Ten ferrets, some bird flu and swabs. That is all, according to a presentation last summer, one needs to concoct a virulent strain of influenza that could start a deadly pandemic among humans.

These initial findings were presented last September in Malta at the European Scientific Working group on Influenzameeting to an auditorium packed with fellow scientists and policy makers. Ron Fouchier, a virologist at Erasmus Medical Center in Rotterdam, himself a bit sniffly at the time, calmly explained that he and his team had discovered that without the help of another virus, the deadly avian flu (H5N1) could easily mutate in mammals to become transmissible through the air, like a true pandemic strain, through a sneeze or a cough. And it might need as few as five mutations to make that leap.