HONG KONG: A virus that weakens the immune system of chickens is likely to have set the stage for the rampant spread of bird flu across Asia, a Hong Kong scientist said yesterday.
Frederick Leung, a zoology professor at the University of Hong Kong, said his studies conducted since 1996 showed that chickens here hit by bird flu were usually struck by the infectious bursal disease virus, (IBDV), about six months earlier.
