THE incidence of asthma and allergies is rising rapidly and the most likely cause is our Western lifestyle. A changed diet, increased exposure to chemicals and pollutants and a near sanitised way of life that protects us from germs have joined to make us susceptible to these chronic ailments.
The advances in biochemistry and our growing understanding of genes and the substances that they produce may lead however to vaccines that will eliminate the annoyance of hay fever or the frightening experience of an asthma attack.
About half the population of a typical OECD country is affected by allergic diseases, according to Prof Stephen Holgate of the University of Southampton. He warns that these diseases will become the norm and cause further illness unless researchers can learn what drives these ailments.
He was speaking yesterday on the closing day of the British Association for the Advancement of Science's annual Festival of Science, held this year in Sheffield. Humankind was the author of these afflictions, he said brought about by a changed lifestyle and changed environment.
"Of considerable concern is the progressive increase in the incidence of allergies, not only in the developed but also the developing world," he said. "A century ago allergies were almost unheard of , yet now almost half of the population, when tested against common allergens, demonstrates an allergic response."
While the rising trend in asthma and allergies was well established in western countries, incidence was also climbing in those countries which are adopting a western lifestyle, he said. What happened during the allergic response was clear, he said. Allergies and the symptoms associated with asthma are caused when the body over-reacts or becomes sensitised to substances that are usually not in themselves a danger. Common allergens included pollen, droppings of house dust mites, fungi and fur from domestic pets.
Exposure in some individuals triggers a massive and inappropriate response by the immune system, which reacts as though it were under attack by disease-causing organisms. The result varies but can deliver symptoms of a severe cold, skin rashes and in asthma, constriction of the tubes which deliver air to the lungs. Once sensitised the person's immune system will deliver a similar response every time the allergen is encountered.
There was also a very clear genetic component to allergies, Prof Holgate said. There was a very high incidence of asthma found in some restricted and inbred populations such as on Tristan da Cunha and amongst the Amish and Hutterite populations in North America. A genetic susceptibility along with exposure to allergens can in turn lead to an allergic reaction, he said.
There was no cure for allergies, and only the symptoms and not the cause could be treated. There was some optimism, however, that new scientific discoveries related to the complex biochemical processes linked to the allergic reaction might lead to anti-allergy vaccines. "A clear understanding of the cellular and molecular mechanisms of allergic disease is almost certainly going to lead to entirely novel treatments. High on this agenda is the introduction of vaccine strategies," Prof Holgate said.
