By the eighth day, a time when the three control monkeys infected with a common human flu virus were recovering, the experimental animals were so sick that they had to be euthanized. (sciencemag.org)
A pandemic strain could develop from H5N1 flu, either through reassortment with human flu viruses or through a long chain of person - to - person transmission. (discovermagazine.com)
The new flu, which has elements of pig, bird and human flu viruses in it, has been circulating for at least a month in Mexico. (scientificamerican.com)