Why there's 'enormous concern' over the risk of bird flu spreading to humans
The World Health Organization has raised concerns about the spread of the H5N1 bird flu variant, which has an "extraordinarily high" mortality rate in humans.
Moderated by Tomas Kauer 
The World Health Organization has raised concerns about the spread of the H5N1 bird flu variant, which has an "extraordinarily high" mortality rate in humans.
