Bird flu is already aggressively lethal but scientists have now engineered a version of H5N1 that can be transmitted atmospherically, and with devastating results. This controversial research has not only divided the scientific community but also enraged global security agencies concerned about bioterrorism. "There's no way of saying how many humans would die. [The Spanish flu of 1918] killed 100 million human beings with a 2% kill rate. So jump to the age of globalisation, and imagine a 50% kill rate, says Laurie Garrett, a Pulitzer Prize winning science writer. Some believe that the benefits of further understanding such bugs far outweigh any imagined threats and people like Dr Vincent Racaniello, a world renowned virologist,"think that much of the rhetoric is alarmist and overblown". At the moment there's a tense truce between the camps but inevitably the research projects will publish their work. For some experts it's also possible that a super bug will one day escape the lab and go to work on an unprepared world. So is it just a matter of time before an outbreak of a devastating global pandemic?