The X factor
One hundred years on from the Spanish Flu, the World Health Organisation has put scientists on alert for a deadly new strain named Disease X ... and factory farming could be to blame. Andreas Whittam Smith reports
Should you meet someone who, unfortunately, has developed a fever, become short of breath, whose face appears to be tinged with blue and is subject to vomiting and severe nose bleeds, you could wonder if Spanish Flu has returned 100 years after it first appeared in 1917-18, shortly before the end of the First World War.
For, according to Dr Jonathan Quick, chair of the Global Health Council, we are due another visit from this terrifying disease, which is said to have infected 500 million people around the world.
Dr Quick doesn't mince his words: "The big one is coming - a global virus pandemic that could kill 33 million victims in its first 200 days.
"Within the ensuing two years, more than 300 million people could perish worldwide.
"At the extreme, with disrupted supply of food and medicines and without enough survivors to run computer or energy systems, the global economy would collapse. Starvation and looting could lay waste to parts of the world."
And what is this "big one"? It is, indeed, Spanish Flu again.
Dr Quick says that the most likely culprit will be a new and unprecedented deadly mutation of the influenza virus. The conditions are right: "It could happen tomorrow."
Dr Quick explains that somewhere out there, a flu virus is boiling up in the bloodstream of a bird, bat, monkey or pig, preparing to jump to a human being. When it finds its way into a person, the resulting human strain can kill us more easily, because it is unknown to us and our bodies have zero immunity to it.
The scientist also argues that we have inadvertently developed a powerful way of helping influenza to kill us. This is our addiction to cheap chicken and pork - and the factory farm industry that supplies it.
Factory farms present one of the greatest potential origins of catastrophic disease, because they pack animals together by the million in conditions that can be fetid incubators of disease.
The consequences of the over-crowding of troops during what was to be the final year of the First World War are, indeed, part of the explanation for the outbreak of Spanish Flu.
While there is no unanimity about the location of the first examples, one influential inquiry pinpoints a major troop staging and hospital camp in Etaples, France, as being the origin of the 1918 flu pandemic.
It was also home to a live piggery, and poultry were regularly brought in from surrounding villages.
A British team, led by virologist John Oxford of St Bartholomew's Hospital, has argued that a significant precursor virus, harboured in birds, mutated and migrated to pigs that were kept near the frontline.
In other words, it was a perfect setting for the way viruses can leap between birds and beasts and human beings.
Flu begins to spread when an infected person sneezes or coughs. It is a simple as that.
No doubt, there was a lot of sneezing in the First World War armies.
Moreover, these soldiers are likely to have been suffering from malnourishment - given the absence of proper cooking in the trenches - from the stress of combat, naturally enough, and from the chemical attacks that were developed as a weapon of war at this time.
However, there were some oddities about the outbreak. For instance, the pandemic mostly killed young adults.
The American statistics are astonishing. In 1918-1919, 99% of pandemic influenza deaths in the US occurred in people under 65, and nearly half in young adults aged 20 to 40 years old, with particularly high death rates in pregnant women.
This is in sharp contrast to what one would expect; that the main sufferers would be the very young, or the very old.
Another strange aspect of the outbreak was that it seemed to be at its worst in the summer and the autumn, rather than in winter, its usual season.
But the big questions are, why was the death toll so massive and why were so many countries affected?
The figures are shocking. In India, as many as 17 million people died, about 5% of the population. In Iran, the impact was enormous. According to an estimate, between 900,000 and 2.4 million people died. Then came the United States, with 500,000 to 675,000 deaths. Brazil lost 300,000 as well as its President, Rodrigues Alves.
Then came France and Britain. In France, the toll was 400,000 deaths, and in Britain as many as 250,000 died.
Given that the two countries have broadly similar populations, could Britain's lower figure be attributed to the protection afforded by the English Channel and by the related fact that none of the fighting that took place during the First World War - mainly trench warfare with all its consequences for the spread of disease - actually took place on British soil?
Consider, too, the arithmetic of the pandemic.
About a third of the population of the world was infected. Of these cases, an estimated 10% to 20% died. In turn, this implies that some 3%-6% of the entire global population died.
These are incredible figures, even if historians calculate that the medieval Black Death was even worse. Estimates say 50 to 100 million people worldwide lost their lives from Spanish Flu.
It seems that a third oddity might explain the sheer size of the pandemic. There is something called a 'cytokine storm', which turns your own immune system against you, so a healthy immune system might actually hurt more than it helps.
It has been postulated that the strong immune reactions of young adults ravaged the body, whereas the weaker immune systems of children and middle-aged adults resulted in fewer deaths among those groups.
A second wave of the pandemic began to develop in August 1918. It began in France, Sierra Leone and the United States. More seriously still, the virus had mutated to a much deadlier form. As a result, the 13 weeks between September and December 1918 proved to be the costliest in lives.
We are still not done with the oddities. For this peak has been explained in almost Darwinian terms. In civilian life, natural selection favours a mild strain. For the mildly ill continue with their lives, preferentially spreading the mild strain, while those who get very ill stay at home.
But this pattern was reversed in the trenches. Soldiers with a mild strain stayed where they were, while the severely ill were sent on crowded trains to crowded field hospitals, spreading the deadlier virus.
The final oddity is how the pandemic suddenly eased quite dramatically.
We have the figures for Philadelphia in the United States. Some 4,597 people died in the week ending October 16, 1918, but by November 11, influenza had almost disappeared from the city.
It looks as if the virus may have mutated extremely rapidly to a less-lethal strain.
This is, apparently, a common occurrence with influenza viruses.
Now, there comes another forecast of a new deadly disease, which supports the dire warnings by Dr Quick quoted earlier.
The World Health Organisation (WHO) has put scientists and health workers around the world on alert for a new and potentially deadly pathogen, which it has named 'Disease X'. A pathogen is an infectious agent, such as a virus, or bacterium.
The WHO states: "Disease X represents the knowledge that a serious international epidemic could be caused by a pathogen currently unknown to cause human disease. History tells us that it is likely the next big outbreak will be something we have not seen before."
John-Arne Rottingen, a scientific adviser to the WHO, commented that it might seem strange to be adding an 'X', but the point is to make sure that we prepare and plan flexibly in terms of vaccines and diagnostic tests.
Mr Rottingen's chief fear is that Disease X could be sparked by a disease that jumps from animals to humans - just as Spanish Flu of 100 years ago seems to have done.
So, what conclusions should we draw?
We should consider pandemics as natural disasters, like hurricanes or forest fires. We cannot prevent their occurrence. Instead, we must consider how best to meet the consequences, among them a sudden increase in the demand for nurses, doctors and medical specialists along with hospital facilities.
If our public services can rehearse for a terror attack - as they do - they can also act out the best responses to a pandemic.