Microgeographic factors and patterns of aeroallergen sensitisation

Abstract

Objective: To examine patterns of airborne allergen (aeroallergen) sensitisation in the Greater Sydney area (Sydney), and their relationships with climate, coastal proximity and environment (urban v regional). Design, setting, participants: Retrospective cross‐sectional study of patients who underwent aeroallergen skin prick testing at three Sydney allergy clinics, January 2001 – October 2014. Main outcome measurements: Proportions of patients sensitised to specific aeroallergen types; relationships between sensitisation patterns and climate and geography. Results: Of 1421 patients who met the selection criteria (mean age, 28.3 years [SD, 21.3]; 53.3% were female), 1092 (76.8%) were sensitised to at least one aeroallergen. Those living less than 15 km from the coast were less commonly sensitised to cockroach (< 15 km, 15.1%; 15–30 km, 40.0%; > 30 km, 39.7%; P < 0.001) and grass aeroallergens (< 15 km, 36.5%; 15–30 km, 52.2%; > 30 km, 58.1%; P < 0.001) than patients further inland; the same applied to mould, weed and tree aeroallergens. Subtropical grass sensitisation was more common in temperate/warm summer climates (about 50%) than in temperate/hot summer (27.1%) or subtropical climates (15%) (P < 0.001), and less common in urban (36.7%) than in regional areas (54%; P = 0.014). 72.4% of grass‐sensitised patients were co‐sensitised to both temperate and subtropical grasses. A selected ten‐aeroallergen skin prick test panel identified 98.5% of atopic patients in this Sydney sample. Conclusions: Environmental and geographic factors are associated with different patterns of allergic sensitisation in Sydney. Extensive co‐sensitisation to subtropical and temperate grasses has implications for immunotherapy in Australia, where most currently available therapies are based on formulations directed at temperate grasses only.

Climate change and allergy in Australia: an innovative, high-income country, at potential risk

“…5 For example, in Australia, variation in climate even within the city of Sydney is associated with differing allergy patterns, with those living less than 15 km from the coast being less commonly sensitised to grass aeroallergens than people further inland. 14 Similarly, a recent study in South East Queensland found allergy to Eucalyptus pollen was significantly more common in people located on the coast compared with those living nearby in a more inland and elevated location. 15 Recent synthesis and analysis of all available airborne pollen data for Australia has revealed just how important the role of climate is.…”

Allergen immunotherapy for respiratory allergic disease in Australia in 2016

“…Each person is sensitised to a different combination of allergens, although there are common patterns that may vary geographically. 4 Component testing, which identifies specific IgE to individual allergenic proteins or epitopes, promises to provide further information to guide the choice of allergens for immunotherapy. 15 The complexity of allergen extracts, their derivation from natural sources, and the large and diverse range of allergens do not fit well into the pharmaceutical product regulatory framework.…”

“…“Epidemics” of severe and even fatal asthma after springtime thunderstorms, as seen in Melbourne in November 2016 (http://www.abc.net.au/news/2016-11-29/thunderstorm-asthma-eighth-person-dies-from-melbourne/8074776), are triggered by allergenic pollen microparticles, which (unlike intact pollen grains) penetrate into the lower airways. It is therefore important to understand the patterns of allergic sensitisation and allergen exposure of patients, which can vary geographically as recently demonstrated 4 . This understanding informs advice regarding allergen avoidance strategies (where possible), the introduction of controlling medications to counteract allergen exposure, and the use and selection of allergen immunotherapy.…”

“…Pollens also comprise many allergenic proteins, some of which are cross‐reactive between species, while others are unique. Each person is sensitised to a different combination of allergens, although there are common patterns that may vary geographically 4 . Component testing, which identifies specific IgE to individual allergenic proteins or epitopes, promises to provide further information to guide the choice of allergens for immunotherapy 15 …”

“…It is therefore important to understand the patterns of allergic sensitisation and allergen exposure of patients, which can vary geographically as recently demonstrated. 4 This understanding informs advice regarding allergen avoidance strategies (where possible), the introduction of controlling medications to counteract allergen exposure, and the use and selection of allergen immunotherapy.…”