Asthma and lower airway disease
Associations between outdoor fungal spores and childhood and adolescent asthma hospitalizations

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Background

Childhood asthma is a significant public health problem and severe exacerbations can result in diminished quality of life and hospitalization.

Objective

We sought to examine the contribution of outdoor fungi to childhood and adolescent asthma hospitalizations.

Methods

The Melbourne Air Pollen Children and Adolescent study is a case-crossover study of 644 children and adolescents (aged 2-17 years) hospitalized for asthma. The Melbourne Air Pollen Children and Adolescent study collected individual data on human rhinovirus infection and sensitization to Alternaria and Cladosporium and daily counts of ambient concentrations of fungal spores, pollen, and air pollutants. Conditional logistic regression models were used to assess associations with increases in spore counts while controlling for potential confounding and testing interactions.

Results

Exposure to Alternaria (adjusted odds ratio [aOR], 1.07; 95% CI, 1.03-1.11), Leptosphaeria (aOR, 1.05; 95% CI, 1.02-1.07), Coprinus (aOR, 1.04; 95% CI, 1.01-1.07), Drechslera (aOR, 1.03; 95% CI, 1.00-1.05), and total spores (aOR, 1.05; 95% CI, 1.01-1.09) was significantly associated with child asthma hospitalizations independent of human rhinovirus infection. There were significant lagged effects up to 3 days with Alternaria, Leptosphaeria, Cladosporium, Sporormiella, Coprinus, and Drechslera. Some of these associations were significantly greater in participants with Cladosporium sensitization.

Conclusions

Exposures to several outdoor fungal spore taxa, including some not reported in previous research, are associated with the risk of child and adolescent asthma hospitalization, particularly in individuals sensitized to Cladosporium. We need further studies to examine cross-reactivity causing asthma exacerbations. Identifying sensitization to multiple fungal allergens in children with asthma could support the design and implementation of more effective strategies to prevent asthma exacerbations.

Section snippets

Study design and population

The Melbourne Air Pollen Children and Adolescent Health (MAPCAH) study is a case-crossover study of 644 children and adolescents (aged 2-17 years) with “incident” asthma admitted to the Royal Children's Hospital in Melbourne, Australia, between September 2009 and December 2011. This study used a bidirectional time-stratified case-crossover design that has been shown to be well suited for studying the effects of transient short-term exposures (fungi spore release, air pollution changes) on the

MAPCAH participants' characteristics

The participants recruited (n = 644) were predominantly boys (63.2%); the median age of all participants was 5.2 years (range, 2-17 years), with 90% younger than 10 years. Most (69.6%) participants had HRV infection detected at admission. Skin prick tests for fungal sensitization were obtained for 630 participants, and it was found that 8.9% were sensitized to Alternaria only, 6.5% to Cladosporium only, and 13.7% to Alternaria and Cladosporium (Table I).

Fungal spore distribution

The most prevalent fungi taxa detected

Discussion

Using a case-crossover approach, we found that exposures to spores of several outdoor fungal taxa, including some that, individually, have not been reported in previous research, were associated with the risk of asthma exacerbations in children and adolescents. Alternaria, Leptosphaeria, Coprinus, and Drechslera spores were associated with asthma hospitalizations on the day of exposure. In addition, there were associations with Alternaria, Coprinus, Drechslera, and Stemphylium 1 day after

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  • Cited by (0)

    The Melbourne Air Pollen Children and Adolescent Health study was funded by the National Health and Medical Research Council (NHMRC) Project ID: 541934, but the NHMRC had no part in the study design, collection, analysis, or interpretation of the data, the writing of this manuscript, or the decision to submit it for publication. R.T. is funded by an NHMRC PhD Postgraduate Scholarship and a Centre for Air quality & health Research and evaluation (NHMRC Centre of Research Excellence) top-up scholarship. S.C.D. and A.J.L. are funded by the NHMRC.

    Disclosure of potential conflict of interest: R. Tham has received grants from the National Health and Medical Research Council (NHMRC) and the Center for Air quality & health Research and evaluation. S. C. Dharmage, A. J. Lowe, P. Bardin, M. L. K. Tang, M. J. Abramson, and B. Erbas have received grants from the NHMRC. E. Newbigin has received grants from the NHMRC and the Allergy Immunology Foundation of Australasia, has consultant arrangements with Ryco filters, and has received money from Stallergenes to support the Melbourne pollen count. M. J. Abramson holds investigator-initiated grants from Pfizer and Boehringer-Ingelheim for unrelated research, has undertaken an unrelated consultancy for AstraZeneca, and has received assistance with conference attendance from Boehringer-Ingelheim and Sanofi. The rest of the authors declare that they have no relevant conflicts of interest.

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