Thunderstorm-triggered asthma: what we know so far

Journal of Asthma and Allergy Dovepress open access to scientific and medical research Journal of Asthma and Allergy downloaded from https://www.dovepress.com/ by 88.198.20.149 on 28-Sep-2019 For personal use only. Open Access Full Text Article REVIEW Thunderstorm-triggered asthma: what we know so far This article was published in the following Dove Press journal: Journal of Asthma and Allergy Nur-Shirin Harun 1,2 Philippe Lachapelle 3,4 Jo Douglass 2,3 1 Department of Respiratory and Sleep Medicine, The Royal Melbourne Hospital, Melbourne, VIC, 3050, Australia; 2Lung Health Research Centre, The University of Melbourne, Melbourne, VIC, 3052, Australia; 3Department of Immunology and Allergy, The Royal Melbourne Hospital, Melbourne, VIC, 3050, Australia; 4Pulmonary Division, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, QC, Canada Abstract: Thunderstorm-triggered asthma (TA) is the occurrence of acute asthma attacks immediately following a thunderstorm. Epidemics have occurred across the world during pollen season and have the capacity to rapidly inundate a health care service, resulting in potentially catastrophic outcomes for patients. TA occurs when specific meteorological and aerobiological factors combine to affect predisposed patients. Thunderstorm outflows can concentrate aeroallergens, most commonly grass pollen in TA, at ground level to release respirable allergenic particles after rupture by osmotic shock related to humidity and rainfall. Inhalation of high concentrations of these aeroallergens by sensitized individuals can induce early asthmatic responses which are followed by a late inflammatory phase. Other environmental factors such as rapid temperature change and agricultural practices contribute to the causation of TA. The most lethal TA event occurred in Melbourne, Australia, in 2016. Studies on the affected individuals found TA to be associated with allergic rhinitis, ryegrass pollen sensitization, pre-existing asthma, poor adherence to inhaled corticosteroid preventer therapy, hospital admission for asthma in the previous year and outdoor location at the time of the storm. Patients without a prior history of asthma were also affected. These factors are important in extending our understanding of the etiology of TA and associated clinical indicators as well as possible biomarkers which may aid in predicting those at risk and thus those who should be targeted in prevention campaigns. Education on the importance of recognizing asthma symptoms, adherence to asthma treatment and controlling seasonal allergic rhinitis is vital in preventing TA. Consideration of allergen immunotherapy in selected patients may also mitigate risk of future TA. Epidemic TA events are predicted to increase in frequency and severity with climate change, and identifying susceptible patients and preventing poor outcomes is a key research and public health policy priority. Keywords: asthma, thunderstorm, rhinitis, ryegrass Introduction Correspondence: Nur-Shirin Harun Department of Respiratory and Sleep Disorders Medicine, The Royal Melbourne Hospital, Grattan St, Parkville, Melbourne, VIC, 3050, Australia Tel +6 139 342 7708 Email 101 submit your manuscript | www.dovepress.com Journal of Asthma and Allergy 2019:12 101–108 DovePress © 2019 Harun et al. This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms. php and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License (http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms (https://www.dovepress.com/terms.php). http://doi.org/10.2147/JAA.S175155 Powered by TCPDF (www.tcpdf.org) Thunderstorm-triggered asthma (TA) is the occurrence of acute asthma attacks immediately following a thunderstorm.1 TA epidemics are uncommon and are believed to occur when specific meteorological and aerobiological conditions combine to affect predisposed patients. Symptoms such as breathlessness, cough or wheeze occur suddenly in such patients due to bronchospasm and often require emergency medical treatment via a general practitioner or emergency department (ED) presentation and/or hospitalization. Episodes occur typically during storms in pollen season across the world.2 The largest and most devastating epidemic of TA occurred in Melbourne, Australia, in November 2016 where more than 3,400 people sought emergency medical attention and 10 deaths were reported.3–6 The unprecedented scale and Dovepress Journal of Asthma and Allergy downloaded from https://www.dovepress.com/ by 88.198.20.149 on 28-Sep-2019 For personal use only. Harun et al severity of the attack and the unexpected nature of the event saw emergency services rapidly overwhelmed.3,4 It demanded an urgent and thorough investigation into the phenomenon of TA via coronial inquiry and a rethink on the likely attributable factors and what we can do to prevent such tragic outcomes in the future. Since the Melbourne 2016 event, there have been a number of publications that have furthered our understanding of TA. In the absence of randomized trial data, we rely on retrospective analyses for potential risk associations as well as data from some case-control studies. Further research using larger cohorts and longer-term studies are required. Epidemiology Epidemics of TA have occurred throughout the world and are characterized by a rapid increase in emergency visits for asthma to general practices or hospital EDs following a storm, above what would normally be expected for that area.1,5 In Australia, community pharmacies can also be overwhelmed, likely due to the over-the-counter availability of short-acting β2-agonist (SABA) medications.3 These epidemics affect large numbers of people and can be potentially fatal, as the Melbourne 2016 epidemic uncovered.5 TA epidemics were first described over 30 years ago and have occurred in the UK, North America, Southern Europe and the Middle East during the late spring or early summer pollen seasons (Table 1).4,5 Most frequently however, events have occurred in Australia – all during the Spring season and most commonly in November – with at least six discrete events in Melbourne alone since 1984 and elsewhere including rural New South Wales and Canberra.3–5 Grass pollen is believed to have triggered all Australian events as well as the majority of events worldwide. Fungal spores and other types of pollen (such as olive) have been implicated in some of the events in the UK, Italy and Canada.4,7 While TA epidemics are considered relatively uncommon, asthma exacerbations following thunderstorms are likely underreported. An observa (...truncated)