Ducks are fed by two tourists 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 ... more 
Ducks are fed by two tourists 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 virus also appears to have mutated into a form that enables it to more easily infect animals such as pigs, meaning they could serve as hosts that spread the virus more widely among humans. (AP Photo/Alexander F. Yuan) less 
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Associated Press | Photo By Alexander F. Yuan
Wed, Apr 3, 2013 5:57 AM EDT