CDC unveils wastewater dashboard to track the spread of H5N1 bird flu

In the face of reluctance among dairy farmers to report H5N1 bird flu outbreaks and test workers, the Centers for Disease Control and Prevention (CDC) is pioneering an approach to track the virus's spread: monitoring wastewater. This innovative strategy aims to fill crucial gaps in understanding the rapid dissemination of the virus, particularly in regions where reporting from traditional channels remains limited.

The CDC's public dashboard, expected to be revealed today, will track influenza A viruses detected in sewage collected from 600 wastewater treatment sites across the United States since last fall. While the testing is not H5N1-specific, it encompasses influenza A strains, providing insights into unusual viral activity.

"The presence of high levels of influenza A in wastewater could be a reliable indicator of unusual viral circulation in a particular area," Amy Kirby, the lead of the CDC wastewater team, told STAT News.

Kirby noted that certain wastewater collection sites have observed significant increases in influenza A virus levels since late March or early April despite indications suggesting the end of the 2023–2024 flu season.

 "It's a very limited phenomenon — the vast majority of our sites are not seeing this," she added, underscoring the localized nature of the observed spikes.

While concerns have been raised about implicating nearby dairy farms based solely on wastewater data, Kirby stressed the mobility of animal operations, emphasizing the need for comprehensive surveillance.

It has been learned that animal operations, particularly within the dairy sector, exhibit more mobility than anticipated, she added. Cows and milk traverse between farms. Consequently, the presence of a dairy processing facility within a community does not guarantee local milk sourcing.

A call for collaboration and data sharing accompanies the unveiling of the dashboard.

“We are working to understand that signal better, but in the meantime, we want to make sure all of that data is available for any groups that are working on this to have access to it,” Kirby explained. “There are so many players here who have valuable input and information. They may see things in this data that we don’t see — patterns that we’re not aware of — and we hope that they will reach out and help us."

Despite the promising outlook, the CDC remains cautious about the nationwide deployment of H5N1-specific tests, prioritizing resources based on influenza A activity. Additionally, the CDC monitors sewage for other pathogens, including SARS-CoV-2 and respiratory syncytial virus (RSV), highlighting the multifaceted nature of wastewater surveillance in public health.

As the CDC continues to refine its wastewater monitoring approach, Kirby emphasized the importance of adaptation to evolving circumstances.

This presentation of high virus concentrations in milk from dairy cattle was unexpected. Current efforts focus on swiftly understanding the various pathways through which milk and its byproducts enter wastewater systems, she clarified.

The CDC's wastewater dashboard represents a pioneering effort to leverage unconventional data sources for disease surveillance, offering a promising tool in combating the spread of H5N1 bird flu and other infectious threats.

"We are very much focused on this as an immediate response to the current situation," reassured Kirby. "And we’ll be continuing to work through this as the situation evolves — hopefully resolves. But if we start getting into the seasonal flu season, we’ll have to think about some additional testing to tell those things apart."