The same sewage surveillance techniques that have become an important tool in the early detection of COVID-19 outbreaks are being adapted to monitor the alarming spread of monkeypox in other communities in the San Francisco Bay Area and beyond.
Before the Covid pandemic, sewage sludge was thought to hold promise as an early indicator of health threats, as people could excrete genetic evidence of infectious diseases in their feces, often before they showed symptoms of illness.
Israel has monitored sewage for polio for decades. But before Covid, risk management in the US was almost exclusively limited to academic activities.
Since Covid, a research alliance with scientists at Stanford University, Michigan and Emory has pioneered efforts to reengineer surveillance techniques to detect the Covid-19 virus – the first time sewage has been used to track respiratory disease.
That same group, the Sewage Coronavirus Alert Network, or SCAN, is now leading the expansion of sewage monitoring for monkeypox, a virus endemic to remote parts of Africa that has infected more than 26,000 people worldwide and more than 7,000 countries within months.
A few days ago, the Biden administration declared the monkeypox outbreak a public health emergency, after declarations in California, Illinois and New York.
And SCAN scientists envision a future in which sewage sludge is used as a threat to public health. “We’re looking at different kinds of things we can test,” said Marlene Wolff, an assistant professor of environmental health at Emory.
Since increasing surveillance in mid-June, the SCAN team has detected monkeypox in several of the 11 Northern California drainage basins it monitors, including two sites in Palo Alto, San Jose, Gilroy, Sacramento and San Francisco.
Funded by grants from the National Science Foundation and the CDC Foundation, SCAN is conducting similar monitoring in Colorado, Georgia, Michigan and four other states and is looking to expand to 300 sites.
It’s one of a growing number of wastewater monitoring projects run jointly by universities, public health agencies and utility departments that are reporting Covid results to state and federal agencies.
Scan sites in California, Georgia, Michigan and Texas and a research team in Nevada are among the few samples that have reported testing positive for the monkeypox virus.
As with Covid, Monkeypox data can be used to compare trends across regions, but there are limitations to what can be achieved. Wastewater monitoring does not identify who is infected; It only reveals the presence of a virus in a specific area. And an expert is needed to analyze the sample. Researchers view wastewater surveillance as a complement to, not a replacement for, other public health tools.
“We’re still in the early stages of uncovering the potential,” said Heather Bischel, assistant professor of civil and environmental engineering at the University of California-Davis. “But what we’ve already seen shows that this kind of monitoring can be adapted to other public health threats.”
Some communities already took wastewater samples before the epidemic to find out what kinds of opioids residents were using. More recently, the technology has also shown promise for monitoring influenza and respiratory syncytial virus (RSV). The Centers for Disease Control and Prevention (CDC) is planning pilot studies to see if wastewater can reveal trends in antibiotic-resistant infections, foodborne infections, and Candida aureus, a fungal infection.
Much of the wastewater testing relies on funding provided through the federal Covid Relief Act. At the Bischel campus, those funds were combined with money from university donors to put together a comprehensive test and treatment program for the school and the city of Davis that included sewage monitoring. Effluent testing is underway under a separate grant.
Currently, the CDC only reports Covid results in its national sewage surveillance system, reflecting the limited number of sewer basins tested for monkeypox to date.
The global spread of monkeypox was first detected in the UK in May and it is thought that the virus can also be passed down through sewage, either through faeces or when an infected person has an open sore.
Sewers in areas of infected people may “light up” with evidence of the disease, if sewage tests can detect it.
“And it’s been enlightening,” says Brad Pollock, chair of public health sciences at UC Davis Health. “It acts as a warning system and you don’t have to persuade people to take individual tests to use the information; It’s passively collected, so you get to see that community more broadly.”
The virus is believed to spread primarily through close skin-to-skin contact and exposure to symptomatic lesions, although researchers are exploring other routes of transmission. For now, the outbreak here is mostly concentrated among men who have sex with men.
The discovery of monkeypox in San Francisco’s sewage system in June, the first of its kind in the country, has raised alarm in a city with a growing LGBTQ+ population. On July 28, San Francisco declared monkeypox a public health emergency and called on the federal government to increase vaccine distribution.
For surveillance in Northern California, SCAN partners with local health officials and universities to collect samples, which it sends to Verily Life Sciences, a health technology company owned by Google parent company Alphabet, for testing. In the Atlanta area, Scan is working with health officials in Emory and Fulton counties.
But not all public health agencies are moving so quickly. A sewage monitoring plan for the virus is now being developed in Los Angeles County alone, which confirmed more than 300 cases of monkeypox by the end of July.
“With each new thing added to the testing platform, we’re learning things,” says SCAN’s Wolfe. “The pandemic really opened our imagination to a tool that already existed but hadn’t been developed to its full potential. That is changing now.”
This story was produced by KHN, which publishes California Healthline, the editorially independent service of the California Health Care Foundation.
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