As the deadly H5N1 strain of bird flu arrives in Britain, Nigel Hawkes, Health Editor of The Times, explains the facts about avian flu and the risks it poses
What is avian flu?
It is an infection that affects birds, caused by an influenza virus. It is easily spread, and varies widely: some strains cause little obvious effect, while others are usually fatal.
What does H5N1 mean?
The flu virus carries two proteins that form spikes on the surface of the virus coating: haemaggtlutinin (H) and neuraminidase (N). These vary from subtype to subtype. There are 15 different versions of