Atopic eczema. What has caused the epidemic in industrialised countries and can early intervention modify the natural history of atopic eczema?

Abstract

Atopic eczema (AE) has a lifetime prevalence of between 15 and 20% in industrialized countries, but a very low prevalence in rural Africa. The 'atopic eczema epidemic' has developed in industrialized countries within the last four decades. The disease has a strong genetic influence, so environmental factors must be responsible for the dramatic increase in disease prevalence. It is therefore fair to consider what interventions may change its prevalence. In this article, several factors are considered: the increased number of doctors in industrialized countries, the development of drugs like topical steroids and emollients, the 'demanding parents' and 'old mother' syndromes, introduction of vaccination programmes, allergen exposure, breastfeeding and the possible beneficial effects of probiotics. In 90% of children with AE, onset is before the age of 5. Its course runs over years. Approximately two out of three outgrow the disease between 7 and 12 years of age. Although its cause is unknown, type I allergic reactions are common and allergen avoidance has been attempted in many studies as a preventive measure in atopic dermatitis. However, results are rather disappointing. The use of probiotics, i.e. daily intake of Lactobacillus, has proven effective in preventing, or at least delaying, the development of atopic eczema. So has breastfeeding, although some studies cannot confirm its beneficial effect. Therapeutic interventions using antihistamines, desensitisation and control of skin inflammation using topical steroids have not proven successful in shortening the course of atopic eczema, although controlled studies are lacking. The use of emollients has, however, a documented effect in up to one of three children with mild atopic eczema. It will be interesting to observe if the new topical immuno-modulators, tacrolimus and pimecrolimus, may be able to shorten the natural course of the disease.