Wastewater surveillance may complement other existing human surveillance systems to monitor influenza. Wastewater data cannot determine the source of influenza A viruses. Detections could come from a human or from an animal (like a bird) or an animal product (like milk from an infected cow).

About CDC’s Wastewater Program (NWSS)

How Wastewater Monitoring Works

Wastewater Data for Avian Influenza A(H5)

H5 detection in wastewater in the past week

This interactive map shows current site-level data for avian influenza A(H5) viral RNA detections in wastewater. Each dot on the map represents a wastewater sampling site. For each site, results are reported as “H5 Detection” when any of the samples were positive during the week reported. When avian influenza A(H5) virus is not detected in any of the samples, then the site is classified as “No Detection.” All data are preliminary and may change as more reports are received. Data will be updated on this site every Friday, based on data submitted to CDC by the end of the day on the previous Wednesday.

Data Interpretation and Limitations: Laboratory tests used for avian influenza A(H5) virus monitoring in wastewater can tell us if the genetic material from the virus (viral RNA) is present in untreated community wastewater. If avian influenza A(H5) viral RNA is detected, it means that H5 virus was present in the wastewater that flows to the treatment plant.

Wastewater data cannot determine the source of avian influenza A(H5) viruses. They could come from a human or from an animal (like a bird) or an animal product (like milk from an infected cow), and detections of avian influenza A(H5) virus in wastewater do not necessarily indicate human cases. During the spring and summer of 2024, investigations in many states with avian influenza A(H5) virus detections in wastewater revealed likely animal-related inputs including milk-processing inputs. Learn more about the current outbreak of avian influenza at H5 Bird Flu: Current Situation.

CDC, state and local public health departments, and other partners are closely monitoring the data from these wastewater sites to identify potential contributing factors. Wastewater results for avian influenza A(H5) virus provide an additional source of data to complement traditional influenza surveillance systems and inform public health planning and response efforts. Efforts to monitor avian influenza A(H5) virus activity using wastewater data are likely to evolve as the methodologies and interpretation are evaluated and refined.

Click on the legend below to see detections.

H5 detection in wastewater in the past six weeks

This searchable table shows site-level data for avian influenza A(H5) viral RNA detections in wastewater for the past six weeks. The date in the column header is the last day for that week of sample collection. The table shows if:

+ H5 was detected at the site

– H5 was not detected at a site

No Data No samples were taken for that site or no data is available for that site

To filter for sites with a recent H5 detection, type + in the search bar.

Wastewater surveillance may complement other existing human influenza surveillance systems to monitor influenza. Avian influenza A(H5) virus data in wastewater include data collected and reported to CDC’s National Wastewater Surveillance System (NWSS) by:
- A CDC contract partner (Verily Life Sciences, LLC).
- An academic partner group (WastewaterSCAN): These data were collected as part of a partnership between Stanford University, Emory University, and Verily funded philanthropically through a gift to Stanford University. Find more about these and use at: wastewaterscan.org/about/#15.
- State and local public health departments: Data from state and local health departments were reported through the NWSS program and funded through the Epidemiology and Laboratory Capacity for the Prevention and Control of Emerging Infectious Diseases (ELC) Cooperative Agreement.
Each wastewater sampling site can represent all or part of a sewershed, which is the geographic area contributing wastewater to a sampling location. Sewersheds can encompass populations of varying sizes and may cross county or state boundaries.
In each wastewater sampling site, wastewater sampling and testing occurs one or more times during the week.
See Data Methods to learn more about how data is calculated and methodology.