Experts say that detecting pathogens in sewage treatment plants, but needs long-term investment

Monitoring of wastewater systems has proven useful during the COVID-19 pandemic and deserves further investment to respond to future threats, according to a new report from the National Academies of Sciences, Engineering and Medicine (NASEM).

But there is room for improvement. The report highlights five core pillars for developing a stronger National Wastewater Monitoring System (NWSS), calling for one that is “flexible, equitable, integrated, viable and sustainable”.

In 2020, the CDC launched the NWSS in response to the COVID-19 pandemic, as these systems can mark biomarkers of infection in municipal sewer systems — including DNA or RNA — and track trends or emerging variants, according to a NASEM press release.

Given the rise in home testing, where the results are rarely communicated to public health systems, wastewater monitoring has become even more relevant, said Guy Palmer, PhD, of Washington State University in Seattle and chair of the committee that wrote the report, during a webinar on Thursday.

It is also helpful because it is unaffected by test availability, test-seeking behavior and access to health facilities, he added.

As of fall 2022, these systems can now track more than a third of the U.S. population, Palmer said.

“Critically, the data consistently leads to hospitalization data,” he said, noting that it was not unusual for surveillance data to serve as a “warning signal” to hospitals, allowing them to postpone elective surgeries to preserve intensive care unit beds prior to a predicted increase.

However, the current distribution of wastewater monitoring is uneven, not fully representative and not equitable, Palmer said, as these systems were developed on a “will-to-participate” basis.

The future of supervision

A future NWSS should be able to track multiple threats simultaneously and “quickly switch to new threats,” the report said. Such surveillance has already helped detect other diseases besides COVID-19, including polio and monkeypox outbreaks last year, Palmer said, and could also be used to screen for antibiotic resistance.

The report calls for the CDC to establish an “open and transparent process” for determining potential surveillance targets based on three criteria: “(1) significance of the threat to public health, (2) analytical feasibility for wastewater monitoring, and (3 ) usefulness of wastewater surveillance data at Community level to inform public health actions.

Asked if existing surveillance systems can detect new threats, or are “pathogen-agnostic,” committee member John Scott Meschke, PhD, also of the University of Washington, said most systems “target very specific pathogens.”

With regard to equity, the commission stressed that such a future NWSS should cover a mix of demographics, “engage underrepresented communities” and have the capacity to extrapolate these findings to communities that lack sewerage where possible.

Palmer noted that the homes of 16% of the US population are not connected to a wastewater treatment plant, but these individuals can still be tracked through work or school buildings that are connected to treatment plants.

In terms of system usability, wastewater surveillance data has recently been used to help determine where pop-up vaccination and testing clinics were needed, Palmer said.

And of course, such a system must be “operationally and fiscally sustainable,” he said. The main reason municipalities share for not participating in surveillance is the “burden” required in terms of expertise and personnel, he added.

The commission has urged the CDC “to work to reduce the financial and capacity barriers,” Palmer said. “The effectiveness of the national system will depend on predictable and sustainable federal investment,” he added.

In addition, the committee also suggested establishing “seneches”, such as international airports or other gateways, zoos and farms, to detect emerging pathogens more quickly.

Privacy Concerns

While monitoring systems raise privacy concerns, Palmer said the commission felt that because of the aggregated nature of the data, “the benefits of wastewater monitoring outweigh the existing privacy concerns.”

Regardless, the CDC has recommended convening an ethics advisory committee that will “clearly communicate how the data is used and not used,” Palmer said, and provide a “strong firewall” with law enforcement.

However, according to the commission, surveillance data has been used to map substance abuse, which is of interest to law enforcement and public health officials. So that “firewall” is more specific to reusing data to identify specific individuals who may be breaking the law, said committee member Michelle Mello, JD, PhD, of Stanford Law School and Stanford School of Medicine.

Individuals can’t be identified from wastewater samples, but “technology changes,” Palmer said, and so data-sharing policies will need to be reconsidered over time.

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    Shannon Firth has been reporting on health policy since 2014 as a Washington correspondent for MedPage Today. She is also a member of the site’s Enterprise & Investigative Reporting team. Follow

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