Updated 23 March 2018

Can doctors predict allergies?

Identifying allergy sufferers as early as possible may help to avoid extreme situations like anaphylactic shock and even death.

Millions of people worldwide are affected by allergies.

We can be allergic to things we touch, inhale or eat. When we’re allergic to something, our immune system mistakenly believes that the substance is harmful to our body and launches an attack.

An increase in food allergies

Fortunately true allergies are relatively rare, and according to a study published in The Journal of Allergy and Clinical Immunology less than 4% of the American population have a true allergic reaction to one or more foods.

An allergy can be just a nuisance, causing reactions like runny or congested noses, hives or digestive issues. Allergies should, however, be taken seriously as in extreme cases an allergic reaction can cause anaphylactic shock and even death.

The role of the allergist

An allergist is a doctor who specialises in the diagnosis of allergic diseases. Allergists are trained to identify the factors that trigger allergies and help people treat or prevent allergies.

Before an allergy can manifest, the person firstly has to have the tendency towards an allergy and secondly be exposed to an allergen.   

The most reliable allergy tests are the skin test and blood test. The blood test measures the levels of IgE antibodies in your body after eating certain foods, while in the skin test microscopic amounts of common allergens are placed under the first layer of skin, and if you're allergic to something, you'll see a mosquito bite-like bump within 15 to 30 minutes.

Although there is much about allergies that is still not understood, an allergy usually begins with sensitisation when the person is exposed to an allergen.

Repeated exposure to this substance triggers the immune system to form the antibodies that cause the allergic reaction.

Identifiable risk factors

Allergic reactions are notoriously difficult to predict and can affect anyone, regardless of age, gender, race or socioeconomic factors. Allergies are more common in children, but can occur for the first time at any age. Allergy symptoms can for example start in childhood, disappear for many years and then start up again during adult life.

The ability to identify allergy sufferers as early as possible is without any doubt a great advantage in avoiding dangerous situations like anaphylaxis.

Allergists are aware that there are certain factors that make some people more likely to become allergy sufferers.

A previous Health24 article lists three main identifiable risk factors for developing allergies:

1. Genetics is arguably the most important factor in determining whether you will have an allergy or not (susceptibility).

2. Your environment will set the process in motion as it will determine which antigens (if any) you are exposed to.

3. Upper respiratory infections are a factor because children who contract viral or bacterial infections of the upper respiratory system before the age of six months are more likely to develop allergies or conditions such as asthma later in life.

Parents under the spotlight

If both parents have allergies, their children are more likely to develop an allergy, although not always the same kind of allergy.

If one parent has an allergy, a child has a 30 to 50% risk of inheriting the tendency to be allergic (atopic), although the specific allergy or allergies may different. This means that if you’re allergic to cats and dogs, your children may be fine with pets but react violently to peanuts, eggs and kiwi fruit, for example.

If both parents suffer from allergies, their children have a 60 to 80% likelihood of developing allergies.

Other clues

A Canadian study came to the conclusion that children who have eczema at age one and who are already “sensitised” to an allergen are seven times more likely than other babies to develop asthma, and significantly more likely to develop a food allergy by age three.

These findings could help doctors better predict which children will go on to develop asthma and allergies.

In addition, the Journal of Allergy and Clinical Immunology recently pinpointed a new gene associated with peanut allergy, offering further evidence that genes play a role in the development of food allergies.

The gene is already known to play a role in other allergy-related conditions, such as eczema, asthma and allergic rhinitis. The findings of the study suggest that this gene plays an important role in the development of not just food allergy but also general allergic predisposition.

Preventing allergies

A strong genetic basis for allergies has been firmly established, and as research progresses it is possible that a way may be found to eliminate the genetic cause of all allergies.

In the meantime, however, the best way of preventing an allergic response – once the allergy has been identified – is to avoid any contact with the allergen.  

Image credit: iStock


Ask the Expert

Allergy expert

Dr Morris is the Principal Allergist at the Cape Town and Johannesburg Allergy Clinics with postgraduate diplomas in Allergology, Dermatology, Paediatrics and Family Medicine dealing with both adult and childhood allergies.

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