According to an article by the New York Times ("'Window is Closing' to Halt the Outbreak of Bird Flu"), H5N1 infections have been reported in nearly 200 cattle herds in 13 U.S. states. Genetic studies indicate that this outbreak resulted from a "spillover of the virus from birds into cattle..."
Concern is being expressed by some public health officials that "the window is closing" on the ability to prevent the U.S. cattle industry from becoming a long-term reservoir of the virus. At present, the virus does not easily jump to humans, but the concern is that this development would increase the chance of a mutution of the virus that makes human spread easier.
The article reports that the Department of Agriculture has established a system to encourage farmers to participate in investigations and has established a program of voluntary testing. But some public officials are claiming that this is not enough and are suggesting more extensive regulation of these risks.