A woman and her daughter are frightened while ducks approach closely for food at an amusement park in Beijing, China, Wednesday, April 3, 2013. Scientists taking a first look at the genetics of the bird flu strain that recently killed two men in China said Wednesday the virus could be harder to track than its better-known cousin H5N1 because it might be able to spread silently among poultry without notice. The bird virus also seems to have adapted to be able to be able to sicken mammals like pigs.
Section:Photo
