The number of people suffering from the allergy in the UK is reported to be increasing - and children are particularly at risk.

Even a tiny trace of peanut dust can cause sufferers to develop severe itching, rashes and stomach problems.

Sometimes allergic reactions can lead to a potentially fatal fall in blood pressure.

US scientists from Johns Hopkins University in Baltimore say they took Arah2, the peanut gene thought to produce the allergic reaction, and mixed it with chistosan, a product made from crab shells and crustaceans.

They injected the vaccine into mice bred to be allergic to peanuts and found they were much less likely to suffer an allergic reaction than mice not given the vaccine.

They say the vaccine could be used to develop a similar treatment for humans.

It would aim to prevent people from becoming allergic to peanuts, rather than to treat those who are already allergic.

Accidental exposure

Writing in Nature Medicine journal, the scientists, led by Kam Leong, say: "Given that the only treatment of food allergy is complete avoidance of all allergen-containing food products and often involves aggressive emergency treatments, pre-immunisation may be a viable therapeutic tool."

Around half of all allergic attacks caused by peanuts come about through accidental exposure.

Peanuts are widely used in a variety of products and it can be hard to know which foods contain them.

If a person suffers an attack, rapid treatment with epinephrine can reduce the severity of the attack, but it will not prevent a future attack.

The Anaphylaxis Campaign, which has around 5,000 members, says 80% of people with allergies suffer a reaction to peanuts or peanut oil.

One in 200 children is estimated to have a peanut allergy and up to 2% of the population has a severe allergy.

There is no general agreement why the number of people who suffer from peanut allergies is increasing.

But the campaign says there are various theories.

For example, there are more nuts around now, nuts are introduced to children at an early age and foetuses are sensitised to nuts in the womb because their mothers are eating more of them.

Moira Austin of the campaign adds that it could be that society's increasing obsession with cleanliness is leaving people's immune systems with nothing to react against, causing them to go "haywire" and react against "safe" products.

The campaign says many foods contain nut products, particularly cereals and sweets, and there is a danger of cross contamination on the production line.

Some parents ring the campaign in tears because they cannot find products for their allergic children to eat.

The campaign believes manufacturers are becoming increasingly worried about being sued over peanut allergies and are covering themselves by placing warnings on a host of products.

Ms Austin says manufacturers need to think of separating their production processes to ensure nut products are produced in segregated areas of factories.