News Life Bird flu less deadly, but more widespread, than official numbers suggest Survey finds 1 to 2 percent infection rate in affected populations By Tina Hesman Saey February 23, 2012 at 4:22 pm - More than 2 years ago Share this:Share Share via email (Opens in new window) Email Share on Facebook (Opens in new window) Facebook Share on Reddit (Opens in new window) Reddit Share on X (Opens in new window) X Print (Opens in new window) Print The deadly H5N1 avian influenza virus may not be quite so lethal after all, an analysis of more than 12,000 blood samples suggests. Since 2003, the World Health Organization has recorded 573 cases of humans infected with bird virus.