So why the 3 different names?
Are these the 3 different types of Bird Flu that I refer to on other pages?
Not at all...

"Bird Flu" is the term that is popularly used in the media. It is the layman's term.
It correctly conveys the meaning that the infection involves birds somehow, but fails to distinguish between the important 3 real variations that we have explained.
Please do read our page "3 Different Types" so that you do understand what is going on...

"Avian Flu" is exactly the same. The media just coined the name Bird Flu because they assumed that many ordinary people might not understand that avian means from birds...

"H5N1" is the technical name for the particular strain of the Bird Flu virus that is posing the current threat.
The flu virus is like the Common Cold virus in that it juggles its genes around on a regular basis.
That is why it is so difficult to vaccinate against it - it keeps changing!
The Influenza virus contains components that biologists had previously labeled "H" and "N", and the new strain is simply a combination of the specific mutations H5 and N1.
It is the first time that this combination has been around since 1918, which is why none of us have any natural immunity to it.

Here is some technical detail if you are interested:

Genetic structure and related subtypes

H5N1 is a subtype of the species Influenza A virus.
Like all other influenza A subtypes, the H5N1 subtype is an RNA virus .

HA codes for haemaglutinin, an antigenic glycoprotein found on the surface of the influenza viruses and is responsible for binding the virus to the cell that is being infected.
NA codes for neuraminidase, an antigenic glycosylated enzyme found on the surface of the influenza viruses. It facilitates the release of progeny viruses from infected cells.
The haemaglutinin (HA) and neuraminidase (NA) RNA strands specify the structure of proteins that are most medically relevant as targets for antiviral drugs and antibodies .
HA and NA are also used as the basis for the naming of the different subtypes of influenza A viruses. This is where the H and N come from in H5N1 .

The N in H5N1 stands for Neuraminidase, as depicted in this ribbon diagram.

Influenza A viruses are significant for their potential for disease and death in humans and other animals.
Influenza A virus subtypes that have been confirmed in humans, in order of the number of known human pandemic deaths that they have caused, include:

• H1N1 , which caused " Spanish flu " (1918 - 1919) and currently causes seasonal human flu ***
• H2N2 , which caused "Asian flu" (1957 - 1958)
• H3N2 , which caused "Hong Kong flu" (1968 - 1969) and currently causes seasonal human flu
• H5N1, the world's major current pandemic threat (2006)
• H7N7 , which has unusual zoonotic potential and killed one person
• H1N2 , which is currently endemic in humans and pigs and causes seasonal human flu
• H9N2 , which has infected three people
• H7N2 , which has infected two people
• H7N3 , which has infected two people
• H10N, which has infected two people

For a fuller version of this section go to http://en.wikipedia.org/wiki/H5n1

*** The Spanish flu caused an unusual number of deaths because it, like H5N1 , caused a cytokine storm in the body. The virus infected lung cells, leading to overstimulation of the immune system via release of cytokine bursts into the lung tissue. This leads to extensive leukocyte migration towards the lungs, causing destruction of lung tissue and secretion of liquid into the lung, and making it difficult for the patient to breathe. Due to the nature of the infection, people with a normal healthy immune system were more susceptible to the disease, such as young adults compared to young children and the elderly.

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