A flu primer
Influenza is a potentially serious respiratory disease caused by a family of viruses
In the UK influenza affects most people during winter – hence ‘seasonal influenza’. How serious seasonal influenza is depends on which particular strains of virus happen to be circulating.
Periodically, in addition to seasonal flu, major outbreaks (or pandemics) of flu occur, based on novel strains of virus. These can be much more deadly than seasonal flu, as in the 1918 Spanish flu pandemic, although the last pandemic (H1N1 swine flu) in 2009 was relatively mild.
Other species, such as birds, have their own types of influenza virus. These can cause serious disease in humans. But human infections with avian viruses are rare and occur through contact with birds – these viruses are not transmitted between people.
If an avian flu virus did start to be transmitted between people, the consequences could be very serious indeed.Lead image:
Anna Tanczos/Wellcome Images CC BY NC ND