The recent discovery of H5N1 avian influenza spreading through dairy herds in the U.S. could potentially indicate a threat to human health. As wastewater monitoring presents a viable method of monitoring certain animal pathogens, virologists and public health officials are pursuing wastewater testing to gain better visibility on where H5N1 might be spreading. In response to these concerns, the U.S. Centers for Disease Control and Prevention (CDC) has established a new influenza A wastewater tracker as part of its surveillance for the H5N1 strain.

The CDC data dashboard categorizes current influenza A levels compared to levels seen at the same time during the 2023-2024 season. When levels are at the 80th percentile or higher, the agency works with state and local partners to better understand factors that could be contributing to these levels.

In the first two weeks of May 2024, 230 sites from 34 states met the data reporting criteria, and three sites in three states were at the high level: Saline County, Kansas; Pinellas County, Florida; and Kane County, Illinois.

In a related development, the U.S. Department of Agriculture Animal and Plant Health Inspection Service (APHIS) recently reported four more H5N1 detections in dairy herds, raising the total to 46. All are from already affected states: two are in Michigan, with Texas and Idaho each reporting one more affected herd.

APHIS has also documented three more H5N1 detections involving wild birds, two of them from counties where dairy herds have been affected.