Bird flu is creeping toward human transmission − how ... it becomes evident that H5N1 is displaying a common pattern of stepwise invasion from animal to human populations. Like many emerging ...

One year ago, the first bird flu infection in a human in the United States was reported in a Texas dairy worker. There have been at least 70 cases since then.

Bird flu, also known as avian influenza, is a virus that can sometimes spread from infected animals, like birds and cows, to humans, according to the Cleveland Clinic.

The H5N1 bird flu has been spreading widely among wild birds, poultry and other animals around the world for several years, and starting early last year became a problem in people and cows in the U.S.

At the viral chatter stage of an outbreak, pathogens are just starting to infect people in sporadic bursts. It's a sign that a pandemic may be on the horizon.

More than 500 bird species could go extinct in the next 100 years because of climate change and habitat loss, researchers ...