Scientists in the Netherlands have developed a new strain of bird flu, that, if released, could kill millions.
H5N1 - better known as bird or avian flu - can kill humans, but has not gone pandemic because it cannot spread easily among us, according to New Scientist.
But, this could
change - five mutations in just two genes have allowed the virus to spread between mammals in the lab. Despite the mutations, the virus remains just as lethal.
"The virus is transmitted as efficiently as seasonal flu," Ron Fouchier of the Erasmus Medical Centre in Rotterdam told New Scientist.
H5N1 evolved in poultry in east Asia and has spread across Eurasia since 2004. In that time 565 people are known to have caught it and 331 have died. During that time, no strain that spreads easily among mammals has developed, despite millions of infected birds, and infections in people, cats and pigs.
