Something in the air

In August 1998, an extraordinary mission set off to the Arctic in search of clues, frozen into the permafrost, to a mass killer. Its members were looking for the bodies of seven young miners who died in 1918. It was not the great war that laid them waste, but influenza.

The pandemic of Spanish flu that raged across the world in 1918 took an estimated 40m lives. The mission to the Arctic was a serious bid to get hold of some genetic material from the victims of that disaster that could possibly stop such a pandemic next time. Because there will be a next time. That is one of the few things about influenza that is certain. There were three certified pandemics in the last century - in 1918, 1957 and 1968. The next one could occur any time.

When it happens, what some are now experiencing - headaches, limb pain, sweat-sodden nights and the feeling that there is nothing you want to do so much as curl up in bed and die fast - will sweep through offices and homes up and down the UK. Nobody will be immune - quite literally. A pandemic is caused by a new virus that catches everyone unawares and our bodies unprepared. There is a theory that man first caught flu after domesticating animals. To start a pandemic, the virus will have to be highly transmissible between humans. It will scythe down the population with no respect for age or fitness, although the first to die will be the most frail.

Liam Donaldson, the chief medical officer, says what we are now suffering is an epidemic of flu. It is impacting hard on an NHS which has cut savagely at inefficiencies until it has only enough beds to deal with the normal run of ill-health. Come a winter crisis like this, the whole system shudders with the strain.

But flu is never to be taken lightly. It is nothing like the common cold. It is one of the oldest diseases know to man, first described by Hippocrates in 412 BC. The first known pandemic was in 1580, although there are bound to have been some before. There have been 31 since.

The killing power of flu comes from the ability of the virus to mutate easily and rapidly. So there is not one strain of flu, but a multiplicity. The fact that you have flu one year does not stop you picking up a different strain the next. To complicate matters further, there are three forms: A, B and C. The one we fear most is A, but B can also kill. Even in a mild year, flu kills between 3,000 and 4,000 people. The elderly and the frail, such as those with heart or lung disease, are its chief victims. They die of secondary problems, such as bronchial pneumonia. The immunosuppressed and children with asthma are also vulnerable.

So far this winter, the public health laboratory service, which has always been considered the oracle on flu statistics, has said the figures are normal for the time of year. At the last count, 144 people per 100,000 were consulting their GP with flu. This week we will reach 200, the upper end of the normalcy bracket. At 400, we hit an official epidemic. But Donaldson, for reasons that may be to do with defending the government's stewardship of intensive care beds and talking up the pressure the NHS is under, reckons the figures are an underestimate. He is insisting that the real number - including those who phone NHS Direct for advice - is closer to 300 per 100,000.

One of the problems may be that this winter's outbreak seems to have hit the elderly particularly badly, in spite of the fact that the World Health Organisation's experts correctly predicted that the bug to fear this time was the Sydney strain of the virus. Every year, virologists have to make what amounts to little more than an educated guess as to which of the current viruses will cause trouble. Three of the strains can be incorporated into the vaccine that is then produced in large quantities worldwide and given to those most at risk.

They got it right. Sydney is the main culprit this year. But, said Dr Douglas Fleming, director of the Birmingham research unit of the royal college of general practitioners, the vaccine has not worked on everyone. "No vaccination is perfect. The older you get, the less perfect it becomes. The body has to mount a response to the vaccine. Older people don't necessarily mount a brilliant response."

This may have made things worse, but flu experts say the exact numbers don't matter. What counts is that the NHS is once again unable to cope. What, they ask, will we do when the pandemic arrives if we go to pieces every year once the flu season begins? We should be using each of these winter epidemics, year in, year out, as a rehearsal for the big one.

The World Health Organisation takes the looming pandemic so seriously it has urged every country to prepare its own emergency flu plan. Among the measures recommended are preventing public gatherings, such as sports meetings and concerts, imposing quarantines and closing schools. With vaccines having to be developed fast and therefore in short supply, countries may need to consider who should be vaccinated first: key personnel, doctors, researchers etc. So far, 12 countries out of 120 have done so, and the UK, to its credit , has two: one prepared by the Department of Health and the other by the Public Health Laboratory Service. They are strategies to plug the gaps when key people in government ministries, local authorities and essential services are falling like flies. A pandemic would have the potential to bring the country to a standstill. The plans deal with emergency vaccination programmes (although the first priority will be to isolate the new, deadly strain and try to develop a vaccine) and with ensuring supplies of flu drugs.

The frightening aspect of a pandemic is the unknown. We still do not know what made the 1918 flu strain so virulent. If we did, virologists might be more confident that we could prevent an outbreak on that scale again. That was why, in August 1998, Professor John Oxford of the Royal London Hospital and colleagues from the set off for the Arctic to try to unearth the secrets of the worst recorded outbreak by a long way. The number of deaths in the 1918 pandemic has been steadily revised upwards through the years, from 20m to the current 40m to 50m estimate. Some have speculated 100m. Samoa was the only country in the world unaffected. The more recent pandemics, in 1957 and 1968, killed only a few million each.

"The virulence of 1918 is the biggest unsolved mystery," says Oxford. "It is the holy grail. We hope the material we brought back is going to identify a particular genetic feature of the virus."

The men beneath the ice were aged between 18 and 29. They had arrived on the island of Spitzbergen late in September 1918, aboard a ship carrying Norwegian farmers and fish ermen to put in a winter's hard labour in the coalmines. But with them on the ship came the Spanish flu. Details of seven of those who died were recorded in a diary kept by the head engineer of the mining company. It was hoped that enough of the bodies would be preserved in the frozen depths beneath the permafrost to make it possible to deduce the genetic code of the virus within their tissues.

But when the dig began, it became clear that the gravediggers had themselves been terrified of the flu. Instead of burying the bodies in coffins deep below the permafrost, the bodies had been hastily wrapped in newspapers and thrust into shallow graves. Even so, there was enough left for the researchers to take 100 tissue samples from the miners' lungs, livers, kidneys, bone marrow and brains. "At the time it looked as though we wouldn't get much from the samples," said Oxford. "But we now have some virus signals. I hope it is going to identify a particular genetic feature of the 1918 strain."

A couple of outbreaks in recent years have had governments reaching for their emergency plans, convinced that the expected pandemic was beginning. The avian flu that broke out in Hong Kong in 1997/98 was one. A three-year-old boy was the first of several to be killed by the mystery strain. Eventually it was identified as the particularly virulent H5N1, which had never before been known to cross from birds into man.

There was serious anxiety around the world. Flu monitoring stations were working overtime. Experts flew out. But it eventually became obvious that each of the victims had been in contact with chickens - the little boy played with some at his nursery. After a mass slaughter of chickens, the flu strain disappeared. This virus had met one of the criteria for a pandemic - it was new to the human population - but it was not transmissible from human to human. The same thing happened last year with a flu strain that appeared from contact with pigs last year.

So we were saved yet again, but flu experts around the world are being vigilant. They have absolutely no idea when to expect the big one. They just hope that sufficiently effective and powerful flu drugs will be developed before a really mean virus spreads. And if Professor Oxford and colleagues can work out what it was about that Spanish flu that made it fell so many fit people so fast, perhaps the survival rate will be better next time.

Life under strain: the eternal fight against flu

• The catastrophic plague of Athens, in 430BC, may have been an early example of an influenza epidemic. But the virus only gained its present-day name in Renaissance Florence, a reference to the "influence" that the alignment of the planets was thought to exert on the occurrence of the illness.

• "Epidemics" are concentrated incidences of the virus within a limited region; "pandemics" refer to widespread concentrations of infection spanning several regions.

• The effects of flu pandemics can be utterly devastating - or relatively insignificant. There have been four this century: the Spanish flu pandemic of 1918 killed an estimated 40 m people, more than died in the first world war, but the 1977 Russian flu pandemic did not affect mortality rates greatly. In the US, Asian flu killed 70,000 in 1957 and Hong Kong flu killed 34,000 in 1968. A swine influenza pandemic among humans was predicted in 1976, after the virus infected large numbers of pigs, but it failed to materialise.

• Today, influenza kills between 3,000 and 4,000 people in a typical British winter. During the UK epidemic of 1989-90, though, there were nearly 30,000 fatalities.

• Epidemics continue to recur because there are so many varieties of the influenza virus - grouped into three strains - and because each one mutates so rapidly. Each year, new vaccines must be formulated to keep pace with the speedy evolution of the illness.