Although avian flu viruses have infected humans in the past (often with lethal effect), so far, these infections have come directly from birds. Over this past summer, however, researchers presented disturbing results at a scientific meeting. By growing the avian H5N1 virus in mammals for several generations, they had evolved a strain that can spread among mammals (ferrets, in this case) simply through the air. Additionally, researchers identified the mutations that enabled the virus to do so--the kind of information that would be enough to allow any competent molecular biologist to create an exact duplicate.

Like any scientists, these ones want to publish their results, but that's where things are getting messy. The US National Science Advisory Board for Biosecurity has asked both Nature and Science to "delete details regarding both scientific methodology and specific viral mutations before publishing." The journals recognize why the NSABB is concerned, but they also both feel that responsible researchers will need to know these details if they're to effectively study the risk of an H5N1 pandemic.

Currently, both have issued statements that they're considering the requests, but haven't yet decided how to proceed.