A newer variant of H5N1 bird flu that recently infected dairy cattle in Nevada has a genetic change thought to help the virus infect mammals – including humans – more easily, according to a new brief from the USDA’s Animal and Plant Health Inspection Service.

The variant of bird flu that killed a Louisiana resident has now been found in dairy cows. Until now, the human cases of bird flu traced to cattle have been mild, mostly eye infections. But the U.S. Department of Agriculture confirmed that a strain previously found only in wild birds has turned up in dairy herds in Nevada ‒ raising concerns that future human infections could be more serious.