Man’s greatest enemy cannot be seen, it cannot be heard, and it is so small that billions, yes billions, will fit onto the head of a pin. As you read this, the enemy is massing for an attack. Many billions, many trillions of these beings are busy trying to find the key so that they can infect you. A few have already succeeded but at that point in their evolution it was not easy for a human being to get infected and the virus, known as H5N1 but more commonly called bird flu, was very alien to human physiology. This resulted in a very high death rate – in excess of 50% of those infected in the very early days.

As the virus continues to evolve there is hope, based on past experience, that as it becomes more adaptable to human beings it will become less deadly.

In 1918 an ancestor of this virus, H1N1 by name, launched a mass attack on us and killed up to 100 million people. I cannot be precise, as in 1918 records were not kept as carefully as today, and this virus hit as the Great War ended and confusion reigned. But the UK National Health Service puts the death toll at 50 million and that does not include those who were misdiagnosed or those who were killed in the resulting panic or as a result of the disruption of vital services.

In 1918 we did not even know what a virus was and it is tempting to think that this time round we will be ready. But the sad fact is we are not. There is no effective vaccine in place and there cannot be until we know what form the virus will take when the pandemic starts. We could spend millions producing vaccine but then we might find it is useless. Some might say we should anyway and that is something I will touch on later.

But are there not anti-viral drugs? Yes, these do exist but Tamiflu, which seems likely to have most effect, is in very short supply. It is also in high demand - it is available on the internet but at over $600 for five packs of ten – usual price from Roche, around $20 per pack!

The effectiveness of Tamiflu is aslo suspect with resistant forms of the virus already in place. The more Tamiflu that is used the more resistant strains will appear. Similarly as millions of birds are vaccinated the virus has more and more "experience" and learns to bypass these enemies.

But do not despair, there is plenty that you can do and I will cover this in future articles.