Britain has the highest rate of allergy in Europe and the numbers affected are continuing to grow, outstripping the capacity of the NHS to care for them, specialists said yesterday.
Allergic reactions to substances including fruit, nuts, medical drugs and latex, which were once rare, are becoming common. Familiar allergies such as asthma and hay fever are growing. One in three of the population - equivalent to 18 million people - was affected by an allergy during his or her lifetime, ranging from the trivial to the serious, the Royal College of Physicians said.
A report by the college published yesterday warns of an alarming increase in serious allergies that can provoke life-threatening reactions. The commonest causes are foods such as peanuts and egg, bee and wasp stings, medical drugs and latex rubber.
Hospital admissions for serious anaphylaxis, a sudden and severe allergic reaction that leads to shock and collapse, have increased sevenfold in the past decade. Multiple allergies, in which sufferers react to a range of substances, have also increased.
Pamela Ewan, a consultant allergy specialist at Addenbrooke's Hospital, Cambridge and an author of the report, said: "This is not an increase in perception [of disease], it is a real increase. There is good data showing a doubling or trebling of allergic diseases over the last 10 to 20 years."
The causes of the increase are thought to be environmental changes acting on a genetic pre-disposition to allergy, which puts the British, with the New Zealand and Australian populations, as the most allergy-prone people in the world.
Cleaner homes and smaller families mean children are less exposed to bacteria and infections that help to educate their developing immune systems to identify and deal with invaders threats. They then over-react to substances that mimic the threat - proteins on pollen grains, house dust mites, cat and dog hairs - which trigger allergic reactions.
This theory, known as the hygiene hypothesis, was first advanced a decade ago and has been confirmed by many studies since. These have shown that children raised on farms with livestock have a third fewer allergies than those who are not. A second factor is thought to be the role of diet in pregnant women and infants. Those who consume low levels of antioxidants - fruit and vegetables - and high levels of fats and proteins are thought to be more allergy prone.
Stephen Holgate, professor of immunopharmacology at Southampton University, said different countries had different problems. In New Zealand, dust-mite allergy had been caused by the practice of laying new-born infants on sheepskins, which were breeding grounds for mites. But dust-mite allergy was almost unknown in Norway and Finland where the chief problem was pollen from birch trees.
"Taking an allergen away does not necessarily solve the problem. A new one steps in to take its place," he said.
The report calls for a big increase in the provision of allergy services in Britain. There are six main centres run by allergy specialists offering a full-time service and nine offering a part-time service. There are 90 clinics run by specialists in other disciplines who practise allergy medicine part time.
Dr Ewan said the inadequacy of the specialist service, which does not extend west of Bournemouth or north of Liverpool, was shown by the case of a man who suffered episodes in which his tongue swelled, culminating in a cardiac arrest. He was referred by his GP to a specialist allergy clinic but had to wait six months for an appointment before he was diagnosed with an allergy to a drug that was easy for him to avoid.
"He almost died ... It is extreme postcode medicine," Dr Ewan said.
She cited a second case of a 46-year-old man with hay fever who was unable to sleep or work in the pollen season. His GP gave him steroid injections twice a year to control symptoms, but over 14 years they caused his hip joints to crumble. He now has arthritis and is awaiting a double hip replacement. "He was referred to an allergy specialist - but 14 years too late," Dr Ewan said.
The growth of allergic reactions to fruit and vegetables is one of the most striking indications of a changing immune system. The cause is thought to be birch pollen the second most common cause of hay fever. Birch pollen shares proteins with fruit and vegetables, and allergies to the pollen are extending to include the food.
Serious reactions to drugs have increased sharply, with antibiotics, especially penicillin, aspirin, ibuprofen and other painkillers among the most likely to produce problems. These are distinct from side-effects that do not involve the immune system.
Allergy to latex rubber was almost unknown before 1980, with only two cases described in medical literature, but 8 per cent of health workers are now affected by it. The cause is the growth in the use of latex, driven by fear of Aids in the 1980s and the need for tighter controls on spread of infection.
Peanut allergy has trebled in the past four years but was rare before 1990. One in 70 children is currently affected amounting to 160,000 and it is the most common food to cause fatal or near-fatal reactions. Fish, shellfish, egg and milk can also trigger anaphylactic shock. Hospital admissions for food allergy have increased fivefold in 10 years.Reuse content