Introduction
Allergies in children are becoming increasingly common. About every fifth child has an allergy and the tendency is rising. The most common childhood allergies are to pollen, dust mites, animal hair and certain foods.
Definition
In an allergy, the body reacts excessively to a certain substance – the allergen. Since the allergen is actually a substance that is harmless to the body, the excessive immune response is not adequate. Once the immune system has reacted excessively to an allergen, it “remembers” this reaction each time it comes into contact with the allergen and automatically triggers it.
In order for an allergic reaction to occur, a so-called sensitization must have taken place beforehand. During this sensitisation, the body comes into contact with the allergen for the first time, recognises it as harmful and reacts with an excessive immune response. This leads to the formation of allergy-specific antibodies that bind to certain cells.
During sensitization, an allergic reaction does not yet occur, but only on the second contact with the allergen. At the second contact the allergen can then bind to the cell-bound antibodies. The cells then release various substances that cause the symptoms of an allergy.
Causes
A genetic component plays a role in the development of allergies. If one parent or even both parents have one or more allergies, the risk that the child will also develop allergies is significantly increased. If only one parent is affected, the risk for the child is 30%.
If both parents have allergies, the risk is correspondingly higher, at 80%. Research has shown that children more often develop allergies that occur late or have little contact with other children or nature. Through contact with germs and pathogens, the immune system learns to fend them off.
Too much hygiene is therefore not necessarily beneficial to the development of the child. Statistically speaking, “city children” suffer from allergies more often than children in the countryside. Protective factors are therefore, for example, attendance at the crèche or kindergarten or the presence of siblings.
Dealing with animals is also protective. Breastfeeding and vaccinating children also protects against allergies. A risk factor for the development of an allergy, however, is passive smoking. So parents should definitely avoid smoking in the vicinity of their children.
Diagnosis
If the symptoms (see: Symptoms of an allergy) and the nature of the occurrence suggest that a child has an allergic disease, various examinations can be carried out. These can often be carried out by a paediatrician, alternatively by dermatologists or special allergologists. Allergy tests are usually carried out on children from the age of three years, because the immune system of infants and toddlers is not yet sufficiently mature to react correctly to the tests.
Typically, the so-called prick test is used. The children should not be too small for this test, as the test can be unpleasant and the children have to sit still for half an hour. For the test, small skin punctures are made on the flexion side of the forearm using a wooden lancet, which are perceived as small pricks.
Various substances are applied to these punctures, which can trigger an allergy. If an allergy is present, a local skin reaction with redness and wheals should occur within a few minutes. The strength of the skin reaction can roughly indicate the strength of the underlying allergy.
With the prick test, allergies of the immediate type (type I allergy) can be identified. Especially contact allergies do not lead to an allergic reaction within minutes. Here, the symptoms develop over several hours to days.
One speaks of a type IV reaction, an allergy of the delayed type/late type. In this case an epicutaneous test can be performed as a supplement. For this, allergens are applied to the back and covered with a special plaster.
After 24 to 48 hours, a medical check for a possible allergic skin reaction is performed. In addition to the two common allergy tests, a blood test can also be used to detect antibodies that develop in the course of an allergic reaction (immunoglobulin E). If this test is positive, the cause is most likely an allergy for the existing symptoms. Provocation tests with the probable triggering allergen, in the sense of exposing the child to it, such as food, are generally not carried out in children because of the possible side effects.
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