Sewage A Pathway That Demands New Risk Assessments
Scientists are unraveling mysteries surrounding the coronavirus every day. One of the most unusual discoveries deserves further inspection because it represents a double-edged sword in the battle against the pandemic.
First the good news. With swab tests still plagued by capacity issues, inaccuracy, and slow turnaround, testing wastewater for the novel coronavirus’ genetic signature could give communities a faster way to spot outbreaks. Several researchers are looking to wastewater to help fill in the data gap about the prevalence of the pandemic in any given community. The concept has been demonstrated globally and it is gaining momentum. Studies in the U.S. and the Netherlands detected a signal in wastewater about a week before the first clinical case.
“There is real hope that this can be a sensitive, early warning if, as officials ease social distancing measures, COVID-19 begins to spread again,” said Peter Grevatt, CEO of the nonprofit Water Research Foundation.
“Several labs have achieved a proof-of-concept in terms of demonstrating the ability to detect the RNA of the virus in wastewater.”
The stakes are enormous. As states ease social distancing, they need to know if they are reopening too quickly. If they can’t detect a surge of cases until patients show up in emergency rooms, it could be too late to prevent a repeat of this spring, when hospitals in New York City and elsewhere were overwhelmed. If, as many hope, the country makes it through the summer with a “flattened curve” — keeping cases below the number that hospitals can handle — then it will be crucial to be on high alert for any second wave in the fall. Otherwise, the body count will rise and the nation could face another economically crippling shutdown.
“It’s tremendously important to get this right,” Grevatt said. “These are life-and-death questions.” And although more research is needed to figure out if, for instance, the amount of virus in stool and therefore wastewater varies with the severity of disease, “this has the potential to be implemented in the current pandemic.”
Wastewater epidemiology has been used for decades to detect polio in countries where the disease remains endemic and, more recently, to estimate the prevalence of opioid abuse in U.S. communities.
“We know that the coronavirus is shed in the stool, which means it can be collected in sewage systems,” said Megan Murray of the Harvard T.H. Chan School of Public Health. In small studies so far, the detection of the new coronavirus in sewage samples has correlated highly with the arrival of Covid-19 into different communities. It picked up significant amounts of viral material in Boston sewage weeks before cases arrived in March.
In addition to detecting cases sooner, wastewater analysis can also get around the well-known limitations of the swab tests used to detect COVID-19. If the test (which looks for the virus’ genes) is given to 100 infected people, it will miss about 67 if they are four days after infection and 38 if they are on the first day of experiencing symptoms, incorrectly pronouncing them virus-free, Johns Hopkins researchers reported this month in Annals of Internal Medicine.
And although COVID-19 testing in the U.S. has become more available and faster, testing capacity is still nowhere near enough to test everyone every few days, which would be necessary to, for instance, safely reopen schools and workplaces.
“Wastewater offers the opportunity to provide near real-time trend data to evaluate the impact of policy-making,” such as re-opening the economy, said Mariana Matus, CEO and co-founder of Boston-based Biobot Analytics. It can provide “early warning for second waves, and the opportunity to mass-test up to 75% of the U.S. population on a regular basis at a fraction of the cost of clinical testing.”
Getting even a weeklong head start on detecting cases can make a huge difference. If the U.S. had begun imposing social distancing measures one week earlier than it did in March, the death toll by early May would have been 36,000 lower, Columbia University researchers calculated this month. Two weeks earlier would have averted 54,000 deaths.
Biobot is working with about 400 water facilities in 42 states to see if wastewater epidemiology for Covid-19 in the real world can live up to the hopes inspired by early lab tests. When it analyzed wastewater from a Massachusetts plant from March 18 to 25, it found high levels of several telltale SARS-CoV-2 genes.
Biobot is working with about 400 water facilities in 42 states to see if wastewater epidemiology for Covid-19 in the real world can live up to the hopes inspired by early lab tests. When it analyzed wastewater from a Massachusetts plant from March 18 to 25, it found high levels of several telltale SARS-CoV-2 genes. Although that indicated that some number of people had Covid-19, it wasn’t clear how many. Biobot’s analysis “can distinguish between 10 and 100 [cases],” Matus said, “but we are running experiments to get more precise estimates.”
Doing that should be at the top of the research agenda, Grevatt said: “Work is moving in a direction where you may be able to count the cases in a community, but we aren’t there yet.” To get there, scientists must figure out when during the course of infection people shed virus in stool, whether the amount of viral shedding is the same in severe and mild or even asymptomatic cases, and whether the quality of an area’s water — mineral content, industrial effluent, and other components — affect the detection of viral genes.
They’d also like to know where, in the water treatment facility, is the best place to sample for the coronavirus. On Tuesday, scientists in Spain reported a preliminary answer: remnants of virus, including its genes, tend to collect at the “sludge line” in the large settling tanks that separate solids and liquid.
Even if wastewater analysis can’t yet quantify cases, it can detect when their prevalence changes. Scientists in France reported that the rise and fall of confirmed infections in Paris correlated with the amount of virus detected in sewage from March 5 to April 23 (France’s lockdown began on March 17). “Viral genomes could be detected before the beginning of the exponential growth of the epidemic,” the scientists found, and “a marked decrease in [viral RNA] was observed” as case numbers fell.
That and other studies show that “you can track changes like those we’re seeing right now in many communities” as they ease social distancing, Grevatt said. “There are many areas of the country, especially rural ones, that may not even have an infection yet. Wastewater analysis can tell them when they do,” days before someone shows up sick.
Utilities aren’t waiting for every research question to be answered. Oregon’s Clean Water Services, a utility that serves 613,000 people west of Portland, is part of Biobot’s network, sending weekly samples to the company. It is also doing its own research, trying to answer key questions such as how rain affects viral concentration, said Ken Williamson, director of regulatory affairs.
Engineers at the Southern Nevada Water Authority found high levels of five SARS-CoV-2 genes in samples taken around March 9, which lines up with when the state has its first confirmed case, said civil engineer Dan Gerrity of the authority and the University of Nevada Las Vegas. They found a peak in late March and early April, with ups and downs through late May — also mimicking reported case counts.
Hampton Roads Sanitation District in southeastern Virginia started sampling for SARS-CoV-2 on March 11 “to look at trends and estimate what prevalence might look like,” said Jim Pletl, director of water quality for the utility. Cost: $70,000 for an automated RNA extractor, $70,000 for a digital PCR machine, and $100 per sample.
For its inter-lab study, the Water Research Foundation will see if the analyses agree, hoping to come up with best practices that can guide nationwide implementation as soon as this fall. “That,” Grevatt said, “is going to be important for the scientific credibility of this approach.”
The federal government is teaming up with local health departments to begin testing sewage systems for the coronavirus in an effort to catch the virus before it spreads rapidly, according to the U.S. Centers for Disease Control. The CDC in partnership with the U.S. Department of Health and Human Services and other federal government agencies will begin working with state, local, territorial and tribal health departments to collect data on the sewage samples, an effort they call the National Wastewater Surveillance System, or NWSS, according to CDC guidance updated on Monday. The goal is to find traces of the virus shed from people in sewage systems.
CDC is currently developing a portal for state, tribal, local, and territorial health departments to submit wastewater testing data into a national database for use in summarizing and interpreting data for public health action. Participation in a national database will ensure data comparability across jurisdictions.
Data from wastewater testing is not meant to replace existing COVID-19 surveillance systems, but is meant to complement them by providing:
- An efficient pooled community sample.
- Data for communities where timely COVID-19 clinical testing is underutilized or unavailable.
- Data at the sub-county level.
Wastewater testing could potentially have an enormous reach — 80 percent of U.S. households are connected to a municipal sewage system. Depending on the level of virus in the sewage, wastewater testing can also be a leading indicator of a worsening outbreak. People with COVID-19 who show symptoms and those who don’t can discard traces of the virus, allowing scientists to collect data on both types of infection, the CDC says.
Sewage testing has been used to find other diseases, such as polio, and to determine the prevalence of opioid use in some U.S. communities. Some public health experts, including Dr. Ashish Jha, director of the Harvard Global Health Institute, have suggested utilizing sewage testing for Covid-19, saying it’s a cost-effective strategy to track the coronavirus and predict outbreaks.
The CDC is not currently taking samples for testing but is searching for local partners to test and report the data to the agency’s NWSS portal.
Some countries have already started testing wastewater for the coronavirus, including Finland, Germany, and the Netherlands, and water utilities in cities across the U.S. said they would conduct the testing, STAT News reported in late May.
Wastewater (sewage), includes water from household/building use (i.e., toilets, showers, sinks) that can contain human fecal waste, as well as water from non-household sources (i.e., rainwater and industrial use.)
Wastewater can be tested for RNA from the virus that causes COVID-19. While the virus can be shed in the feces (and likely urine) of individuals with COVID-19, there is no information to date that anyone has become sick with COVID-19 because of direct exposure to treated or untreated wastewater. There also is no proof that it has not occurred.
Wastewater surveillance for RNA of the virus that causes COVID-19 is a developing field. Health departments setting up a sewage-based infectious disease surveillance system should consider the following to generate data that is useful for public health response:
- Sewage testing over time can provide trend data that can complement other surveillance data that informs public health decision making. However, at this time, it is not possible to reliably and accurately predict the number of infected individuals in a community based on sewage testing.
- Community-level wastewater surveillance at a treatment plant will not capture homes on a septic-based system.
- Community-level wastewater surveillance at a wastewater treatment plant also will not capture communities or facilities served by decentralized systems, such as prisons, universities, or hospitals that treat their waste.
Low levels of infection in a community may not be captured by sewage surveillance. The lower limits of detection (i.e., the smallest number of people shedding the virus in stool that can still be detected by current testing methods) for sewage surveillance are not yet well understood. More data on fecal shedding by infected individuals over the course of disease are needed to better understand the limits of detection.
“Wastewater carries all of our chemistry,” said Rolf Halden, an environmental health engineer at Arizona State University, who was not involved in either study. “Now we have evidence from two different geographic locations that the virus is detectable, and that’s good.”
The idea to begin testing wastewater for SARS-CoV-2 emerged after recent research revealed that virus particles could be shed through stool and other bodily fluids. Testing begins with collecting sewage samples from local treatment plants, and running them through a process that creates millions of copies of viral RNA to be able to study the pathogen in detail. Another process then looks for specific markers on SARS-CoV-2, to distinguish this particular virus from all the other possible microbes in wastewater samples.
Wastewater has been used in other ways as a public health surveillance tool. Biobot, which was spun out of MIT, has also helped detect opioids in wastewater, as a way to help communities track patterns of drug use and developing public health threats. European countries have long been monitoring the spread of antibiotic resistance through wastewater. And sewage has been used to look for other emerging and known viruses, including polio.
Biobot recently launched a campaign to provide its wastewater sampling services for free to communities across the country. Matus said the campaign has already enrolled 100 treatment plants in 25 states, with the goal of partnering with 10,000 such plants by the end of next month. Others, including Halden at Arizona State, are also involved in coronavirus tracking efforts. Halden leads the Human Health Observatory at ASU, which has over 250 monitoring locations in the U.S. and 350 locations around the world to test wastewater.
Now the bad news. Unfortunately, the United States and many other countries dispose of millions of tons of sewage sludge (biosolids) on land. Many governments are allowing wastewater treatment plants to dump the most toxic portion of their waste streams on open land under the guise of fertilizer. Farms, ranches, parks, schools, golf courses and more have been used as dump sites for more than 30 years.
Even before the arrival of the coronavirus, this reckless practice has been fueling a public health disaster for years. As such, neurodegenerative disease is the fastest-growing cause of death in the world. Alzheimer’s disease, Parkinson’s disease and Creutzfeldt-Jakob disease are the most common forms of prion disease among humans. In other mammals, prion disease is called chronic wasting disease, mad cow disease and other clever names meant to cloak the bigger problem. The scientific name for this pandemic is transmissible spongiform encephalopathy (TSE). The operative word is “transmissible.” As such, sewage and biosolids are spreading the prion pandemic far and wide. It is likely spreading the coronavirus far and wide, where it can contaminate our food, water and air. Answers begin with the truth.
The risk assessments prepared by the U.S. EPA for wastewater treatment, sewage sludge and the land application of biosolids (sewage sludge) are flawed and current practices of recycling this infectious waste are fueling a public health disaster. Many risks are not addressed, including prions, radioactive waste and now the coronavirus. All of these biohazards threaten human health when disposed of improperly. Biosolids are already fueling a global pandemic of neurodegenerative disease. Since the risk assessments on wastewater management are antiquated at best and criminally fraudulent at worst, it’s time to stop these reckless practices in the U.S. and elsewhere around the world. The EPA admitted that the risk assessments are flawed and incomplete in November 2018. The practices are even more reckless today because of the coronavirus, yet they continue.