Health officials in Hong Kong are examining samples from a supposed outbreak of bird flu to see whether they represent a new strain of the virus.  The tests are being carried out in laboratories in Hong Kong and on the China mainland. The samples were taken from a group of approximately 60 chickens who died suddenly last week.  The cause is surmised to be some version of the H5 flu virus, because other versions are not so deadly.  The government is concerned that the virus may have mutated, requiring a change in the vaccine given to farm animals. More details...