"An unusual surge in flu viruses detected at wastewater treatment plants in California and other parts of the country is raising concerns among some experts that H5N1 bird flu may be spreading farther and faster than health officers initially thought.

In the last several weeks, wastewater surveillance at 59 of 190 U.S. municipal and regional sewage plants has revealed an out-of-season spike in influenza A flu viruses — a category that also includes H5N1.

The testing — which is intended to monitor the prevalence of “normal” flu viruses that affect humans — has also shown a moderate to high upward trend at 40 sites across California, including San Francisco, Oakland and San Diego. Almost every city tested in the Bay Area shows moderate to high increases of type A viruses."

Susanne Rust reports for the Los Angeles Times May 13, 2024. [2]