New avian flu viruses send U.S. scientists scramblingThree highly pathogenic avian flu viruses that have infected poultry and wild birds in the U.S. Midwest appear unlikely to present a significant risk to humans. But the presence of the viruses in North America has scientists scrambling to understand their potential long-term threat. One of the viruses, H5N2, has already led to the slaughter of millions of turkeys and chickens, as commercial farms try to control the spread of the virus. No humans have yet become infected, but scientists say it is possible that someone in direct contact with sick birds might catch the virus, though it is extremely unlikely that an infected human could pass the disease on to another human. “Most of the time, these viruses don’t have human disease potential, but obviously you need to be very careful,” said Dr. Stephen Morse, an expert in emerging infections at Columbia University. “Nowadays, you can’t say anything about flu with certainty ” MORE