Flu pandemic

Seasonal flu, epizootic, avian influenza, bird flu, flu pandemic… Following are several definitions to provide a better idea of the different terms commonly used.

Avian influenza
Avian influenza is a flu viral infection that spreads between birds. It is due to a type A virus (Influenzavirus A). This virus family is itself divided into sub-types, which include the H5N1 virus. Within each sub-type, the virus regularly changes form.
This infection can affect nearly all species of birds, both wild and domestic.

Epizootic
An epizootic is an epidemic that only affects animal species.

Bird flu
Bird flu occurs when a human being is contaminated by an avian influenza virus through close contact with an infected bird.

Seasonal flu
Flu is an acute, contagious respiratory infection caused by the human influenza viruses.

Flu pandemic
A flu pandemic is a flu epidemic characterised by its rapid spread from human to human and over a wide geographical area, following the emergence of a new virus. Because the virus possesses new characteristics, the population’s immunity is low or zero. It can cause a high number of serious cases and deaths.

H5N1
Flu viruses have two characteristic structures: haemagglutinin (H) and neuraminidase (N). In nature, there are 16 different types of haemagglutinin (H1 to H16) and 9 different types of neuraminidase (N1 to N9). A virus is labelled according to the type of its haemagglutinin and neuraminidase. Humans are very sensitive to the H1N1 and H3N2 viruses. At present, they are less easily infected by the H5N1 virus, which conversely is highly pathogenic for birds.