evidence: The current H5N1 bird flu outbreak has spread to cows at dozens of dairy herds in nine U.S. states. The U.S. outbreak was first reported among wild birds in 2022, and has infected more than 92 million birds. The first description of bird flu in history dates to 1878 in northern Italy and the H5N1 strain was first found in 1996 in southern China. Three human cases have been reported in this outbreak. Human cases of bird flu are rare, and no human-to-human transmission has been reported in the current outbreak.