Chickenpox affects 90 per cent of people and at this time of the year is particularly prevalent. Commonly though of as a mild childhood disease, it now occurs more often in adults and can be dangerous- even fatal. Barry Nelson reports.

BACK in 1971, the Queen wrote to her Prime Minister Edward Heath complaining she had a ''ridiculous disease'' and was covered in spots. She was recovering from chickenpox.

Nine out of 10 people will get chickenpox, or 'varicella' as it is also known, at some point in their lives. Commonly thought of as a mild childhood disease that is more irritating than life-threatening, most of us have the same dismissive attitude towards it as did the Queen - but it can be fatal.

''Around 25 to 30 people die every year from chickenpox,'' says Professor Norman Noah, an epidemiologist at the London School of Hygiene and Tropical Medicine. The number of deaths has increased since the 1960s. Between 1967 and 1977, 120 people died from chickenpox, between 1986 and 1997, 269 died.

However, fatal cases of chickenpox are comparatively rare. For most people, contracting the disease is merely irksome, rather than dangerous.

Children between the ages of two and seven years are most likely to get it and the vast majority of them will just have a few days of feeling under the weather and trying desperately not to scratch the maddening, itchy spots.

The disease is at its most prevalent in early spring. ''It seems to have a seasonal pattern though we don't really know why,'' says Prof Noah.

Chickenpox is mainly spread by airborne droplets from sneezes and coughs, so it is common for outbreaks in nurseries or infant schools when the youngsters are coughing and spluttering over each other. If one gets it, they all tend to get it.

The most obvious symptom is the infuriatingly itchy rash that covers the body. The tiny red spots quickly develop into full-blown blisters, and the patient is infectious from two or three days before the rash appears until all the blisters have formed scabs.

It is fairly common for people to have scars after chickenpox because of the incessant desire to scratch, but applying age-old remedies such as calamine lotion to the skin does help relieve the itching sensation.

Trudy Norris, of the National Institute of Medical Herbalists, says there are other herbal remedies which help reduce the discomfort of the illness.

''Purple Coneflower is a very useful anti-viral herb which is good for treating many infections," she says. "Elderflower tea makes you sweat and helps bring out the fever and it tastes nice. And to help offset the risk of scarring, it is worth using a good vitamin E cream.'' Having regular baths is also soothing and helps prevent a secondary bacterial infection.

After a week or two of chickenpox, most children will be back at school and will never have to worry about the disease again - though one quarter of people develop shingles in later life as it is also caused by the varicella virus which remains dormant in the body after an attack of chickenpox.

''Nothing is absolute, but having chickenpox once usually means a person has a life-long immunity from contracting it again,'' says Professor Simon Kroll, a paediatrician at Imperial College London.

Because many parents know this and just want to get the disease out of the way, some of them hold 'chickenpox parties' - where parents make sure their children contract the disease by putting them in a room with an infected child. But Kroll does not recommend it.

''I can understand that people think we all get it, so children might as well get it sooner rather than later, but there is no reason to suppose you would get a milder form and it is not always a risk-free, benign disease.''

In fact, one in five chickenpox deaths occur in children, though it is potentially far more dangerous in teenagers and adults as complications such as pneumonia are more likely to develop. It can also be more severe in people with impaired immune systems such as those with HIV or who are on steroids to treat cancer. ''Pregnant mothers should also avoid anyone with chickenpox.

Dr Ian Holtby, consultant in communicable disease for Teesside, said special measures are taken at North-East maternity units to try to prevent heavily pregnant women or new-born babies coming into contact with chickenpox.

"Health care staff who work with pregnant women try to ensure they are immune to chickenpox. If they haven't had it when they were children, we get them immunised," says Dr Holtby. "We have to be very careful because new-born babies have an increased risk of developing severe, generalised chickenpox."

Under these rare circumstances, chickenpox can lead to potentially life-threatening conditions such as pneumonia and encephalitis in young babies.

Because chickenpox can be more than a harmless children's illness, some countries, such as America and Australia, have introduced a chickenpox vaccine. However, it is not yet available on the NHS.

Of course, widespread vaccination would reduce the number of chickenpox cases but some experts are worried that mass vaccination may lead to many more cases of shingles.

''This is an issue that needs to be resolved and weighed up against the undoubted benefits of a chickenpox vaccine,'' says Kroll.

Until any vaccine is made widely available in this country, chickenpox will remain a common feature of life in Britain.

''Because chickenpox can be quite dangerous in adults, it is quite reasonable that a patient should go and see a GP, but with children it's a question of personal judgement," says Prof Noah.

''In most normal cases, a GP can't do a great deal - you just have to sweat out the illness - but a GP can recognise when a patient is becoming seriously ill and needs to go to hospital."