When the birds catch the flu, it______.

The current strain of bird flu concerning the world, showed up in Hong Kong eight years ago. But avian influenza has a much longer history, including the strain that mutated into the deadly 1918 human flu pandemic. When birds catch the flu, it is usually a mild form that barely ruffles their feathers. But every once in a while, a virulent flu hits them, like the strain spreading worldwide that scientists call H5N1. Virulent avian flu was first recognized in Italy in 1878 and is extremely contagious. among birds and rapidly fatal, with death rates approaching 100 percent.