First described in 1878, what we know now as avian influenza has become a threat to domestic and wild birds and mammals worldwide. But how does it spread, and why is it so difficult to control?" The disease ‘Fowl plague’ was first described in 1878. But this was long before the cause had been identified. It wasn’t until 1930 that an influenza virus was isolated from a pig infected with swine influenza. This type of virus, the influenza A virus, is now known to be the cause of fowl plague or as w