Morbidity and Mortality Weekly Report (MMWR) yesterday published a study suggesting that wastewater surveillance for detecting influenza viruses such as H5N1 avian flu can support public health preparedness and the results of a survey finding that 95% of US adults say they would take action to protect themselves if wastewater data flagged disease transmission in their community.
Animal sources identified at 15 sites
For the study, researchers from the Centers for Disease Control and Prevention (CDC) and other public health agencies reported on levels of influenza A virus and the H5 subtype in wastewater from January to August 2024. The study period spans the first 9 weeks of the ongoing H5N1 outbreak in US cattle and poultry, as well as 13 related human infections.
"As part of the response to this outbreak, CDC and state and local health departments are using wastewater surveillance to monitor influenza A virus and the H5 subtype; however, current testing techniques cannot distinguish between human and animal sources," the study authors wrote.
Public health agencies that conduct wastewater monitoring to complement influenza surveillance systems should be prepared to add influenza A virus subtype testing when needed.
Among 309 sites in 38 states that generated sufficient data from monitoring wastewater for influenza A from May 12 to July 13, 2024, 11 sites in four states (California, Illinois, Kansas, and Oregon) detected high concentrations of the virus. Three of the four states also had evidence of human flu activity from other surveillance systems. H5 subtype testing performed at 203 sites in 41 states revealed H5 in wastewater at 24 sites in nine states.
Seven of the nine states with H5 in wastewater reported an H5N1-infected herd, and another state reported an infected herd before the study period. Two states, Colorado and Michigan, documented human H5N1 infections.
Each detection or high concentration triggered the CDC to work with state and local health departments to analyze data from other flu surveillance systems. The agencies also worked with wastewater utilities and agriculture departments to identify potential sources of the virus.
Of the 24 sites with H5 detections, 15 pinpointed animal sources in the sewershed or neighboring county, including eight milk-processing sources. Other sources were meat-processing and dairy facilities, wild birds, domestic poultry farms, and livestock waste from, for example, a truck wash.
"The current zoonotic outbreak of HPAI A(H5N1) virus highlights the importance of coordination across health, agriculture, wildlife, food safety, and other partners," the study authors wrote. "Investigations into wastewater signals also require coordination among public health, academic, municipal water treatment, and community partners."
"Public health agencies that conduct wastewater monitoring to complement influenza surveillance systems should be prepared to add influenza A virus subtype testing when needed to improve understanding of influenza A virus detections in the context of the current HPAI A(H5N1) outbreak," they added. "CDC-funded National Wastewater Surveillance System’s Centers of Excellence are expanding influenza A virus testing and subtyping, which can contribute to source investigations and be deployed at strategic times and places."
75% support public health wastewater monitoring
From July 24 to 26, 2024, Porter Novelli Public Services fielded a nine-question online survey developed with the CDC to 1,016 US adults to gauge their support for wastewater infectious-disease monitoring and protective health behaviors to help shape messaging about wastewater surveillance.
These findings indicate strong support for wastewater monitoring for infectious diseases among U.S. adults across various sociodemographic groups and intention to use reported wastewater data to guide certain health-related behaviors.
In total, 74.6% of respondents strongly or somewhat supported public health wastewater monitoring for infectious diseases. The results were similar across races but varied significantly by age, education, and marital status.
Participants strongly or somewhat agreed (57.8%) that they wanted access to rapid wastewater data, even if it contained insufficient information to determine public health risk or inform specific protective actions.
Black respondents (67.5%) were most likely to say they wanted rapid wastewater data, followed by Hispanic (64.2%) and non-Hispanic people of other races (65.5%), and White people (52.9%). Respondents most supportive of rapid access to wastewater data were men, employed people, and those living in urban or suburban communities.
Nearly all participants (95.3%) said they would consider taking at least one action to protect their health if wastewater data showed a virus such as flu in their area. The most-cited actions were more frequent handwashing (76.1%), avoidance of large gatherings (61.1%), and avoidance of visiting people at high risk for flu-related complications (59.1%).
"These findings indicate strong support for wastewater monitoring for infectious diseases among U.S. adults across various sociodemographic groups and intention to use reported wastewater data to guide certain health-related behaviors," the researchers wrote.
"In addition, most respondents indicated that they wanted access to rapid wastewater data even if information available to determine public health risk or which actions should be taken is insufficient," they added. "Wastewater data can help keep the public informed and should be accompanied by clear public health interpretations."
