IIf the past two years have taught us anything, it’s that testing for viral diseases is complicated. Sometimes tests are hard to get, like in the early days of COVID-19. And even if people have access to the test, they may not feel they need it. People infected with COVID-19 Often has no symptoms And they may not always know how to take the test. Now, with home self-exams available, most people test themselves and don’t report results. With other diseases – such as monkeypoxStigma surrounding the disease and the group most affected can prevent access to testing.
These restrictions hinder the ability of health authorities to learn more about infectious diseases and control their spread. If you can’t spot a problem, you can’t direct resources to help solve it.
Wastewater analysis can help avoid some of these problems. Scientists have tracked COVID-19 through wastewater since early in the pandemic, and now they’re doing the same for monkeypox. A new program led by researchers at Stanford University, Emory University and Verily, a subsidiary of Alphabet Inc. , monitored monkeypox cases by analyzing wastewater from 41 communities in 10 states. So far, they have detected monkeypox virus in 22 of those sites. With monkeypox case numbers continuing to rise across the country, this information is proving to be valuable as clinicians and patients grapple with testing challenges. “We have now detected monkeypox DNA in sewers before any cases were reported in those counties,” says Bradley White, Verily’s chief scientist. The group plans to publish their first findings from their work on monkeypox in preprint soon. Academic and other public health groups work with local sanitation facilities to track the virus, but this program is called Sewagefocuses on getting a national picture of where cases are.
Data is shared publicly on a file website Hosted by Stanford University, the group is sharing its findings with the US Centers for Disease Control and Prevention (CDC).
Because sanitation is made up of thousands of people, it provides an ideal, anonymous method for detecting virus levels in communities. “We pick up cases even if people are asymptomatic,” says Marilyn Wolf, professor of environmental health at Emory and co-principal investigator at WastewaterSCAN. “When there is limited testing capacity, and there is stigma associated with disease, getting a measure of infection at the population level that is not affected by these things is really powerful.”
Another reason sewage is such a complex way to track monkeypox has to do with the fact that it contains liquid residues not only from urine and feces, where the virus can be excreted, but also from saliva and water that drains while people brush their teeth and shower. Because monkeypox virus is active in skin lesions, these secretions are particularly effective means of trapping and detecting the virus.
Researchers have analyzed wastewater for decades, most notably during the 1940s to track polio in the United States. The COVID-19 pandemic has proven beneficial on a large scale. Studies have shown that waste samples generally pick up signs of SARS-CoV-2 infection for up to a week before clinics in the area begin seeing positive cases. It can even detect sewage New variants of SARS-CoV-2—Something a quick test can’t do.
In late 2020, the CDC launched National Wastewater Monitoring System (NWSS), the first federal system of infectious disease tracking The pathogen – in this case, SARS-CoV-2 – is in the wastewater. It is an attempt to standardize the way wastewater is collected, analyzed and interpreted. NWSS now includes data from local programs – such as WastewaterSCAN – and cities with their own tracking systems. New York City’s vital monitoring program, for example, has been testing sewage for signs of SARS-CoV-2 since February, and now 11 hospitals in the group will Start scanning for monkeypox and poliowhich was discovered in New York City wastewater.
When monkeypox cases first began appearing in the United States, researchers at Stanford, Emory and Fairley saw an opportunity to apply a wastewater lens to the disease, especially since monkeypox testing was not widely available. They have been tracking SARS-CoV-2 at a few locations in California through Sewer Corona Virus Alert Network (SCAN) Since November 2020, analyzes have been added for other viruses, including influenza and RSV. When monkeypox cases began spreading around the world, and while access to testing was still limited, they added this virus to their investigation as well and expanded their network to include more locations across the country. Wastewater SCAN was born.
Wolf says the group’s platform to isolate genetic material from microbes made it relatively easy to create the appropriate test for detecting monkeypox virus in mid-June. They targeted a part of the monkeypox genome that was relatively unique, and the probe successfully identified the virus in their lab tests. But, says White, “the first few tests we did on sewage samples didn’t pick up anything.” This was probably due to the low concentration of the virus in the wastewater at that point. While the WastewaterSCAN probe was designed to capture very dilute amounts of virus, at the time of testing, there were a few cases in Northern California. On June 19, WastewaterSCAN began testing samples provided daily from two processing plants in the San Francisco area. The next day, both sites tested positive for monkeypox.
The genetic material of monkeypox virus differs from that of SARS-CoV-2 because it is in the form of DNA, while the COVID-19 virus and all of the group’s previous tests were directed against RNA. But, says White, “DNA is more stable than RNA, so as long as the genetic material is extracted from the sample, we’re pretty confident that if people secrete a virus into wastewater, we’ll eventually find it.”
Scientists say there are still a few important unanswered questions about monkeypox in sewage. They don’t have enough data to say for sure how much sewage water can give health officials more leeway about an increase in cases, compared to screening in clinics and hospitals. They also continue to analyze the data to get a better idea of how much of the virus must be circulating in a community, or how many cases must accumulate in a given area, before their analysis can pick up signs of the virus in sewage. This could give doctors an important start in preparing sufficient numbers of tests, vaccines, and treatments for the disease before cases reach a peak.
The WastewaterSCAN team is now applying what they’ve learned from COVID-19 and monkeypox to explore ways to monitor influenza, RSV, and other seasonal diseases. In the case of RSV, a respiratory infection that often affects children, knowing where cases begin to spread can help doctors treat the most vulnerable children with a monoclonal drug before they are exposed, thus avoiding them from developing potentially serious illness.
Wolf says the key to having such a national system is coordination between partners who share their findings. “Having a network of sites using the same methods of collection and analysis so we can compare the data gives us a national picture of what’s going on,” she says. “We would like to have more federal investment in systems like this.”
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