With plunging temperatures, this is the time of year when the dreaded flu bug can strike the hardest.

So far, this winter has not seen an epidemic of influenza, but every year thousands of people die from the often underrated illness.

Nearly 80 years ago a worldwide pandemic of influenza killed an estimated 25 million people, ranking the virus alongside killers such as the medieval Black Death.

In a worrying development, doctors in Hong Kong have been baffled at the emergence of a deadly "bird flu" virus, which has killed four people.

An anti-viral drug has been located that is effective against the new strain, which is thought to have crossed over into humans from birds, possibly through the consumption of infected chicken.

So far the virus is confined to Hong Kong. It is being investigated by representatives from the US Centre for Disease Control and Prevention.

Dr Douglas Fleming, Director of the Birmingham Research Unit of the Royal College of Practitioners, which runs a flu surveillance programme, said that the last severe winter for flu in Britain was 1988/9 when there were an extra 20,000 deaths that could be attributed to influenza, bronchitis and pneumonia. Many of these could have been prevented by an annual flu vaccination.

So far figures for "flu and flu-like illnesses" this winter are "about average" in Britain and the rest of Europe, said Dr Fleming.

"It is always difficult to predict whether the situation will get more serious." But is likely that flu levels will increase as the winter progresses, he said.

In 1988/9 cases reached 600 a week per 100,000 people. An epidemic is judged as beginning at 400 cases a week. Current levels are hovering around 200 cases a week.

According to the National Health Service Confederation and the Royal College of Physicians, hospital services are so stretched in Britain that a flu epidemic this year would be disastrous.

Vaccination

Flu jabs have become much more widely available in the past 10 years, although they have been around since the 1960s.

Millions of sick and elderly people were advised in October to contact their GP for a jab that could prevent the virus.

In the past only half of those most at risk have come forward to be immunised. But Dr Fleming said: "on the whole, the jabs are getting to the right people."

Those in the at risk categories are adults or children with long term respiratory diseases such as asthma or emphysema, those with kidney failure, heart diseases, and those with suppressed immune systems, such as people with HIV.

The Department of Health has also stressed that all elderly people in nursing homes should be vaccinated because the virus can spread easily in such environments.

Each year the vaccination is constructed by a group of doctors from the World Health Organisation who meet in Geneva. They predict which particular strains of virus are most likely to be prevalent that year. They base their findings on laboratory reports from all over the world.

This current flu vaccine is designed to protect against the three flu viruses: A/Wuhan, A/Bayern, B/Beijing. It offers 60-80% protection against virus.

Nothing can protect against the many other viruses that produce the same symptoms as flu, which can include aching limbs, coughing, high temperature sore throat and feelings of fatigue.

But according to Dr Fleming, most people who catch flu, outside of the risk categories, experience a very minor illness.

"They may not even realise how ill they are until they are past the most infectious period," he said.

" The symptoms of flu in the early stages are a high fever and coughing but even doctors can find it impossible to distinguish between flu and other respiratory viruses, said Dr Fleming.

Caused by comets?

The influenza virus was discovered in 1933, by a team of doctors at London's National Institute for Medical Research.

The term "influenza" is said to have been coined in 15th century Florence where outbreaks were thought to be ordained by the stars. Even until quite recently comets were blamed for epidemics.

But the virus has been around for thousands of years. The pandemic of 1918-1919 killed roughly 25 million people. It was rife in the trenches of Northern France at the end of Word War I and eventually killed more people than the war itself.

In 1957 a flu epidemic killed one million people and in 1968, 700,000 lives were lost.

Back to top | BBC News Home | BBC Homepage	©