Allergic diseases in children, such as allergic asthma (allergy of the lungs), allergic rhinitis (allergy of the nose) and atopic dermatitis (eczema) have increased over the past 20 to 30 years. The exact cause(s) for this increase has not been identified, but it seems that a close relationship with a 'western lifestyle', resulting in a decreased bacterial load (e.g. less contacts of the human body with bacteria, leading to decreased levels of colonisation, especially of the intestine, also called "altered commensal flora") of young children, may be responsible. Apart from a decreased bacterial load, other factors have also been associated with the increased prevalence of allergic diseases. These include: indoor and outdoor pollution, vaccination programmes, viral infections (eg respiratory syncytial virus) and an increased use of medication, such as antibiotics and paracetamol.
The cause of allergy is multi-factorial, and the development of an allergic disease is the result of the complex interactions between genetic and environmental factors. Furthermore, it has now been accepted that allergic immune responses may start from birth. Different nutritional, immunologic, and environmental factors during pregnancy all play a role in determining whether or not a child will be born with the propensity to develop allergic sensitization and subsequent allergic disease.
In young children, eczema and chronic diarrhoea are the main first manifestations of allergy, which in older children allergy manifests itself more often as a chronic or recurrent respiratory disease (asthma and/or rhinitis). Furthermore, food allergy (egg, cow’s milk) is the main type of allergic reaction during the first year of life, causing eczema and intestinal problems, while allergy of inhaled allergens eg house dust mite, pets seldom occurs during infancy. In contrast food allergy in older children most commonly causes skin symptoms (hives, urticaria), and foods causing these allergic reactions are peanuts, fish, bird nest, and shellfish.
Treatment of allergic diseases involves allergen avoidance and symptomatic treatment using medications, such as corticosteroids, antihistamines and anti-asthmatic medication. A number of patients benefit from specific immunotherapy using subcutaneous sublingual administration of allergens (SLIT). More recently, the first studies with the antibody that blocks the effects of the allergic antibody, IgE gave promising results. In another study the combination of anti-IgE and specific immunotherapy was very effective in children suffering from seasonal allergic rhinitis due to a pollen allergy. However, allergic conditions still cannot be cured, hence prevention of symptoms remains the mainstay in the management of potentially allergic children.
Preventive measures of atopy constitute avoidance of early allergen contacts and avoidance of pollution. The effect of early avoidance of allergens is still a matter of debate, and currently it is still not clear whether primary avoidance of allergens has any beneficial effect or whether it may facilitate allergic sensitization.
As in every infant, breast-feeding is generally considered as the first choice for atopic infants. The extend to which it prevents allergy is still unclear. At the very least, breast-feeding appears to delay or prevent the occurrence of cow's milk allergy.
Hypo-allergenic formulas have an inhibitory effect upon the development of cow's milk allergy. Moreover, late introduction (after the age of 6 months) to solid foods appears advisable in atopic infants. Administration of eggs should be avoided in infants with atopic eczema. The effect of early administration of probiotics is promising, especially in those young children with eczema. Probiotics seem to be less effective of the prevention of asthma.
Some medications have been found to modify the development of atopic disease. In one study, early usage of ketotifen in infants suffering from eczema was able to prevent the occurrence of asthma. In another study, the same drug inhibited the occurrence of asthma in high risk, symptom-free infants.
More recently, it was found that cetirizine was able to delay or prevent the development of asthma in young children suffering from atopic eczema and allergy to house dust mites as well as grass pollen. More studies and more long term data are required to substantiate this finding.
In conclusion, we now have good and safe medications to control symptoms of allergy. However a curative treatment is still not available. At the moment, a number of studies are running on the effect of immunotherapy in the prevention of allergic studies.
This article was first published in I CAN! Newsletter July 2006 issue. Used with permission.
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