Bird flu and SARS are both respiratory viruses and both can be fatal. Understanding their similarities and how they differ could help you prevent both these killer viruses.

Bird flu, SARS, the common cold and influenza are all viruses that multiply initially in your nasal passageways.

But the way bird flu and SARS are passed on is quite different at present.

SARS is passed directly from human to human.

You can catch SARS from any human being is infected with the SARS virus.

The bird flu (or avian influenza) is not currently known to pass from human to human.

You can only catch bird flu from an infected bird.

The great danger of bird flu is that it could mutate into a human to human "killer" virus which the general population would have very little resistance against.

A human to human bird flu virus could kill millions of people.

Estimates vary but credible sources like David Nabaro of UN health estimate the deaths will range from 5 to 150 million people worldwide.

The bird flu and SARS have one other similarity that is highly valuable in understanding how to prevent bird flu SARS even the common cold and influenza.

The most likely way bird flu and SARS will get into your body is when you touch the mucous membranes of your eyes or nose with infected hands.

So hand washing when you handle birds and eggs (in the case of the bird flu) and hand washing when you have contact with other people who could be infected (in the case of SARS) is the first line of defense against bird flu and SARS.

And avoiding contact between your face and your hands is highly recommended for bird flu and SARS prevention.

Natural soaps are recommended for hand washing - NOT antibacterial soaps - and it's also crucial you dry your hands thoroughly after washing.

Infections like the bird flu and SARS are passed more easily on wet hands.