Associations between outdoor fungal spores and childhood and adolescent asthma hospitalisations

Rachel Tham, Don Vicendese, Shyamali C Dharmage, Rob J Hyndman, Ed Newbigin, Emma Lewis, Molly O'Sullivan, Adrian J Lowe, Philip Taylor, Philip Bardin, Mimi L Tang, Michael J Abramson, Bircan Erbas.
(2017) Journal of Allergy and Clinical Immunology, 139(4), 1140–1147.e4

DOI

Background: Childhood asthma is a significant public health problem and severe exacerbation can result in diminished quality of life and hospitalisation.

Objective: To examine the contribution of outdoor fungi to childhood and adolescent asthma hospitalisations

Methods: The Melbourne Air Pollen Children and Adolescent (MAPCAH) study is a case-crossover study of 644 children and adolescents (aged 2-17 years) hospitalised for asthma between September 2009 and December 2011. MAPCAH collected individual data on human rhinovirus (HRV) infection and fungal sensitisation; and daily counts of ambient concentrations of fungal spores, pollen and air pollutants. Conditional logistic regression models were used to assess associations between interquartile increases in spore counts and controlling for potential confounding and interactions.

Results: Exposure to Alternaria (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%CI1.00-1.05) and total spores (aOR=1.05, 95%CI 1.01-1.09) were significantly associated with child asthma hospitalisations independent of HRV 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 sensitisation.

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