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.

Bird flu hits Nevada as its effects remain visible at grocery stores. Susanne Rust hated to say it, but she did: “I think the H5N1 bird flu outbreak is going to continue to pest

Cases in avian influenza, better known as bird flu, are continuing to rise nationwide. In New York, the virus has primarily affected geese and raptors. But with one human death reported out of Louisiana,

The detection indicates that distinct forms of the virus known as Type A H5N1 have spilled over from wild birds into cattle at least twice. Experts said it raises new questions about wider spread and the difficulty of controlling infections in animals and the people who work closely with them.

The new strain, D1.1, is different from the strain, B3.13, that has been detected in other dairy herds throughout the country, but has been connected to serious infections in humans.

State officials say the highly pathogenic avian influenza – more commonly known as bird flu – is widespread in much of the state.

"I think the length of the road before [we see] a mutation that allows easier entry into our lungs is much shorter than people think."