New Study Suggests Wastewater Testing Could Track Spread of H5N1 Avian Influenza
Key Insights
A recent study conducted by scientists from Emory, Stanford, and Verily Life Sciences has found potential evidence of H5N1 avian influenza virus spread through wastewater samples. The study, conducted on 59 sewer systems from various states, reveals spikes of influenza A virus that may be connected to the ongoing infection of H5N1 in dairy cattle. This passive approach to tracking infections could offer valuable insights into the outbreak’s scope and spread.
Challenges in Tracking the H5N1 Outbreak
The US Department of Agriculture has reported numerous dairy cow herds infected with H5N1 influenza across multiple states. However, accurately assessing the outbreak’s extent and implementing effective tracking mechanisms pose immense challenges. USDA officials admitted difficulties in obtaining milk producers’ consent for infection tests. Notably, recent tests on milk samples purchased from grocery stores revealed genetic material from the H5N1 virus in 1 out of 5 samples, though the virus was not found to be infectious.
Can Wastewater Testing Help Identify Spread Areas?
The US Centers for Disease Control and Prevention is exploring the feasibility of using wastewater to pinpoint areas of H5N1 virus spread. Scientists need to create a test capable of distinguishing H5 influenza from the broader range of circulating A-strain flu viruses. The collaboration between researchers from Emory, Stanford, and Verily Life Sciences has successfully developed such a test, potentially revolutionizing disease surveillance efforts.
WastewaterSCAN Highights Potential Outbreaks
Researchers involved in the WastewaterSCAN network, an organization monitoring a vast network of wastewater treatment plants across the US, have detected the H5 gene in wastewater samples from sewers near areas where dairy cattle were infected. As levels of the H5 virus gene corresponded with rises in the influenza A virus marker, the researchers suggest a significant proportion of the detected viruses are H5N1. Wastewater samples from the Amarillo, Texas area showed the highest concentrations of influenza A viruses observed in such samples.
Remarkable Early Warning Mechanism
Wastewater testing has proven to be an invaluable early warning system for rising Covid-19 infections. This recent study suggests that it could play a similar role in predicting bird flu outbreaks in farm animals, serving as an early indicator of circulating viruses before public information becomes available. The researchers noted the detection of the H5 marker just before confirmed highly pathogenic avian influenza cases were reported in specific counties, emphasizing the information wastewater analysis can provide.
Implications and Potential Sources
The study authors caution that, despite the observed increases in influenza A viruses across multiple states, the precise sources of the outbreaks are yet to be identified. While permitted milk disposal specifically from dairies contributes to the significant H5 virus spikes registered in early March, the researchers do not entirely discount the possibility of bird or human involvement in the wastewater samples. The researchers urge further investigation to decipher the sources and nature of the circulating viruses.
Study Limitations and Future Research
It should be noted that this study’s results are not conclusive, and further exploration of the sewersheds being monitored is necessary to definitively establish the source of the virus. The testing method employed offers high sensitivity, making the detection of H5 viruses possible, but the actual infectivity of the viruses and their potential to make humans sick remains unknown. The research team sealed their findings through a preprint but seek comprehensive review and publication in a scientific journal for wider assessment.
Continued Diligence Urged
The US Food and Drug Administration has been examining pasteurized milk samples with detected traces of the H5N1 virus. The results thus far have confirmed the milk to be noninfectious and incapable of making people sick. While the wastewater researchers acknowledge that other types of H5 viruses, including low-pathogenic H5 influenza viruses, may be detected, these are not expected to be circulating in the monitored areas presently. The study’s promoters emphasize the importance of this discussion and the imperative need to address prevailing unanswered questions.
