Wastewater monitoring provides a powerful tool for tracking COVID and other illnesses.

In 2020, experts from the Biomedical Advanced Research and Development Agency (BARDA) and other public health agencies saw a presentation that many at the time considered unrealistic.Several companies have proposed on a regular basis Sample wastewater from sewer Run the processing plant and tests to detect SARS-CoV-2 (the virus that causes COVID-19). People excrete the virus as waste, and companies track the levels of genetic material or RNA in the sewage over time to see if the virus was elevated days or weeks before the patient’s surge. With COVID suggested that you can easily get a glimpse.

“I must say it wasn’t taken seriously [by us] Rick Bright, who oversaw BARDA at the time and is now Senior Vice President of Pandemic Prevention and Response at The Rockefeller Foundation, says.Nevertheless Wastewater tracking Used in the past Polio tracking And gastrointestinal illness, which didn’t seem like a priority during an ongoing pandemic, he says.

Then, in November last year, researchers from several universities and the US Centers for Disease Control and Prevention announced that the Omicron variant in wastewater from Northern California, Houston, New York City, and elsewhere in the United States was publicly announced. Health authorities may take stricter precautions, such as mandating masks, and give them valuable lead time to direct inspections and other resources to the community. Such information also allows authorities to lift restrictions when cases begin to diminish. “Suddenly the light came on,” says Bright. “Instead of a kneeling reaction, we were able to develop evidence-based policies.”

On February 4, CDC announced the addition Wastewater component To that COVID data tracker. For the first time, it has become possible to directly compare wastewater data from different states. More than 400 sites nationwide are already enrolled in the CDC program, with more sites continuing to participate each week.

The goal of Amy Kirby, Program Leader of the CDC’s National Wastewater Surveillance System, is to provide an unbiased way to track COVIDs, which is more comprehensive than monitoring infected cases. By analyzing wastewater, it is possible to detect asymptomatic cases, cases in which a person is infected but the test is not positive, and cases detected by a home test for which no results have been reported to the CDC.

Performing a polymerase chain reaction (PCR) test (the most accurate method for detecting SARS-CoV-2) on wastewater samples is not technically difficult, but until recently, infrastructure setup was required. It didn’t seem worth the effort and money, says Kirby. “COVID really changed the math and made it a good investment,” she says. The CDC is also spending $ 233 million to enhance state and municipal surveillance to track SARS-CoV-2 along with antimicrobial-resistant bacteria, influenza, and fungi. Candida auris Kirby says there is also food poisoning such as norovirus and salmonella.

Environmental engineers working on wastewater pathogens, such as Colleen Naughton at the University of California, Merced, are pleased to see the technology in widespread use. “It’s definitely exploding all over the world,” says Norton. In September 2020, her group launched a database called COVIDPoops19 to create maps. SARS-CoV-2 Wastewater monitoring sites around the world.. Since then, the number of such databases has more than tripled. The state or federal government performs much of the tracking work and publishes the data on its own online dashboard.

Currently, most of these efforts use PCR to amplify virus fragments and look for traces of SARS-CoV-2 that determine the total amount of virus present in the area compared to the past few weeks or days. I am. However, some teams are working on more advanced techniques for genetically sequencing long sections of the virus. This approach allows researchers to determine not only what new mutations have occurred, but whether they have all occurred in the same virus or in a mixture of different strains.

“What I like is that you can start seeing the understory vegetation of the viral rainforest,” says Christopher Mason, a geneticist at Weill Medical College in New York City. New mutants increase the threat to humans by monitoring all mutants in wastewater, rather than detecting only when major mutants such as Delta and Omicron begin to affect humans. Earlier, he says, scientists can see how SARS-CoV-2 is evolving.

In the study described in Nature Communications Last month, John Denny at the Queens College and Graduate Center at City University of New York and Mark Johnson at the University of Missouri used detailed sequencing techniques. Detect new forms or strains of SARS-CoV-2 in New York City wastewater.. These strains, which have not yet been detected in humans, contain mutations that allow them to infect rodents and may have entered the water system through the ubiquitous brown rat in New York. It suggests that. This finding supports concerns that animals may function as a reservoir of COVID, and tracking the infection may prove important for plans to control the pandemic. However, Johnson and Denny say there may be other explanations: the pedigree may have evolved in immunocompromised individuals who had long-term COVID, giving the virus time to evolve.

Despite the valuable lead time that wastewater tracking can provide, it cannot replace patient surveillance efforts, Johnson says. His team detected Omicron in New York City wastewater more than a week before the first case appeared in a U.S. patient, but “without knowing it was Omicron, it didn’t look unusual. Let’s do it, “he says. In other words, wastewater sequencing can provide so much data that meaningful variants can be lost if the researcher does not have more information about their clinical significance. ..

Wastewater monitoring has other significant drawbacks. Cases of COVID are so prevalent today that the virus is easy to detect in wastewater, but less common infections that cause hepatitis and food poisoning can be more difficult to detect. I have. Also, different public health centers use different sampling techniques and record data in different ways, which can make it difficult to compare them. Scientists at both the CDC and the Rockefeller Foundation want to develop ways to standardize wastewater data from different communities so that they can be compared more easily with each other and with patient cases in each community. I am.

Privacy is also a concern. Taking samples from urban sewers and treatment facilities is essentially anonymous, but monitoring small spills from college dormitories, for example, may seem invasive. Megan Diamond, a Rockefeller Foundation researcher working with Bright to develop a database of COVID wastewater data, works with the community to build trust and educate people about what wastewater tracking can and cannot do. Is essential.

Sequencing technology can also be expensive. In addition, more than 85% of tracking sites are located in high-income countries, according to COVID Loops 19 data analyzed by the World Bank. Also, tracking efforts are not comprehensive in the United States, as researchers have easy access to public sewer systems and miss about 20% of US households using septic tanks. Norton, the Rockefeller Foundation team, and others are trying to expand their technology and surveillance databases to developing countries. In developing countries, unbiased sampling methods are even more valuable due to the lack of clinics and less patient monitoring. “We need a way to monitor, not just the luxury of the first world,” says Bright.