3.24.2006

On Bird Flu & Person To Person Transmission

From Red Herring:
Scientists said Thursday they have pinned down why the H5N1 bird flu virus has trouble jumping from person to person, even though it can replicate efficiently in human lungs.

Currently, nearly all the 184 cases of H5N1 human infections, which have led to 103 deaths, have occurred because people picked up the virus from birds.

The virus has the potential to become a pandemic strain if it develops the ability to move easily between people in their coughs and sneezes, for instance, much like seasonal influenzas.

Published in the journal Nature, scientists from the University of Wisconsin, Madison and the University of Tokyo, Japan, have found that H5N1 needs to replicate more in cells higher up in the airway to make this possible.

The human viruses responsible for seasonal flus and the deadly H5N1 bird flu virus bind to slightly different versions of the same molecule. Found on the surface of cells which line the airways of the lungs, this molecule seems to hold the key to the development of a pandemic strain.

The version bound by common human flus tends to be found higher up in the respiratory tract, whereas the version of the molecule bound by H5N1 occurs in the air sacs located at the deepest part of the lungs.

Put simply, the higher up in the lungs the virus replicates, the better chance it has of being carried out of the lungs in a cough or a sneeze.



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