LAUSR

Introduction/Aim: Thunderstorm Asthma is an infrequent global phenomenon which recently struck Melbourne, Australia, leading to 9 deaths and many airways-related hospital presentations. We aimed to identify characteristics of persons symptomatic during the event and not previously known to be at risk. Methods: Eastern Health is a large health network in Victoria, Australia. An anonymous electronic survey was conducted among its staff and volunteers. Results: 515 participants (80% female, n=411) completed the survey. 41% (n=211) had symptoms. 12 sought medical attention. 88% (n=267) of the asymptomatic group were white compared with 71% (n=149) of symptomatic respondents. In symptomatic respondents, a previous asthma diagnosis was reported in 38% (n=81) and a history of hayfever in 73% (n=155). Interestingly, in those without symptoms, 28% (n=85) had previously diagnosed asthma and 35% (n=107) had a hayfever history. In the group of 130 with no history of asthma but who were symptomatic during the event, 69% (n=90) reported previous typical asthma symptom (s). In comparison, 52% (n=106) of the 219 respondents with no past history of asthma and NO event symptoms reported having experienced previous typical asthma symptom(s). In those who reported windborne allergy, 64% experienced symptoms, compared with 37% of those without it. Over 25% had at least one lower respiratory tract symptom. Conclusion: Our study provides evidence for a silent large cohort who developed symptoms during the 2016 Melbourne Thunderstorm Asthma event. Although past diagnosis of asthma or asthma symptoms, non-white background, and airborne allergy history were more likely in those with symptoms, a large undiagnosed susceptible population exists.