The Centers for Disease Control and Prevention (CDC) today unveiled a new influenza A wastewater tracker, part of its surveillance for H5N1 avian influenza, as three states reported more detections in dairy herds.
With the strong possibility that dairy cows can be spreading H5N1 asymptomatically and because testing in dairy herds has been spotty with delays in reporting, virologists and public health officials are looking at other ways—including wastewater testing—to gain better visibility on where H5N1 might be spreading.
Very few locations at the high level, but worth a closer look
The CDC launched the influenza A wastewater dashboard on its H5N1 monitoring page. It emphasized that current wastewater monitoring through its National Wastewater Surveillance System, which has more than 600 sites, doesn't distinguish the influenza A subtype or determine the source of the virus. Influenza viruses can come from humans, animals, or contaminated products such as milk.
In its interactive map, the CDC 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 CDC said it works with state and local partners to better understand factors that could be contributing to the levels.
Over the 2 most recent weeks, 230 sites from 34 states met the data reporting criteria, and three sites in three states were at the high level: Kansas (Saline County), Florida (Pinellas County), and Illinois (Kane County).
Marc Johnson, PhD, a virologist at the University of Missouri who has developed a probe to detect H5 in wastewater, said on X today that the CDC's dashboard is nice and that he's glad they're posting the information.
"I don't necessarily think that there needs to be a parallel H5 test run on every sample, but testing samples that are suspiciously high for it seems appropriate," he said.
Brian Wasik, PhD, a molecular biologist who is a research associate at the Baker Institute for Animal Health at Cornell University in New York, said on X that the CDC's dashboard will help shed light on baselines and longitudinal trends and what targets to explore.
H5N1 detected in 4 more dairy herds
In other developments, the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) today 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.
Also, APHIS reported three more H5N1 detections involving wild birds, two of them from counties where dairy herds have been affected. Detections in Michigan (Ionia County) and Idaho (Cassia County) involved agency-harvested birds, a rock dove and a black-billed magpie, respectively.
The other is a red-tailed hawk found dead in New York's Dutchess County. APHIS said all of the detections involve the Eurasian H5N1 subtype.
