Allergic disease accounts for 10 per cent of the GP prescribing budget and the incidence of asthma has reached epidemic proportions. So what lies behind the epidemic? Allergies do tend to run in families, but this cannot be the explanation for why there has been such a huge surge in the number of sufferers. Doctors now believe that our environment, and our affluent lifestyle, is to blame.
Have we all become too clean?
One theory is that good hygiene may actually be making allergies worse. Experts point out that countries with a high standard of living also have high levels of allergies. Third World countries, on the other hand, have hardly any allergies at all. Before the Berlin wall came down, East Germany had very few cases of allergies, despite the fact that its air quality was poor due to heavy industry. Since reunification, however, allergy levels have soared. Some experts believe that a sanitised world, where children grow up exposed to fewer infections and less dirt than previous generations, may be partly responsible for the epidemic.
“Children need to be exposed to dirt and contaminants so that their immune systems can be challenged,” says Maureen Jenkins, an allergy nurse consultant based in Sussex. “If the immune system has nothing to do, it will start to overreact to normally harmless substances.”
This view is backed up by research that shows that children who grow up surrounded by animals on farms are less likely to develop eczema, rhinitis, (which is similar to hay fever), and asthma. First-born children are also more likely to have allergies. This could be because younger brothers and sisters are exposed to more dirt and bugs which their older siblings bring home.
The soaring caesarean birth rate may also be contributing to the epidemic. Children born naturally are also less likely to develop allergies. “Natural birth seems to be protective because babies in the birth canal swallow microflora which help to boost their immune systems,” says Maureen Jenkins. Caesarean births are relatively sterile procedures and the baby is not exposed to the same kind of good bacteria.
But that is not the entire story. Cleaning products may be sparking allergic reactions too. “We are exposed to many different types of chemicals every day in the home,” says Professor John Warner of the University of Southampton. “The kitchen may be sparkling but we have not evolved to deal with such a bewildering array of contaminants.” Professor Warner is also looking at the effect of diet on the immune system. Certain types of fatty acids, found in fish oil, may help to protect against developing allergies because they change the immune response. “Nutrition does seem to affect the immune response, even before birth,” he says.
Are we not clean enough?
On the surface, it seems that we have never been cleaner. Our homes sparkle and we enjoy carefully controlled temperatures behind double glazed windows. In fact, centrally heated homes with wall to wall carpeting are perfect environments for mould and house dust mites, two of the major causes of coughing and wheezing. Asthma is now estimated to affect 3.4 million people in the UK. According to Professor Sarah Gurr of Oxford University, the rise of allergies may be directly connected to the fact that our homes are not clean enough. “Many houses look clean but they are full of fungi,” she says. Mould thrives in the perfect humid conditions which are now considered the ideal home environment.” Microscopic mould helps to break down skin particles in household dust. House dust mites then eat the leftovers. Their droppings contain a protein, which can provoke an allergic reaction.
Double glazed windows just add to the problem because they limit ventilation and lock moisture in. Draughty houses are actually less likely to cause illness due to allergies.
Many carpets and materials used in household objects contain volatile chemicals, which can irritate the skin and the lungs of susceptible
people. Eczema, when the skin becomes red and inflamed, affects one in 12 adults and one in eight children. “We are flooding our environment with chemicals,” says allergy nurse, Maureen Jenkins. “We know that exposure to large numbers of chemicals can trigger off chemical intolerance.” Although research has shown that living with many animals is protective against allergy, living with only one pet has the opposite effect. One in three UK households now has a cat. Hamsters, rats and mice may be cute but their saliva and urine contains an irritant protein, which is carried in the air. “Children are sleeping while their pet hamster is scurrying around in its cage. The air is full of allergens. No wonder, many of them develop a wheeze,” says Maureen Jenkins. She advises parents to take steps to minimise their children’s exposure to allergens and triggers. Skin prick test can also help to identify food allergies before they become a problem. The most common food allergies affecting children are sensitivity to cow’s milk, soya, wheat, eggs and nuts. Avoiding common allergens during pregnancy may help to protect the unborn child.