Bird flu must be controlled in wastewater, pandemic experts say

PEpidemics start slowly (a few cases here, a few there) until suddenly people get sick or die everywhere. Early detection through wastewater monitoring can help short-circuit that cycle.

It is difficult to know what is happening right now with highly pathogenic avian influenza A H5N1 (bird flu), which is spreading rapidly among cows and other mammals. The outbreak has raised concerns among virologists and epidemiologists that the current spread among mammals could allow the avian flu virus to adapt to mammalian physiology, preadapting it for sustained spread among humans, which could be catastrophic.

In its current form, H5N1 is already quite dangerous to humans. Since 2003, avian flu outbreaks among poultry have resulted in 880 documented cases of suspected bird-to-human transmission, with around 50% of cases resulting in death. These cases, however, have occurred primarily among people close to birds, such as those who kept small flocks in their backyards and poultry farm workers.

If the H5N1 virus gains the ability to be transmitted sustainably from person to person, we could have another deadly pandemic on our hands.

These advances are of great concern to scientists like us working on pandemic preparedness and response. We believe there is an urgent need to develop the capacity to rapidly detect and monitor possible spread of H5N1 to humans, including sustained human-to-human transmission. This will be challenging, if not impossible, by relying primarily on traditional public health surveillance approaches. A relatively new tool, wastewater surveillance, showed great potential during the Covid-19 pandemic for early detection and monitoring of that threat on a large scale, but remains largely underutilized for H5N1 at this precarious time. .

Our team established New York City community wastewater surveillance for SARS-CoV-2, analyzing the waste of 8.5 million New York City residents, as well as travelers and tourists who use the bathroom while out on the town and, yes, the waste of many New York City residents. dogs, rats, birds and other animals. This approach demonstrated the potential for early detection of SARS-CoV-2 waves and emerging and re-emerging infectious disease outbreaks. For example, our team documented the first evidence of the Omicron variant in the US, which was present in New York City wastewater 10 days before the first clinical case was identified in the US. through traditional surveillance.

When a case of acute flaccid paralysis caused by vaccine-derived poliovirus type 2 was reported in an unvaccinated person in Rockland County, New York, wastewater from there and surrounding counties showed the presence of poliovirus up to 25 days before and 41 days after the onset of the disease. symptoms in that patient, indicating the presence of a much larger outbreak than previously appreciated.

This polio test was performed retrospectively, using stored wastewater samples analyzed after The cases were detected through traditional public health surveillance, when the outbreak was already underway. However, if implemented sooner, wastewater surveillance could have detected this event more quickly than traditional surveillance, giving public health authorities and the public more time to prepare and mobilize.

In many areas of the US, human waste flows from toilets through sewers to central municipal wastewater treatment facilities, where it can be sampled and analyzed for the presence and levels of pathogens. However, pathogens circulating among animals are also present in residential sewers as a result of runoff into sewer sheds and other inflows, the presence of animals such as rats in sewers, or the discarding of large volumes of milk. contaminated from dairy cows with H5N1 infection in the sewage system. .

Wastewater monitoring systems exist throughout the United States; most are part of the National Wastewater Surveillance System, which is supported by the Centers for Disease Control and Prevention. This system is critical to national pandemic preparedness and response. While it has primarily been used to monitor Covid-19, there is a chance it could keep an eye out for a broader range of public health emergencies, including threats from infectious diseases such as H5N1, industrial accidents or bioterrorism. A recent preprint from US researchers shows that community wastewater monitoring can detect animal contributions of H5N1 influenza, validating the use of wastewater surveillance for zoonotic diseases (infections that are transmitted between people and animals).

At this stage of the H5N1 situation, it is essential to quickly detect contagion to the human population. Because community wastewater contains both human and animal waste, the exclusive use of community surveillance makes it impossible to quickly detect and differentiate human outbreaks of H5N1 that occur alongside animal outbreaks. Another limitation is that at the beginning of an outbreak, precisely when it is most important to detect it, relatively few people are infected and the concentration of the pathogen may be too low to detect it.

To address these limitations, we initiated a pilot study of wastewater surveillance within the New York City public health care system, in collaboration with NYC Health and Hospitals. As part of this work, we have been continuously monitoring wastewater at four H+H facilities for influenza and SARS-CoV-2, and have consistently found that we can detect surges in genome copies in hospital wastewater earlier. of sudden increases in clinical cases. reported through traditional surveillance approaches. We have also monitored and detected mpox at different points when there were concerns about surges in cases of that infectious disease. (This pilot is using technology developed by Sentinel Biotech, a company that two of us, JD and MT, co-founded.)

Wastewater from these facilities reflects the activity of thousands of inpatients, outpatients, visitors and employees. Routine testing of hospital wastewater can provide early detection and monitoring of potential infectious disease threats. Emergency rooms and hospitals are where very sick people show up first, and sewage samples come from fewer people. It is also important that no animal waste is present in hospital wastewater, meaning that detection of any H5N1 and other zoonotic pathogens in hospital wastewater represents spillover activity to humans.

To be adequately prepared for the next pandemic, we believe it is critical that wastewater surveillance systems be able to distinguish between human and animal contributions of infectious material to sewer systems. We are now actively developing genetic tests based on the H5N1 sequences that the US Department of Agriculture recently released that can be used to test hospital wastewater in New York City. Data from these efforts, along with traditional surveillance data, will provide vital opportunities to improve early detection of H5N1 activity in humans under this current threat, as well as for future health crises.

We believe that more investment is urgently needed to rapidly expand wastewater surveillance capabilities for early detection and monitoring of a broader range of pathogens with pandemic potential than is currently under scrutiny. Wastewater monitoring is an ideal tool due to its low cost, ability to cover large populations, and early detection capabilities. In the short term, responses by local, state, and national public health agencies should include immediate deployment of wastewater testing for H5N1.

Since the most likely source of future pandemics will be microbes circulating in the animal kingdom, the settings considered for wastewater surveillance for zoonotic pathogens such as H5N1 should be expanded to include waste collected directly from facilities such as hospitals, large-scale emergency and outpatient care centers. healthcare providers, schools and universities, and nursing homes to enable more rapid and definitive detection and differentiation of outbreaks in animals from contagious activity in humans leading to sustained community transmission.

Denis Nash is an infectious disease epidemiologist, professor of epidemiology at the Graduate School of Public Health at the City University of New York (CUNY), and executive director of the CUNY Institute for Implementation Science in Population Health. John Dennehy is a virologist, professor of biology at Queens College of CUNY, and co-founder and president of Sentinel Biotech LLC. Monica Trujillo is a professor of biology at CUNY Queensborough Community College and co-founder and chief technology officer of Sentinel Biotech LLC. Leopolda Silvera is deputy director of global and public health initiatives at NYC Health + Hospitals.