When it comes to the potential of H5N1 avian flu, otherwise known as bird flu, picking up mutations that may lead to human-to-human spread, that "train has already left the station," warns one infectious disease expert.

The first case of bird flu in a human in Ohio has been reported, according to officials. A farm worker from Mercer County, Ohio, located on the state's western border along Indiana, came into contact with deceased poultry that was infected with the virus,

Two vets said they had no known exposures to animals with known or suspected bird flu, and one said they didn’t practice in a state where there were known bird flu infections am