Flu

Flu is caused by a virus

Flu and complications linked to it kill hundreds of people in the UK each year. But despite massive investment in research into the virus, there is no cure.

However, there are vaccines which have some protective effect. These are normally administered to the elderly and the vulnerable each year.

But every few years a new strain of flu appears which spreads so rapidly that precautions cannot be developed in time.

This can lead to pandemics which threaten millions of lives. The worst flu pandemic this century was the Spanish flu pandemic of 1918 which killed an estimated 40 million people - more than World War One.

What is flu?

Many people confuse flu with a common cold. There is a big degree of crossover between the two. Both are caused by viruses.

According to Cardiff's Common Cold Centre, the symptoms of a common cold include:

• A scratchy, sore throat;
• A blocked or runny nose;
• A cough.

Common flu symptoms include:

• Spells of high fever (hovering above 38.3C or 101F) and chilliness;
• Severe muscle aches and pains;
• Followed later by the traditional cold symptoms;
• Flu tends to have a more sudden on-set than a cold.

Both colds and flu tend to last for about five or six days in a normally healthy person and are transmitted in similar ways - cough, sneezing and fingers made dirty from being poked in the nose and eyes.

How to treat the flu

There is a temporary vaccine against flu and those most likely to benefit from it include the elderly, people with damaged immune systems and the very young.

These people are at greater risk of serious complications that can be fatal.

For the majority of people with flu, however, the symptoms can be treated with bed rest and over-the-counter drugs.

The most difficult symptoms to treat are aches and pains, high fever and a lingering cough.

Once a person has the flu, they should:

• Take paracetamol to treat the high fever and aches and pains;
• Take a linctus to treat the cough or drink lots of hot, sweet fruit drinks, such as hot lemon with honey;
• Because the fever causes sweating and dries out the body, patients should increase the amount of juices, water and hot drinks they take;
• Smoking aggravates the flu so patients should steer clear of smoky atmospheres;
• People with a high fever and muscle pain should rest in bed. This should relieve the aches and pains and will ensure the virus is not spread.

Antibiotics are not effective against flu viruses, but aspirins can be taken, although not by children with the flu.

This is because they could be at risk of developing Reye's syndrome, a neurological disorder which is linked to aspirin use by the young.

Antivirals are drugs which can be given to high risk patients who become ill with seasonal influenza and they are only effective if taken within 48 hours of onset of symptoms.

They are not a cure but and may help limit the impact of some symptoms and reduce the potential for serious complications.

Guidelines from the National Institute of Clinical and Health Excellence state they should only be used when the number of people with flu reaches a high level and there is good evidence that flu is "circulating in the community".

Secondary infections

For most healthy people influenza infection is nothing but an unpleasant experience.

However in the elderly or people with underlying chronic health conditions, such as heart disease, it can can lead to illnesses that are more serious.

According to the Health Protection Agency, the most common complications of flu are bronchitis and secondary bacterial pneumonia.

These illnesses may require treatment in hospital and can be life threatening in vulnerable individuals.

The influenza virus is not necessarily the cause of high mortality, but for old sick people it may speed up their death.

Epidemics

Scientists do not know why some viruses become mass killers, but recent research suggests a molecular mechanism may allow a virus to cause sweeping and potentially fatal damage to the body.

Normally influenza is confined to cells within the respiratory system, but some viruses have a unique key which unlocks the door to cells throughout the body.

The new discovery could allow doctors monitoring flu viruses to spot changes which might give a virus pandemic potential.

Influenza virus surface proteins alter frequently, requiring new vaccines to be developed to protect against them.

The viruses are never the same each year, but normally the surface proteins undergo slight changes.

More dangerous is a "shift" when two different viruses mix together to create a radically different strain.

This page contains only basic information about medical problems. If you are worried about a particular condition, consult your doctor.