A deadly influenza virus has circulated widely in birds in recent years, decimating flocks but rarely spreading to humans. Nonetheless, because of its persistence in bird flocks, this highly pathogenic virus has loomed as a major public health threat. Seasonal influenza kills less than 1 percent of the people it infects. In contrast, human infections with the H5N1 virus, though exceedingly rare, are fatal in most cases. Should this virus mutate in a way that allows it to be transmitted as efficiently among people as seasonal influenza viruses are, it could take an unprecedented toll on human life.
A number of important scientific and public health questions regarding this virus remain unanswered, including the likelihood of such mutations arising and the mechanisms by which they may occur. Two recent studies co-funded by the National Institutes of Health (including research conducted by UW-Madison bird flu expert Yoshihiro Kawaoka) have shed light on how this potentially grave human health threat could become a reality.