Evidence is growing that monkeypox, like Covid, can be reliably detected in wastewater. Yet the US has moved far too slowly to include the virus in its regular scans of sewage for coronavirus. By the time the Centers for Disease Control and Prevention launches a program in the next month or two to look for monkeypox, the worst of the outbreak is likely to have passed.
When someone is infected with a virus, they “shed” it in various ways — feces, urine, saliva, semen, or, if there is a rash involved as with monkeypox, through skin that is sloughed off in the shower. All of it goes down the drain, and with it, evidence of the level of infections in a community.
Since 2020, researchers have looked for bits of SARS-CoV-2, the virus that causes Covid, in sewage. The idea is that infected people are flushing a lot of viral genetic material down the toilet before they show symptoms or the virus can be detected by a PCR or at-home test.
That makes sewage a good sentinel for a rise in cases, allowing public health authorities to control the outbreak by adjusting their recommendations on things like wearing masks or social distancing.
With Covid, it has also become the most reliable indicator. The advent of easy-to-use at-home tests has meant far fewer cases are being formally reported to public health authorities. Only wastewater testing reflected the true spread of the virus in the delta and omicron waves.
Scientists still have a limited understanding of how people shed monkeypox. Still, any signal in the sewage in recent months could have helped direct scarce resources — testing, vaccines and treatments — and increase education in places where cases might be bubbling up.
So why not make every effort to immediately expand the existing infrastructure to look for monkeypox? What is learned could help rein in the current outbreak of a sometimes-painful disease that as of Aug. 29 totaled more than 18,100 cases. And even as cases decline in New York City, giving health officials there hope that the virus is receding, a better surveillance effort would help the country respond to future outbreaks, whether of monkeypox or some other pathogen.
The problem in the US is the piecemeal system for wastewater detection. The Covid-19 pandemic prompted the CDC to set up the National Wastewater Surveillance System, which acts as a kind of clearing house for data from individual health departments. The agency provides funding for wastewater testing, which is performed by a wide range of groups from universities to hospital systems to city public health systems. And the CDC makes recommendations about methods to collect and analyze samples for Covid, though not yet for monkeypox.
But they are just that — recommendations. When it comes to determining which pathogens to test for, the decision remains in the hands of local authorities, not the CDC. That’s partly a reflection of a CDC culture better geared to operating as a data and research hub than as the frontline public-health agency that quickly responds to an emerging threat.
That has meant few places have bothered to test wastewater for monkeypox. Those that have added the virus to their analyses have been frustrated by the lack of a system at the CDC for formally collecting and publicly sharing the data.
The beauty of wastewater is that it is an unbiased reading. A single sample can reflect thousands of people in a given community, whether or not they have symptoms.
Monkeypox virus was first detected in wastewater in the San Francisco Bay Area in late June by a group of researchers from Stanford University and Emory University, who since late 2020 have run the Sewer Coronavirus Alert Network, or SCAN. That result came barely a month after the first case of the virus was identified in the US, and at a time when clinical testing was frustratingly limited.
By mid-July, the team had discovered the virus in seven of the 11 sites it monitors in the Bay Area. A few weeks later, after expanding monitoring to sites in seven other states, the group had detected monkeypox in wastewater in Georgia, Idaho, Michigan and Texas.
That’s proof that wastewater can be quickly deployed for emerging infections. Scientists are becoming adept at understanding how to determine the best way to collect samples (stomach-turning as it may be, there is debate over testing liquids versus solids) and quickly designing ways to accurately analyze them.
Better, the group’s work suggests wastewater testing for monkeypox can be quite sensitive. At the time the first sewage samples from Idaho came back positive for monkeypox, the state had reported only seven cases of the virus.
CDC’s wastewater team is slowly starting to adapt. The agency said it would temporarily expand its data collection to include monkeypox in the next four to six weeks and by early 2023 would ask its partners to look for influenza, norovirus, a fungus called Candida aurus and certain kinds of antibiotic-resistant bacteria.
That progress is welcome, but belated. The US might only be a few months into the monkeypox outbreak, but imagine if a concerted effort to detect it in sewage had materialized sooner. Public health authorities would have had a better handle on the scope of the spread and could have ensured vulnerable communities were informed about the virus.
Covid, polio, monkeypox — these won’t be the last pathogenic threats. The US should be prioritizing a robust and well-coordinated wastewater detection system that can quickly pivot to and guide our response to whatever health emergency comes next.
Bloomberg
