Changes Cited in Bird Flu Virus

Deadly Strain Acquiring Mutations Similar to Those in Reconstructed 1918 Virus

By David Brown
Washington Post Staff Writer
Thursday, October 6, 2005; Page A03

The strain of avian influenza virus that has led to the deaths of 140 million birds and 60 people in Asia in the past two years appears to be slowly acquiring genetic changes typical of the "Spanish flu" virus that killed 50 million people nearly a century ago, researchers said yesterday.

How far "bird flu" virus has traveled down the evolutionary path to becoming a pandemic virus is unknown. Nor is it certain that the much-feared strain, designated as influenza A/H5N1, will ever acquire all the genetic features necessary for rapid, worldwide spread.