When the Biden Administration announced its plan of action to respond to the threat of avian H5N1 flu, most of the steps being taken were similar to previous threats – targeted patient and animal screenings, bolstered laboratory capacity, and regular communications with and updates for the public and policymakers. But one item on the list may have struck people as newer than the rest – the incorporation of wastewater monitoring into an emergency response. The federal government allocated $3 million for a wastewater pilot study, and an attempt to quantify contributions from animal sources.
Beginning in 2020, wastewater monitoring has been utilized as a component of the enhanced surveillance for COVID-19. Since then, it has been repeatedly tapped. It was employed in monitoring for the presence of Mpox and other diseases—which resulted in the detection of polio viruses in New York City. There has been an effort to determine how to incorporate wastewater screening into disease monitoring in schools in Houston. And, a separate project recently demonstrated its possible usage to detect an elevation in the presence of certain illicit drugs, flagging the need for rapid intervention by public health agencies.
As these examples demonstrate, its employment is expanding rapidly. Over the last few years, CDC has provided funds, analytics, training, and technical assistance for wastewater surveillance across the country. Consequently, local and state public health departments have begun to add this method to bolster other more traditional disease detection and monitoring options. Today, there is some level of wastewater surveillance in all fifty states plus Puerto Rico, USVI, Guam, and six tribal communities using samples from more than 1,500 sites representing about 40% of the American public.
But just how valuable is this method? Does it complement or replace other tools and is it likely to become a routine approach used in disease surveillance?
CDC and other public health officials certainly believe its addition to the public health toolkit is valuable when combined with other surveillance data from multiple sources. In conjunction with these other sources, wastewater monitoring can provide a more complete picture of disease spread within a community and allow public health practitioners to respond quickly.
What is wastewater surveillance?
Wastewater surveillance is an approach to testing sewage for the presence of nucleic material from specific harmful pathogens at the neighborhood or community level. This approach is possible because infected individuals with certain illnesses shed genetic material from pathogens in their feces and bodily fluids. Since the sewage generally comes from many different homes in a community or a portion of a community, wastewater monitoring cannot identify specific people or even specific buildings where there may be people with certain infections.
One of the reasons why wastewater surveillance has developed so successfully is that it can be an early detection or warning system regarding the presence of disease. It can pick up genetic material from potential pathogens even before people start showing symptoms and, importantly, it requires no action on the part of an individual such as seeing a doctor or providing a laboratory sample for testing. With the COVID-19 pandemic, it also proved useful in detecting the presence of different variants of the SARS-CoV-2 virus and, as its recent preliminary usage in the screening of H5N1 spread, it may also prove useful in other ways.
What are its limitations?
Wastewater surveillance lacks specificity about the individuals who are infected, the number of people who are infected, what stage of illness they are experiencing, and whether they are symptomatic. Because it generally tests only municipal sewage systems, it will not capture waste from homes on private sewers or from other decentralized systems.
Consequently, wastewater surveillance may under-represent certain populations. For instance, those in rural communities, where individual sewer disposal systems are more common, may be missed.
In addition, because wastewater surveillance generally is done on a community-wide basis, it can be difficult to distinguish between pathogens coming from hospitals versus community sites or from farms versus residential neighborhoods that are in the same geographic areas.
Finally, there are delays in getting the results from this method (as there are with all surveillance systems). It can take more than five days from the time waste enters the system to the confirmation of results.
Is wastewater surveillance widespread?
In 2020, the CDC created the National Wastewater Surveillance System (NWSS) to build the nation’s capacity to collect and track COVID-19 and to provide a centralized repository for such data. It offers support for local and state systems to become established, funds public and commercial laboratories to provide testing, and it operates a secure online CDC NWSS Data Collation and Integration for Public Health Event Response (DCIPHER) platform that provides data management and analysis. CDC and its partners (like APHL) also provide technical assistance for wastewater treatment plant operators, laboratories and public health departments that are interested in establishing wastewater surveillance and sharing the data with CDC.
CDC has contracted with wastewater testing companies to supplement the operating NWSS sites in municipalities where monitoring might not otherwise occur. Despite this, not all communities receive federal support or report their wastewater data to the CDC.
Thus far, its primary usage in avian flu activities has been via broad monitoring for any type of Influenza A viral material in wastewater. Such monitoring cannot distinguish between the less concerning influenza sub-types that circulated during the last flu season as well as the novel H5N1 virus. However, since we are past the height of seasonal flu cases, any noteworthy increase in viral material might well be due to the presence of H5N1. Additional laboratory testing is needed to confirm that.
What remains to be done?
What are the barriers to wastewater surveillance being widely available and realizing its full potential? Wastewater surveillance has been largely reliant on specialized, but short-term COVID-19 funding. Much of that funding will end in another year or so and, without new sources of funding within CDC’s core annual budget, the system will be in jeopardy. The Biden Administration requested $20 million for wastewater surveillance at CDC as part of its core budget in the proposed FY25 budget but there is a good deal of uncertainty regarding Congress’ willingness to add new funding for such work to the agency’s core budget. Even if the $20 million was approved, this level is insufficient to support an entire national wastewater surveillance program. The ultimate outcome of that request is yet to be determined.
Furthermore, while local- and state-level data is produced and collected by the national program, the utilization of wastewater data is lagging and public health departments in many jurisdictions struggle with ways to incorporate it into more traditional surveillance approaches. While many public health laboratories have developed and implemented wastewater testing methods, if funding is not available for supplementary contracts with commercial labs, they would be expected to accommodate additional samples while keeping up with increased expectations for new testing targets.
How do we keep wastewater monitoring sustained?
The evidence appears solid that wastewater surveillance for avian flu and other pathogens is a useful complement to the already existing disease surveillance efforts at CDC and state, tribal, local, and territorial health departments. To ensure it remains sustained where it already exists and expanded to other areas of the nation, more resources and personnel are needed. Most infectious disease experts agree that the spread of potentially harmful new viruses will continue to be a threat and it only makes good sense to utilize this method to protect the public.
John Auerbach, SVP, Federal Health, ICF
John is ICF’s primary federal health expert and thought leader within the company’s public sector business. Amid tremendous global health and social challenges, ICF’s capabilities and solutions for federal health agencies have never been more relevant. John’s thought leadership advances ICF’s combination of proven domain and scientific expertise with leading-edge analytics and technology solutions to drive improved health outcomes for clients.
John came to ICF from the Centers for Disease Control and Prevention (CDC), where he most recently served as the director of intergovernmental and strategic affairs. In this role, he was the lead strategic advisor on CDC engagement with government agencies at the federal, state, local, tribal, and territorial levels, as well as public health and other external partners. He also had oversight of CDC’s health equity workgroup and served as the chief equity officer for CDC’s COVID-19 response.
Dr. Ewa King, Chief Program Officer, Association of Public Health Laboratories, Maryland
Ewa King, Ph.D. is Chief Program Officer at the Association of Public Health Laboratories (APHL), overseeing the association’s public health programs including infectious disease, environmental health, food safety, emergency preparedness and response, newborn screening and genetics, and informatics. Previously, Dr. King served as director of the State Health Laboratories, a division of the Rhode Island Department of Health (RIDOH) in Providence, RI. In this role, Dr. King directed laboratory scientists and support personnel in laboratories that provide testing services for state and national regulatory, law enforcement, environmental monitoring, and disease surveillance purposes. During the COVID-19 pandemic response, Dr. King served as a subject matter expert on laboratory and testing topics.
