Bird flu may mutate to kill more than 50% of humans who catch it

Bird flu could mutate to become even more harmful to humans due to the ongoing unprecedented outbreak, experts fear.

Cases of the killer H5N1 strain, which are at record levels, have already jumped from birds to foxes, otters and mink.

It has sparked huge concern among top virologists that the deadly pathogen is now one step closer to spreading in humans — a hurdle which has so far stopped it from triggering a pandemic.

The World Organisation for Animal Health (WOAH) has now warned mammals could act as 'mixing vessels' for different influenza viruses, potentially unleashing a new variant that could be 'more harmful' to humans.

The H5N1 strain already has a fatality rate of around 50 per cent among people.