Page - 49 - in Biodiversity and Health in the Face of Climate Change

49 3.2 Clinical Implications of  Pollen-induced Respiratory Allergy Allergies represent a major public health problem, one that has increased rapidly in recent decades in both developed and developing countries and one that is recog- nised as an important global epidemic carrying a considerable economic burden (Bieber et  al. 2016; Linneberg 2016; Traidl-Hoffmann 2017). For the clinical manifestation of allergic symptoms, there is a need for allergic sensitisation to pollen allergens resulting in IgE antibody production. IgE antibod- ies bind to an IgE-specific receptor on the surface of immune cells (mast cells and basophils), and if later exposure to the same allergen occurs, the allergen can bind to the IgE molecules on the surface of these cells, thereby activating them. Activated mast cells and basophils undergo degranulation, during which they release hista- mine and other inflammatory chemical mediators into the surrounding tissue, caus- ing vasodilation, mucous secretion, nerve stimulation and smooth muscle contraction (Averbeck et  al. 2007). In pollen allergies, the most common symptoms induced by allergens are sneez- ing, itchy nose, rhinorrhea and nasal congestion (Averbeck et  al. 2007). Inhaled allergens can also result in exacerbation of bronchial allergic asthma, with cough- ing, wheezing, shortness of breath, chest tightness, pain or pressure. In industrialised countries, allergic rhinitis (AR) can affect more than 20% of the population, as has been reviewed by Linneberg (2011). This percentage varies among cities, countries and continents because of environmental and other factors, and can exceed 40% (e.g. Brożek et  al. 2017; Morais-Almeida et  al. 2013; Sibbald and Strachen 1995). For example, the lifetime prevalence of allergic diseases in adults in Germany is 8.6% (95% CI) for asthma and 14.8% (95% CI) for rhinitis, as measured by self-reported doctor-diagnosed allergies within the Study on Adult Health in Germany of the Robert Koch Institute for rhinitis (Bergmann et  al. 2016; Langen et  al. 2013; Haftenberger et  al. 2013). Regarding allergic sensitisation, in tests on 50 common single allergens and two mixtures comprising either inhalant allergens or grass pollen allergens, 48.6% of participants exhibited at least one aller- gic sensitisation (specific IgE antibody detection). Overall, 33.6% of participants were sensitised to inhalant allergens (Haftenberger et  al. 2013). Table  3.1 shows sensitisation rates to 17 different pollens in atopic patients  across the globe: the vari- ous pollen types refer to the most widespread and allergenic ones worldwide, and the spatial variability and relative occurrence can be concluded based on the differ- ent cohorts studied all over the world. A comparison of data on adults from 1998 (Federal Health Survey/Bundes- Gesundheitssurvey 1998, [BGS98] of the Robert Koch Institute) and 2008–2011 (DEGS1) documented an increase in the rate of sensitisation to inhalant allergens, from 29.8% to 33.6% (Haftenberger et  al. 2013). The Germany-wide lifetime preva- lence of allergic diseases in children and adolescents (Study on the Health of Children and Adolescents in Germany/Studie zur Gesundheit von Kindern und 3 Climate Change and  Pollen Allergies