Thunderstorm asthma: An allergen-induced early asthmatic response

Prediction of airborne pollen and sub-pollen particles for thunderstorm asthma outbreaks assessment

When exposed to convective thunderstorm conditions, pollen grains can rupture and release large numbers of allergenic sub-pollen particles (SPPs). These sub-pollen particles easily enter deep into human lungs, causing an asthmatic response named thunderstorm asthma (TA). Up to now, efforts to numerically predict the airborne SPP process and to forecast the occurrence of TAs are unsatisfactory. To overcome this problem, we have developed a physically-based pollen model (DREAM-POLL) with parameterized formation of airborne SPPs caused by convective atmospheric conditions. We ran the model over the Southern Australian grass fields for 2010 and 2016 pollen seasons when four largest decadal TA epidemics happened in Melbourne. One of these TA events (in November 2016) was the worldwide most extreme one which resulted to nine deaths and hundreds of hospital patient presentations. By executing the model on a day-by-day basis in a hindcast real-time mode we predicted SPP peaks exclusively only when the four major TA outbreaks happened, thus achieving a high forecasting success rate. The proposed modelling system can be easily implemented for other geographical domains and for different pollen types.

A Review of the Respiratory Health Burden Attributable to Short-Term Exposure to Pollen

Respiratory diseases such as asthma, allergic rhinitis (AR) and chronic obstructive pulmonary disease (COPD) affect millions worldwide and pose a significant global public health burden. Over the years, changes in land use and climate have increased pollen quantity, allergenicity and duration of the pollen season, thus increasing its impact on respiratory disease. Many studies have investigated the associations between short-term ambient pollen (i.e., within days or weeks of exposure) and respiratory outcomes. Here, we reviewed the current evidence on the association between short-term outdoor pollen exposure and thunderstorm asthma (TA), asthma and COPD hospital presentations, general practice (GP) consultations, self-reported respiratory symptoms, lung function changes and their potential effect modifiers. The literature suggests strong evidence of an association between ambient pollen concentrations and almost all respiratory outcomes mentioned above, especially in people with pre-existing respiratory diseases. However, the evidence on sub-clinical lung function changes, COPD, and effect modifiers other than asthma, hay fever and pollen sensitisation are still scarce and requires further exploration. Better understanding of the implications of pollen on respiratory health can aid healthcare professionals to implement appropriate management strategies.

Thunderstorms, Pollen, and Severe Asthma in a Midwestern, USA, Urban Environment, 2007-2018

BACKGROUND

Previous research has shown an association between individual thunderstorm events in the presence of high pollen, commonly called thunderstorm asthma, and acute severe asthma events, but little work has studied risk over long periods of time, using detailed measurements of storms and pollen.

METHODS

We estimated change in risk of asthma-related emergency room visits related to thunderstorm asthma events in the Minneapolis-St. Paul metropolitan area over the years 2007-2018. We defined thunderstorm asthma events as daily occurrence of two or more lightning strikes during high pollen periods interpolating weather and pollen monitor data and modeling lightning counts. We acquired daily counts of asthma-related emergency department visits from the Minnesota Hospital Association and used a quasi-Poisson time-series regression to estimate overall relative risk of emergency department visits during thunderstorm asthma events.

RESULTS

We observed a 1.047 times higher risk (95% CI:1.012,1.083) of asthma-related emergency department visits on the day of thunderstorm asthma event. Our findings are robust to adjustment for temperature, humidity, wind, precipitation, ozone, PM2.5, day of week, and seasonal variation in asthma cases. Occurrence of lightning alone or pollen alone showed no association with risk of severe asthma. A two-stage analysis combining individual zip code level results shows similar RR and we see no evidence of spatial correlation or spatial heterogeneity of effect.

DISCUSSION

Our results support an association between co-occurrence of lightning and pollen and risk of severe asthma events. Our approach incorporates lightning and pollen data and small-spatial area exposure and outcome counts.

Thunderstorm Asthma: Looking Back and Looking Forward

Epidemic thunderstorm asthma has been reported to have occurred around twenty times over the past three decades in locations around the world. Thunderstorm asthma events are characterized by a significant increase in asthma presentations, which on occasion can overwhelm local medical services and result in fatalities. This review article presents the epidemiological data underpinning previous thunderstorm asthma events and analyzes what is known about the etiology of this unusual phenomenon. The evidence behind published risk factors, both at the individual and population level, is discussed. Research from the fields of allergy, pulmonology, meteorology, and climatology is drawn together and critically reviewed to surmise future predictions regarding thunderstorm asthma episodes. Finally, evidence-based individual, community, and environmentally targeted preventive strategies are presented.

Natural history of asthma symptoms after epidemic thunderstorm asthma: a 3-year longitudinal study

Background

The world's most catastrophic epidemic thunderstorm asthma event (ETSA) affected Melbourne in 2016. Little is known about the natural history of individuals affected by such extreme events.

Objective

In this single center prospective 3-year longitudinal study, symptomatology and behaviors of individuals affected by ETSA were assessed.

Methods

Standardized telephone questionnaire was used to evaluate frequency of asthma symptoms, inhaled corticosteroid preventer use, asthma action plan ownership, and healthcare utilization. Questionnaires were administered at 12, 24, and 36 months after 2016 ETSA. Subgroup analyses of the ‘current’, ‘past’, ‘possible,’ and ‘no asthma’ subgroups were also conducted.

Results

Two hundred and eight, 164, and 112 completed questionnaires were analyzed in 2017, 2018, and 2019, respectively. Seventy to eighty five percent of respondents reported ongoing asthma symptoms in any given year, of which 20%–28% experienced weekly symptoms. Nearly 50% of respondents were prescribed preventers, with approximately 45% adherent at least 5 days a week. Less than 40% had an asthma action plan and 15%–20% sought urgent medical attention for asthma over the follow-up period. Among 106 individuals with 3 consecutive years of completed questionnaires, those with no prior doctor diagnosis of asthma were significantly more likely to be asymptomatic on follow-up than those with a prior doctor diagnosis of asthma (p = 0.02). Subgroup analyses suggest that large proportions of respondents with ‘past’ and ‘no asthma’ continue to remain symptomatic throughout the 36-month period.

Conclusion

In individuals affected by ETSA, we found evidence of ongoing loss of asthma control in those with previously well controlled asthma, and the persistence of symptoms suggestive of asthma in those with no history or symptoms suggestive of prior asthma, even after 36 months from initial ETSA. Low rates of inhaler adherence and asthma action plan ownership may contribute to increased morbidity and mortality from future ETSA events. Further research is required to confirm these findings.

Aeroallergen Exposure and Spread in the Modern Era

Since the initial discovery of aeroallergens in the 20th century, our understanding of their properties including sources and factors influencing their spread continues to expand. Both habits of daily living and the presence of environmental factors such as exposure to animals or pollution can influence susceptibility to atopic disease. Because relevant allergens may vary in individuals and communities, it is necessary to understand the physical properties of environmental aeroallergens that are associated with clinical disease to explain symptoms and to implement successful integrated interventions. The objective of this review was to present an overview of aeroallergens and the environmental factors influencing their current distribution. Using historical studies along with recent advancements, we will give an up-to-date description of the physical characteristics and aerodynamics of aeroallergens in addition to location, quantities, and timing of exposure.

Continued loss of asthma control following epidemic thunderstorm asthma

Background

Epidemic thunderstorm asthma (ETSA) severely affected Melbourne, Australia in November 2016. There is scant literature on the natural history of individuals affected by ETSA.

Objective

A multicentre 12-month prospective observational study was conducted assessing symptomatology and behaviors of ETSA-affected individuals.

Methods

We used a structured phone questionnaire to assess asthma symptom frequency, inhaled preventer use, asthma action plan ownership and healthcare utilization over 12 months since the ETSA. Analysis of results included subgroup analyses of the “current,” “past,” “probable,“ and “no asthma” subgroups defined according to their original 2016 survey responses.

Results

Four hundred forty-two questionnaires were analyzed. Eighty percent of individuals reported ongoing asthma symptoms at follow-up, of which 28% were affected by asthma symptoms at least once a week. Risk of persistent asthma symptoms was significantly higher in those with prior asthma diagnosis, current asthma, and probable undiagnosed asthma (all p < 0.01). Of 442 respondents, 53% were prescribed inhaled preventers, of which 51% were adherent at least 5 days a week. Forty-two percent had a written asthma action plan and 16% had sought urgent medical attention for asthma in the preceding year.

Conclusions

Following an episode of ETSA, patients experience a pivotal change in asthma trajectory with both loss of asthma control and persistence of de novo asthma. Suboptimal rates of inhaled preventer adherence and asthma action plan ownership may contribute to asthma exacerbation risk and susceptibility to future ETSA episodes. Longer-term follow-up is needed to determine the extent and severity of this apparent change.

Update in Pediatric Asthma: Selected Issues

Asthma is a complex condition that affects 14% of the world's children and the approach to management includes both pharmacologic as well as non-pharmacologic strategies including attention to complex socioeconomic status phenomena. After an historical consideration of asthma, allergic and immunologic aspects of asthma in children and adolescents are presented. Concepts of socioeconomic aspects of asthma are considered along with environmental features and complications of asthma disparities. Also reviewed are links of asthma with mental health disorders, sleep disturbances and other comorbidities. A stepwise approach to asthma management is discussed that includes pharmacologic and non-pharmacologic strategies in the pediatric population. The role of immunotherapy and use of various immunomodulators are considered as well.

Thunderstorm-triggered asthma: what we know so far

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.

Beta-blocker use is an independent risk factor for thunderstorm asthma

OBJECTIVE

To identify risk factors for thunderstorm asthma (TA) in subjects ≥15 years of age from information available in routine clinical records.

METHODS

Retrospective and hospital-based case-control study of various clinical factors in all TA cases (n = 53) who presented to a single-site ED in November 2016 (TA16) and in a control group of patients (n = 156) who presented to the same ED with asthma during the pollen season over eight non-TA years. Bivariate analysis and multivariable logistic regression modelling was performed to calculate the odds of TA asthma in the presence of potential risk factors.

RESULTS

A logistic regression model revealed that the odds of TA were lower for age (odds ratio [OR] 0.97, 95% confidence interval [CI] 0.95-0.99), higher for Asian country of birth (OR 4.09, 95% CI 1.40-11.95) and higher for oral beta-blocker use (OR 6.43, 95% CI 1.58-26.33) compared to controls. No difference was found between TA16 cases and controls for allergies (to medication, grass pollen, animal), hayfever, smoking, oral non-steroidal anti-inflammatory drugs, or aspirin. Newly diagnosed asthma was higher in TA16 cases versus controls (32.1% vs 12.2%, P = 0.001).

CONCLUSIONS

Oral beta-blocker medications, younger age and Asian-born heritage are risk factors for TA. Further study is required to explore the potential association between beta-blockers and TA.

Aeroallergens in Canada: Distribution, Public Health Impacts, and Opportunities for Prevention

Aeroallergens occur naturally in the environment and are widely dispersed across Canada, yet their public health implications are not well-understood. This review intends to provide a scientific and public health-oriented perspective on aeroallergens in Canada: their distribution, health impacts, and new developments including the effects of climate change and the potential role of aeroallergens in the development of allergies and asthma. The review also describes anthropogenic effects on plant distribution and diversity, and how aeroallergens interact with other environmental elements, such as air pollution and weather events. Increased understanding of the relationships between aeroallergens and health will enhance our ability to provide accurate information, improve preventive measures and provide timely treatments for affected populations.