Page - 54 - in Biodiversity and Health in the Face of Climate Change

54 products (i.e. soy drinks) have been promoted as healthy foods and are being con- sumed in increasing amounts in many European countries (Treudler et  al. 2017). Different allergen families, which are also present in plant tissues, can become airborne, as well as be found in foods, and they are associated with different types of clinical reactions (i.e. sensitisation to pathogenesis-related (PR) protein-10, like Bet v 1 homologues). These reactions are mostly seen in Northern Europe and they are associated with oral itching and swelling. In contrast, sensitisation to lipid trans- fer proteins (LTPs) occurs more frequently in Southern Europe and is associated with anaphylaxis (severe immediate-type reactions involving several organ systems). 3.3 Allergenic Pollen and  Epidemiology There are differences within pollen-producing plants with regard to their ability to induce allergic sensitisation. There have been numerous studies worldwide over the past several decades that have documented such sensitisation rates. Nonetheless, a huge variability may exist, because of (but not limited to) climatic, air quality, envi- ronmental, social and genetic differences. A short overview is provided in Table  3.1, which gives the sensitisation rates of the most important allergenic pollen types. The international literature documents grass pollen as the leading aeroallergen worldwide (e.g. Lewis et  al. 1983; Weeke and Spieksma 1991; Wu et  al. 1999; García-Mozo 2017). The reason for this is the wide distribution of grass species, along with their pollen’s high allergenicity. The grass (Poaceae) family comprises one of the largest and most common plant families worldwide and, noticeably, con- sists mostly of wind-pollinated species (e.g. Wodehouse 1971; Lewis et  al. 1983). It includes both annual and perennial herbaceous species, many of which are highly cosmopolitan and, hence, they are found in a wide variety of latitudes and biogeo- graphical zones, in both urban or natural habitats (e.g. Pignatti 1982; Lewis et  al. 1983). The grass species most implicated in respiratory allergies are orchard grass (Dactylis glomerata), fescue grass (Festuca spp.), ryegrass (Lolium perenne), timo- thy grass (Phleum pratense) and bluegrass (Poa spp.) (e.g. Lewis et  al. 1983). Sensitisation rates to grass pollen can exceed 80% of the atopic population accord- ing to many epidemiological and clinical studies carried out across the globe (Table  3.1). Other allergologically important plants are birch (Betula spp.), alder (Alnus spp.), hazel (Corylus spp.) and  – recently of growing interest  – the invasive ragweed (Ambrosia spp.). Sensitisation rates for the above pollen types can exceed 50% for the Corylaceae and Betulaceae families, whereas sensitisation to ragweed pollen can reach up to 80% (Table  3.1). However, if investigating the exact relationship of the actual pollen exposure to the respiratory allergic symptoms of sensitised individuals, there are specific pre- requisites. The exact pollen season occurrence and intensity need to be defined on a spatial and a temporal scale. Pollen allergy symptoms are mostly observed during A. Damialis et  al.