More than 70 percent of California’s dairy cow herds are infected with bird flu. Here’s what to know

A dozen more dairy herds in California have been stricken with bird flu as the virus continues to infect animals and humans around the U.S.

Nearly 700 herds in the state — or 71 percent of all herds — have caught H5N1 since late August, forcing Governor Gavin Newsom to declare a state of emergency and the government to announce new testing.