First U.S. detection of virulent H5N9 strain, at a California duck farm, draws scrutiny as evidence of genetic reassortment that could trigger human outbreaks.

A new strain of bird flu has been detected in the United States, and it has sparked a lot of concerns among farmers and general population. Bird flu is a disease caused by 'avian influenza A virus' that usually spreads among birds,

US officials are investigating the appearance of a strain of bird flu identified in the US for the first time, a worrying sign that the virus is evolving in ways that could make it harder to