Bird flu resistance in humans explained

Two groups of researchers, in Japan and in the Netherlands, have discovered why the avian flu virus is transmitted rarely if ever from one person to another.

The reason is simply that the cells bearing the type of receptor the avian virus is known to favor turn out to be clustered in the deepest branches of the human respiratory tract. Thus, the viruses cannot be spread by coughs and sneezes, as are human flu viruses, which infect cells in the upper respiratory tract.

The avian flu virus would need to accumulate many favorable mutations in its genetic material before it could become a pandemic strain, said Yoshihiro Kawaoka, a virologist at the both the University of Tokyo and the University of Wisconsin. According to a press statement he approved, "The finding suggests that scientists and public health agencies worldwide may have more time to prepare for an eventual pandemic."

full story:
http://www.iht.com/articles/2006/03/22/news/flu.php

Also see:
Bird flu's human-attack pathway revealed