Information on wastewater surveillance H5 levels in Oregon was reported in the CDC Morbidity and Mortality Weekly Report (MMWR) yesterday entitled Avian Influenza A (H5) Subtype in Wastewater — Oregon, September 15, 2021–July 11, 2024 . In this study, Oregon’s wastewater surveillance program tested 551 influenza A-positive wastewater samples from 20 communities, taken between September 15,2021 and July 11, 2024, for the H5 subtype. We found that the H5 subtype has been present in Oregon wastewater since bird flu entered the U.S. wild bird population in early 2022. All supporting data is planned for release to the CDC public dashboard Friday, March 7, 2025.
 
Thank you for your continued support and participation in this program.  Your involvement makes this data possible. Further Avian Influenza H5 information is available below.
 
Oregon is starting surveillance for Avian Influenza A (H5N1) Viruses using the H5 subtype.
  • Avian Influenza A, also known as ‘bird flu’, is widespread in wild birds worldwide and is currently causing outbreaks in poultry and U.S. dairy cows (https://www.cdc.gov/bird-flu/situation-summary/).  As part of ongoing surveillance efforts, CDC is collaborating with state and local health departments to use wastewater surveillance to monitor bird flu.
  • In Oregon we measure influenza A and influenza B viral RNA concentrations in wastewater samples. By additionally testing samples for H5 (found primarily in wild bird populations), we will be able to identify the samples where H5N1, a type of influenza A, is likely present. *These results will be made publicly available starting in March 2025. 
 
We expect to see low levels of H5 in Oregon wastewater
  • Wastewater surveillance does not distinguish between human and animal input. Potential animal contributors to wastewater include wild animals, farms using sewer systems (rather than septic systems), and dairy processing facilities.
  • By testing stored wastewater samples from as early as September 2021, we know that the H5 subtype (presumably H5N1) has been present in Oregon wastewater since early 2022, the same time that bird flu entered the U.S. wild bird population.
  • We anticipate that we will continue to see low levels of the H5 subtype in wastewater even in the absence of outbreaks in dairy cattle or human cases and may see higher levels during peak bird migration. We will be monitoring H5 in wastewater for higher levels of H5, especially outside peak bird migration, in conjunction with other surveillance efforts.
 
Additional Resources
 
*Note, while there are other types of bird flu that contain the H5 subtype (collectively called H5Nx viruses), we know from testing wild birds in Oregon that H5N1 is by far the most common.