Epidemiology of Allergic Diseases

Allergy is not a disease itself, but a mechanism leading to disease. In clinical practice, allergy manifests in form of various different conditions such as anaphylaxis, urticaria, angioedema, allergic rhinoconjunctivitis, asthma, atopic dermatitis, as well as the colorful spectrum of food- or drug-induced hypersensitivity reactions. Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. Novel allergens are constantly being described and new allergen sources. In recent decades, the incidence of allergic diseases has continued to increase, affecting 20% of the worldwide population, especially children. Atopic diseases are becoming an epidemic and pandemic issue. Projections suggest that the global population is likely to reach 9–10 billion people by 2050, with 2–4 billion suffering from them. Studies have suggested that allergic diseases occur following a time-based order: from atopic dermatitis (AD) and food allergy in infancy to gradual development into allergic asthma (AA) and allergic rhinitis (AR) in childhood, even if some epidemiologic evidence outlines the existence of different allergic march trajectories. In recent decades, climate change has affected key aspects of human health, including allergic and respiratory diseases. The research programs contributed to the important concept of personalized medicine in many allergic diseases, and specific therapies were chosen based on specific clinical characteristics. We are witnessing important revolutions both in the diagnosis of allergic pathologies (component-resolved diagnosis, telemedicine, use of devices such as smartphones and tablet computers to support and improve health-related services) and in therapy, such as the use of biologics for many allergic pathologies, evolving toward personalized medicine.