NEW YORK (AP) – One county in Utah repressed an increase in pandemic virus infections in the spring, and another experienced an increase in its rate. Both trends appeared in its wastewater.
Yes, sewer. In the US and Europe, researchers and health officials say they can follow the course of a community outbreak of the new coronavirus by studying waste thrown from their toilets. And that can provide a valuable addition to public health tools, they say.
In Utah, sewage from communities near a Cache County meatpacking plant discovered by 287 infected workers indicated an outbreak several days before it was officially reported. By contrast, Summit County sewage showed a decline after officials imposed anti-virus measures, including asking tourists to stay away from their popular Park City ski area.
Monitoring in April and May was part of a demonstration project, and the results helped persuade state officials to authorize a larger monitoring effort that will include wastewater from 75% of Utah residents, said Erica Gaddis, director of the state’s Water Quality Division.
Utah is far from alone in taking that approach. When the Massachusetts company Biobot said on social media this spring that it would analyze the wastewater for free, it “exploded,” said CEO Marian Martus.
The company acquired 400 wastewater plants in 42 states, representing the waste from about 10% of the US population. The company now charges for its service, Martus said, and it still has hundreds of customers who ship. Regularly sample about half a cup (150 milliliters).
The British, The Italian and Dutch governments have also announced monitoring programs, with the participation of all wastewater treatment plants in the Netherlands. “We can detect the virus anonymously, quickly and on a large scale,” said Dutch Health Minister Hugo de Jonge.
The concept is simple. Studies indicate that the genetic material of the virus can be recovered from the faeces of about half of the patients with COVID-19, the disease caused by the virus. Wastewater analysis looks for that genetic material. The results over time are taken as indications of infection trends in the community that produced the waste. That should even include people who would normally be overlooked because they don’t get tested or may not know they are infected.
The approach can serve as an early warning because it can spot trends several days before community test results appear or people get sick enough to report to a hospital, studies indicate. A Dutch study He found a sewage signal in a city six days before the community reported its first cases.
Wastewater can be used as “a mirror of society,” said Gertjan Medema, a microbiologist at the KWR Water Research Institute in the Netherlands. “Wastewater is more than just a wastewater provider, it is also an information provider.”
Wastewater monitoring is “a very promising tool,” said Vince Hill, head of the water-borne disease prevention arm of the US Centers for Disease Control and Prevention.
The CDC is now working to understand how useful it can be in the United States. “There is a lot to learn,” he said. “We are urgently working on this.”
Wastewater surveillance has long been used to search for outbreaks of the polio virus. With the new app for the pandemic virus, scientists are working to refine their techniques as economies reopen and researchers warn of a possible spike in the disease this fall.
They still don’t have a reliable way to use wastewater to determine how many infected people a community has. Biobot provides estimates, but its calculation method is still being studied and the estimates should not be taken as hard numbers, Martus said.
Researchers in the field are still working to “make sure we have the right science,” said Peter Grevatt, CEO of The Water Research Foundation, which promotes water and wastewater studies to ensure water quality and service.
Among those unknown, experts cite: How does viral shedding in stool vary according to different stages of infection? How can the laboratory results produced by different test methods be compared? And how are samples affected by the characteristics of different sewer systems, such as the degree of dilution and the amount of time the waste spends in transit before taking samples?
Still, Matt Meyer, county executive for New Castle County in Delaware, said his community is working on the Biobot reports.
In addition to county data from a central treatment plant, the county uses readings from its 11 sewage pumping stations that serve more localized areas. “That gives us an insight into where the hot spots are and … where the hot spots develop if the numbers increase,” he said. That helps officials decide where to place mobile stations to screen people.
Wastewater data can also help measure the effect of changes in measures to combat the spread of the virus, Meyer added.
Although he has no idea when a so-called “second wave” may appear with increasing infections across the country, Meyer said, “We are working as if it is going to happen at any time.”
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Kathy Young in New York and Aleksandar Furtula in Nieuwegein, The Netherlands contributed to this report.
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Follow Malcolm Ritter on Twitter: @MalcolmRitter
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The Associated Press Department of Health and Science receives support from the Department of Scientific Education at the Howard Hughes Medical Institute. The AP is solely responsible for all content.
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