Sewage surveillance has proved to be a valuable tool in monitoring the spread of monkeypox as public health officials keep a wary eye on the potential spread of another pandemic.
Environmental health experts have begun testing water sewage before it’s treated for genetic material — DNA and RNA — of the monkeypox virus, which indicates that the virus is present in the community.
“With wastewater monitoring, you have one sample that represents an entire community on a given day,” said Heather Bischel, an assistant professor in civil and environmental engineering at the University of California, Davis. “It’s kind of a snapshot, and you can redesign the analysis of that sample relatively easily to pivot from one pathogen target to another, which is one of the reasons that makes this method so useful.”
The presence of monkeypox RNA in wastewater could be an indication that cases in that area are increasing. It also gives public health departments a warning if it appears that a surge is brewing. Wastewater surveillance is a public health tool that gained prominence during the COVID-19 pandemic for its usefulness in alerting researchers to potential outbreaks, often detecting cases before symptoms arise.
“For every new thing that we monitor, we’ve gone through a process of not only making sure that from a technical perspective, the tests that we’re doing are very sensitive and very specific to the targets that we’re looking for,” said Dr. Marlene Wolfe, an environmental health engineer at Emory University’s Rollins School of Public Health. “We also go through a process of looking at what is the relationship between that measurement from wastewater and disease in the community.”
Wolfe has helped lead the initiative to trace pathogens in wastewater in several Northern California sewersheds, starting with COVID-19 in 2020 with a project called the Sewer Coronavirus Alert Network. A new national effort called WastewaterSCAN uses the same methods to test for COVID-19 and its variants, monkeypox, influenza, and respiratory syncytial virus. The goal is to sign up 300 sewersheds across the country. So far, the research team has 41 sign-ups across 10 states.
The surveillance method could be scaled up to more sewersheds with relative ease. The infrastructure for testing solid sewer material exists for other pathogens including COVID-19. The process for determining the presence of monkeypox, including the ways the sample is collected, handled, and prepared, is the same as what is used to detect COVID-19.
“All of that is the same, and then we just add on that test at the end to be able to add in monkeypox, for example,” Wolfe said. “We do a lot of quality testing to make sure it’s going to work, but everything can be used through the same system.”
The turnaround time for getting results is short, between 24 and 48 hours, Wolfe said. An early goal for the research team behind SCAN was to prioritize speed in order to make their results as helpful to public health authorities as possible.
Health departments first began reporting cases in mid-May, and the tally has steadily increased since. To date, the Centers for Disease Control and Prevention has confirmed about 9,500 infections in all but one state.
The outbreak had its genesis in Europe and was first identified in men who have sex with men. The once-obscure virus normally endemic to West and Central Africa spreads primarily through close contact with lesions and bodily fluids from an infected person or materials used by an infected person. The infection typically causes flulike symptoms, swollen lymph nodes, and pustules and lesions on the skin of the arms, hands, feet, face, and inside the mouth.
While not a sexually transmitted disease in the traditional sense, the virus’s course of transmission has resembled that of an STD. In many cases, the rash has appeared in the genital region, causing doctors to diagnose the infection inaccurately.
The Biden administration has ramped up efforts to address the outbreak, including by giving healthcare providers better guidance for accurately diagnosing monkeypox cases. The Department of Health and Human Services declared monkeypox a public health emergency in early August. Soon after, HHS gave approval for healthcare providers to use an alternative method for administering the scarce doses of vaccine intradermally, a way that resembles how the vaccine is administered to prevent smallpox.
