and preparation for increasing cases.”
The wastewater sampling represents a critical early warning system for COVID-19 surges and variants, and the CDC hopes this type of sampling and research can be utilized in the future for other infectious diseases.
“Wastewater surveillance can be applicable to a wide variety of health concerns. And so, we are working to expand the National Wastewater Surveillance platform to use it for gathering data on other pathogens, and we expect that work to commence by the end of this year,” Kirby said. “Our targets include antibiotic resistance, foodborne infections like E. Coli, salmonella, norovirus, influenza, and the emerging fungal pathogen Candida Auris.”
Critical Surveillance Tool for Microbiology Laboratories
Independent of the nation’s network of public health laboratories, expansion of this program may give microbiology and clinical laboratories in smaller cities and rural towns an opportunity to test wastewater specimens in support of local wastewater monitoring programs.
As the CDC develops this surveillance network into a more formal program, microbiology labs may find it useful to learn which infectious diseases are showing up in their localities, often days or weeks before any patients test positive for the same infectious agents.
That would give pathologists and clinical laboratory leaders an early warning to be on the alert for positive test results of infectious diseases that wastewater monitoring has confirmed exist in the community.
Though not a replacement for clinical laboratory testing, the CDC says the surveillance system will help slow spread of COVID-19 in vulnerable communities
Clinical laboratory testing for COVID-19 is receiving an ally. In mid-August, the Centers for Disease Control and Prevention (CDC) and the US Department of Health and Human Services (HHS) announced they were initiating a National Wastewater Surveillance System (NWSS) in response to the COVID-19 pandemic.
In collaboration with other federal agencies, the NWSS will work with state, local, territorial, and tribal health departments to collect data on wastewater (aka, sewage) samples throughout the United States.
The goal of the NWSS is to detect SARS-CoV-2, the coronavirus that causes COVID-19, before it spreads by detecting traces of it in local sewer systems. The level of the virus detected in wastewater can be a leading indicator of a worsening outbreak in a community, according to a CDC statement.
“Quantitative SARS-CoV-2 measurements in untreated sewage can provide information on changes in total COVID-19 infection in the community contributing to that wastewater treatment plant,” noted the CDC.
People infected with the coronavirus discard traces of it—whether they are symptomatic or asymptomatic—and levels of the virus in untreated sewage can provide scientists with information about the degree of outbreak in specific areas.
The NWSS will not include or monitor homes that use septic tanks or entities with decentralized systems that treat their own waste, such as hospitals, universities, and prisons.
Not a Replacement for Clinical Laboratory Testing
The CDC stressed that sewage testing is not meant to replace clinical laboratory testing, but it can be a valuable tool in communities where COVID-19 tests are underutilized or unavailable. Wastewater testing, CDC noted in its statement, could have an enormous reach as 80% of households in the US are connected to a municipal sewage system.
The CDC is not actively taking samples from wastewater, but relying on local partners to take samples, test them, and enter data into the NWSS portal for the purpose of summarizing and interpreting for public health action.
The agency predicts that participation in a national database will ensure data comparability across separate jurisdictions.
Could Testing Raw Sewage Be More Effective than Contact Tracing for Tracking COVID-19 Outbreaks?
A Yale University study published in Nature Biotechnology, titled, “Measurement of SARS-CoV-2 RNA in Wastewater Tracks Community Infection Dynamics,” detected SARS-CoV-2 concentrations in sewage sludge in New Haven, Conn., over a 10-week period earlier this year. The results of the study “show the utility of viral RNA monitoring in municipal wastewater for SARS-CoV-2 infection surveillance at a population-wide level,” the study authors noted.
The published study states that “SARS-CoV-2 RNA was detected throughout the more than 10-week study and, when adjusted for time lags, tracked the rise and fall of cases seen in SARS-CoV-2 clinical test results and local COVID-19 hospital admissions. Relative to these indicators, SARS-CoV-2 RNA concentrations in sludge were 0–2 [days] ahead of SARS-CoV-2 positive test results by date of specimen collection, 0–2 [days] ahead of the percentage of positive tests by date of specimen collection, 1–4 [days] ahead of local hospital admissions and 6–8 [days] ahead of SARS-CoV-2 positive test results by reporting date.”
The Yale researchers concluded, “Our results demonstrate that measurement of SARS-CoV-2 RNA concentrations in primary sludge provides an approach to estimate changes in COVID-19 prevalence on a population level. Sludge results were not a leading indicator compared to positive test results or percentage of positive tests by date of specimen collection. However, they led hospitalizations by 1–4 [days] and test results by report date by ~1 week. Thus, in communities where test reporting is delayed, sludge results, if analyzed and reported on the same day as sampling, can provide substantial advance notice of infection dynamics.”
Jordan Peccia, Jr., PhD (above), Professor of Chemical and Environmental Engineering at the Yale School of Engineering and Applied Science, and study author, told NBC News, “There’s still a lot more to do. We’re one of the earlier groups to have developed a robust relationship between wastewater and coronavirus cases, but this is just a first step.” He added, “It doesn’t replace contact tracing. [But] if we know a little bit ahead of time, we can raise the alarm.” (Photo copyright: Yale University.)
Sewage Testing for COVID-19 Around the World
Sewage testing can provide data to complement other collected information about COVID-19 and steer public health decision-making. However, the CDC notes that “it is not possible to reliably and accurately predict the number of infected individuals in a community based on sewage testing” and that “more data on fecal shedding by infected individuals over the course of disease are needed to better understand the limits of detection.”
Nevertheless, some experts have leaned heavily on sewage sample testing for their conclusions about the origination of the coronavirus. In August, Dark Daily reported on a theory based on finding remnants of SARS-CoV-2 in sewage systems that suggested the virus may not have originated in Wuhan, China. Analysis of sewage samples in Italy, Spain, and Brazil indicated the virus was present in those countries before the disease was known to exist outside of China. The controversy over these findings has motivated virologists to expand wastewater testing.
The creation of the NWSS by the CDC validates growing interest in new methods of testing for infectious disease. Lower cost, faster response time, more automation of genetic sequencing, and improved analytical software has enabled this type of testing to become a useful tool. It would be wise for clinical laboratory managers to monitor the expanded use of new testing technologies for infectious diseases.
