The virus spread by panic

Imagine it, just for a moment.

You have probably come across reports of people in Vietnam and Thailand dying from Avian (or bird) flu. Suppose it were to spread. Hundreds of people fall ill in Hong Kong. Many of them die. Then there are outbreaks in Canada, Germany, the USA and France.

Within a few weeks, the first case occurs in Britain - and in no time the pandemic spreads. Ordinary flu vaccinations have no effect, because this is a new strain of flu; and anyway, there's not enough vaccine to go around.

This disease doesn't just affect the old, the young and the ill - those usually most easily affected by flu. It strikes down old and young, sick and able-bodied alike.

The number of deaths begins to climb. As people start clamouring for non-existent (and probably useless) flu vaccines, local authorities begin to issue daily bulletins, urging people to remain calm.

A national emergency is declared, schools are closed, non-essential workers are advised to stay at home to stop the disease spreading, and army field hospitals are set up throughout York and North Yorkshire to help overflowing hospitals cope.

York races, football league fixtures and other sporting events are cancelled; transport is restricted; and the number of deaths keeps on rising.

A Doomsday scenario that is never going to come true? Yes, almost certainly. It is, after all, what many feared would happen with SARS and look how quickly that health scare fizzled out.

Flu has proved a global killer before, however, and may well do so again.

The most famous flu pandemic of all was perhaps that of 1918, in which between 20-40 million people died worldwide - more than were killed throughout the First World War.

Global outbreaks or 'pandemics' of flu, often involving new strains that may have passed into the human population from birds or other animals, are fairly regular. According to the Department of Health's Contingency Plan For Pandemic Influenza, the intervals between previous pandemics have ranged from 11-42 years. The last was in 1968/69.

That has led some newspapers to speculate that we are overdue for another pandemic - and that flu is a much greater risk to global safety than terrorism will ever be.

Is that true?

Dr Ebere Okereke, a consultant in communicable disease control with the North Yorkshire Health Protection Agency based at the York Science Park, manages not to laugh.

"I don't think I'm in a position to assess the risk from terrorism," she says. "But a flu pandemic is a risk that we are aware of and prepared for. That's the reason why we have an emergency planning system."

The Government has two contingency plans for dealing with an outbreak of avian flu in this country - one, drawn up by DEFRA, setting out a plan to contain a flu outbreak that was confined in bird and poultry populations; and one to deal with an outbreak of any new strain of bird flu that got into the human population.

The DEFRA plan is full of echoes of the last foot and mouth outbreak: mass slaughtering of birds on infected farms; declaration of infected areas where movement is restricted; banning of live exports; incineration of bird carcasses. As a spokeswoman for DEFRA put it succinctly: "stopping movement of animals and people and bio-security and all that blah".

Such draconian measures clearly wouldn't be acceptable for dealing with an outbreak of bird flu among people.

Instead, the Department of Health contingency plan talks of using vaccine to protect the population as far as possible, and then taking measures to slow the spread of disease. These could involve placing restrictions on travel, encouraging those with flu who don't need hospital treatment to stay at home, closing schools and banning large sporting and other events which would bring large numbers of people together and give the disease a chance to spread.

If the number of flu patients were to rise significantly, doctors could be brought out of retirement to help, hospitals might cancel all but the most critical of operations, the Army might be asked to set up field hospitals to help cope with the flood of patients, and health visitors and community nurses could be used to help look after less seriously ill flu patients in their own homes.

But would it be enough?

Almost inevitably, Dr Okereke says, vaccines and other new anti-virals would not be at the forefront of the fight against the disease.

They might be given to some key personnel such as health workers and members of the emergency services. But they would be in short supply and may well not even be ready in time. A pandemic could arrive in the UK quite quickly after a new flu virus first broke into the human population abroad, she points out - and it can take up to six months to develop vaccines effective against a new strain of flu.

Instead, the main thrust of any effort to control the disease would involve restricting movement, isolating those with flu at home or in hospital, and trying to manage any panic by regular media briefings and public statements.

The situation would be constantly monitored, Dr Okereke says, and decisions on what action to be taken locally and regionally - for example, close of schools or cancellation of sporting events - decided accordingly.

What would not happen, however, despite reports in some of the national media, would be mass evacuations of whole cities. "Where would you evacuate people to?" Dr Okereke asks.

And while people might be encouraged to stay at home, there would be no question of army-enforced quarantines. The Army may be asked to help by providing logistic support, setting up field hospitals and so on, Dr Okereke says. "But there will be no quarantines and it is not going to be about shooting people!"

That, it seems, only happens in science fiction films. And media scare stories.

What is Avian flu?

AVIAN flu is a contagious disease caused by the influenza A virus, which is similar to the human influenza A viruses that affect thousands of people in the UK every year.

The Avian flu virus spreads between birds through airborne droplets or by contact with contaminated droppings. Occasionally, it can pass from birds to people, as seems to be the case with the outbreak in Vietnam and Thailand.

Since this time last year, there have been 52 cases altogether of bird flu in people in the two countries, the World Health Organisation reports. Thirty-nine of those people have died.

Most of the cases are thought to have involved people becoming ill after being infected by birds, possibly as a result of eating or coming into contact with raw poultry.

Generally speaking, however, it is difficult for the disease to spread directly from birds to people, the Department of Health says, so cases of bird flu in people are rare and isolated.

Therefore, the risk of avian flu reaching the UK in its current form remains low. What really causes concern is the possibility that a new form of avian flu virus could emerge - one that could be spread from person to person.

There is so far no "concrete evidence" that bird flu is being spread directly from one person to another, the World Health Organisation says.

The main source of infection in Asia during the latest outbreak has been from poultry. And in the outbreak of bird flu in Hong Kong in 1997 in which six people died, those who fell ill are thought to have picked up the disease from contact with poultry on farms and in live poultry markets.

That does not rule out the emergence in the future of a new strain of bird flu spread directly from person to person. It is known that avian and human flu viruses can exchange genes when a person or animal is infected with both viruses at the same time, which could lead a new, infectious strain emerging.

"The possibility that the virus could mutate into a form capable of spreading easily from person to person heightens the risk of a global epidemic," the Department of Health says.

Why are new strains of flu so dangerous?

OVER long periods of time, the population has built up immunity to familiar flu strains that regularly circulate among people. That is why, except among the elderly, very young or frail, they tend to cause nothing more than unpleasant symptoms.

If new strains of flu appear in the human population, however, we have no immunity to them. "Since the population has no immunity to the new virus subtype, it can appear as a serious life-threatening disease," says the World Health Organisation.

What is a pandemic?

A pandemic exists once human infection with a new virus strain has been confirmed and a high rate of infection and "rapid international spread" has been observed.

There are five 'phases' in the emergence of a pandemic, according to the Department of Health's Contingency Plan For Pandemic Influenza:

Phase 1: emergence of a new virus strain, possibly in the Far East

Phase 2: flu outbreaks caused by the new strain occur among people in foreign countries

Phase 3: new virus strain identified in the UK

Phase 4: pandemic influenza in the UK

Phase 5: pandemic dies away.

Typically, the Department of Health says, new flu viruses have emerged in the Far East and have spread along trade and transportation routes. Previous pandemic strains of flu - such as the 1918 pandemic - have spread worldwide in about six months.

Updated: 11:32 Wednesday, January 26, 2005