Health systems will likely struggle to differentiate the virus from flu-like illnesses

If one can point to anything good about the H5N1 bird flu outbreak in dairy cattle — to be honest, there’s nothing good about this situation — it’s the timing. Transmission of the virus through U.S. dairy herds took off when last winter’s flu season was effectively over, making the job of looking for people infected with H5N1 an easier task in theory, though there have been plenty of human hurdles impeding those efforts.

But in the months since the outbreak was first detected, the spread of the virus in cows has not been contained, with infections reported in 339 herds in 14 states so far. Now, with cold and flu season looming, it is likely to become significantly more difficult for the country’s public health departments to track the virus.