EDP column by Dr Ketan Dhatariya

“My son has got eczema and I have hayfever. My doctor tells me we are ‘atopic’. What does that mean?"

To be ‘atopic’ means that you and your family have a genetic tendency to develop allergic diseases, such as asthma, eczema and hayfever. The word is derived from the Greek ‘atopos’ meaning ‘out of place’.

Atopy involves the production of an abnormal immune response to common environmental substances. Your immune system is present to help fight off bugs. If (for example) you inhale a bug up your nose, your body recognises that bug as not being part of ‘you’. Your immune system produces antibodies to those bugs. These antibodies latch onto the bugs and destroy them. In some individuals the immune system can produce antibodies to things that do not normally cause an allergic response – such as house dust mite, insect venom, grass pollen, latex and so on. Things that induce an allergic response are called allergens. The response to these allergens can be in the form of symptoms you may be familiar with, such as a runny nose, watery eyes common with hayfever. For those with contact dermatitis, they may get raised red or itchy skin with blisters. A common skin allergy is to the metal nickel found in belt buckles.

It can be quite difficult to formally diagnose atopy, but it is usually made on the history you tell your GP. There is a complex relationship between genetic and environmental factors contributing to the adverse reactions to these allergens. A family history of atopy remains the most useful way of identifying infants at risk of atopy. Early exposure to cows' milk, egg protein, peanuts, and other food allergens can lead to food allergy or atopic dermatitis in later life. Another example of this is thought to be exposure in early life to air borne allergens, in particular house dust mite, that can further contribute to the development of asthma in later life.

As with almost everything, prevention is better than cure, and helping to prevent allergies can start in infanthood. This is possible by breast feeding. This has been shown to reduce the chances of developing any of these conditions.

In severe cases of allergy, the reactions can precipitate difficulty in breathing due to the lung airways becoming narrower requiring the drugs often used in asthma (bronchodilators). Occasionally these do not work and it may become necessary to carry injectable epinephrine (adrenalin) as a kit. Extra protection can come from wearing or carrying an emergency medical notification to the allergy. These measures can be lifesaving and cannot be overemphasised.

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