Spikes of flu virus in wastewater raise questions about spread of bird flu

"Spring Wastewater Samples Show Increased Influenza A Virus Levels Across 18 States, Raising Concerns About Potential Spread of H5N1 Avian Influenza

A recent study reveals spikes of influenza A virus in wastewater samples collected from 59 sewer systems across 18 states this spring, potentially indicating the spread of the H5N1 avian influenza virus. The virus, currently affecting dairy cattle, has led to infections in more than 30 herds across nine states, as reported by the US Department of Agriculture. However, uncertainties persist regarding the scale of the outbreak and the nation's ability to effectively monitor and control it."

"USDA Struggles with Milk Producers' Cooperation in H5N1 Testing, Despite Findings in Grocery Store Samples During a recent news conference, USDA officials acknowledged the challenges in obtaining cooperation from milk producers for infection testing. Despite this, tests conducted on milk bought from grocery stores revealed genetic material from the H5N1 virus in 1 out of 5 samples. Subsequent testing, however, clarified that the virus fragments identified in milk were not infectious."

"Government Mulls Wastewater Surveillance for Tracking Virus Spread, Says CDC Deputy Director

During a recent interagency press briefing addressing the virus spread response, Dr. Nirav Shah, principal deputy director of the US Centers for Disease Control and Prevention, discussed the potential use of wastewater for pinpointing virus-spread areas. He highlighted the necessity of developing a test capable of differentiating H5 influenza from other circulating A-strain flu viruses. Notably, scientists from Emory, Stanford, and Verily Life Sciences, associated with the WastewaterSCAN network, claim to have achieved this milestone."

"Amidst Stable Human Flu Cases, Wastewater Analysis Reveals Surge in A-Strain Viruses Across 59 Treatment Plants In a notable finding, out of 190 wastewater treatment plants currently monitoring sludge samples for influenza A, 59 observed increases in A-strain viruses this spring, coinciding with stagnant or decreasing human flu cases. Speculations arose among wastewater experts regarding the potential sources, including H5N1 avian influenza infections in dairy cattle and other animals. To investigate further, the WastewaterSCAN team devised a test targeting the H5 gene of the flu virus. They applied this test to stored samples from sewer systems near areas in Texas with reported cases of H5-positive dairy cattle, albeit excluding wastewater directly from the farms. The team evaluated both a genetic marker for influenza A viruses and specific genetic markers indicative of H5 viruses."

"In Early March, Rise in Influenza A Markers Coincides with Increase in H5 Virus Markers

A notable correlation emerged as levels of the influenza A virus marker surged, closely followed by a rise in H5 virus markers. Remarkably, the concentration of the H5 gene in the samples nearly matched that of the overall influenza A viruses, indicating a substantial presence of H5N1.

Furthermore, the study highlighted that the concentrations of influenza A viruses detected in wastewater sludge samples from the Amarillo, Texas, region were "among the highest ever measured," underscoring the severity of the situation."

"Wastewater Study Indicates Potential Early Warning for Bird Flu Outbreaks in Farm Animals

Examining stored sludge samples collected between February 4 and April 16 from two treatment plant sites within the City of Amarillo watershed and a third plant in Dallas County, researchers identified noteworthy patterns. Notably, wastewater processing plants in the Amarillo area were found to permit disposal of animal byproducts, including discarded dairy milk, potentially explaining the elevated levels of influenza A and H5 viruses detected in the samples.

Drawing parallels with wastewater's role in predicting Covid-19 outbreaks, researchers suggest its potential as an early indicator for bird flu outbreaks in farm animals. Dr. Alexandria Boehm, a professor of civil and environmental engineering at Stanford University, highlighted the significance of detecting the H5 marker just before confirmed highly pathogenic avian influenza cases emerged in the counties.

The study, available as a preprint on the BioRxiv server pending rigorous peer review, emphasizes that no H5N1 outbreaks in cows were reported in the tested sewersheds. Instead, the researchers attribute the observed spikes in H5 virus levels in early March to permitted milk dumping.

Despite these findings, researchers caution that the H5 genetic material detected in wastewater might not solely originate from dairy cattle; it could also derive from birds or even humans."

Researchers Lack Clear Insight on Source of Influenza A Virus Surge Across States Addressing the surge in influenza A virus levels across multiple states, researchers express uncertainty about its origin. Dr. Boehm emphasized the need for further investigation, stating, "We don't know the answer to that question. It is something that I think needs to be followed up on." Considering the possibility that the virus spike could be linked to dumped milk or other animal waste in the monitored sewersheds, researchers caution that this assumption requires further validation. However, if confirmed, it suggests a significantly broader outbreak than presently acknowledged."

"Dairy Industry Activities Could Potentially Contribute to H5 in Wastewater, Study Suggests

The study authors speculate that dairy industry operations within monitored sewersheds might serve as a primary source of H5 in wastewater. They highlight the likelihood of additional, yet unidentified outbreaks among cattle whose milk is directed to these facilities, as infected animal milk is typically diverted from the food supply.

However, the researchers caution against drawing definitive conclusions from their findings. Without pinpointing specific sources within the monitored sewersheds, the virus's origin cannot be conclusively established.

"While multiple indicators point towards animal sources," the paper states, emphasizing the need for cautious interpretation.

The researchers underscore the sensitivity of their testing method, capable of detecting minute genetic material from H5 viruses. Yet, they clarify that their approach doesn't determine the virus's potential to infect humans or cause illness. Dr. Boehm explains that they didn't attempt to culture the virus to assess its infectivity."

FDA Finds H5N1 Traces in Pasteurized Milk, But Assures Non-Infectiousness

Last week, the US Food and Drug Administration (FDA) reported detecting traces of the H5N1 virus in pasteurized milk samples. However, they confirmed that the virus was non-infectious and posed no threat to human health.

While analyzing wastewater, researchers also acknowledge the possibility of detecting other H5 virus strains, including low-pathogenic H5 influenza viruses. However, they assert that such strains are not anticipated to be circulating in the monitored areas currently.

Dr. Boehm stressed the ethical obligation to disseminate their findings through a preprint publication, initiating vital discussions within the scientific community. She emphasized the urgency of addressing unanswered questions surrounding the detected phenomena."