Dutch researchers have created a virus in the lab that could wipe out half the human race.
The Erasmus MC team experimented with the H5N1 influenza virus - bird flu - and gave it a number of mutations designed to help it spread far more easily. The research was carried out in ferrets, which have a smilar respiratory tract to humans.
In its present form, H5N1 is highly lethal, but hard to transmit. It can't be spread from one person to another by sneezing or coughing. However, of the 600 people who have been infected worldwide so far, 60 per cent have died.
The new version created by the researchers, though, can be spread rapidly through the air. It was easty to create, needing only five mutations - and these could easily happen naturally, they say.
The team says its aim is to learn more about the virus in order to help prevent future outbreaks.
"We now know which mutations to watch for in the case of an outbreak and we can then stop the outbreak before it is too late," says researcher Ron Fouchier.
"Furthermore, the finding will help in the timely development of vaccinations and medication."
he says the virus is held in a special high security laboratory, and that the safety of the experiments has been monitored by an international team of experts.
However, others have expressed unease that such a virus should be allowed to exist at all. The research is currently under evaluation by the U.S. National Science Advisory Board for Biosecurity (NSABB), which will evaulate whether it should be published.