Rachel Tham, Shyamali Dharmage, Philip Taylor, Ed Newbigin, Mimi L.K. Tang, Don Vicendese, Rob J. Hyndman, Michael J. Abramson and Bircan Erbas
Asthma can be exacerbated by exposure to various fungal spores and Human Rhinovirus [HRV], but current understanding of the importance of fungal exposure to child asthma hospitalisations is limited. Moreover the interaction between HRV and fungal spore exposure on admission has not been examined.
To investigate the role of outdoor fungal spores in child asthma hospitalisations and if HRV modifies any such effect.
We conducted a case-crossover study of 644 child asthma hospitalisations in Melbourne, Australia (2009–11). On admission, participants had nasal and throat swabs that were tested using a sensitive nested multiplex PCR for HRV infection. Daily ambient spore counts of 14 fungi species were obtained using a Burkard Volumetric spore trap. Conditional logistic regression assessed the role of fungi adjusting for confounders. Interaction terms were included if there was evidence of effect modification from HRV. Results are presented as odds ratios [OR] per unit increase in daily number of fungi spores/m3 of air sampled.
Overall, higher risk of hospitalisation was observed when participants were exposed toAlternaria (OR=1.011, 95%CI 1.004-1.017), Coprinus (1.009, 1.000-1.017), Leptosphaeria(1.001, 1.000-1.013) independent of air pollution, HRV and sensitization to common allergens. There was evidence of effect modification by HRV in boys exposed toLeptosphaeria (1.028, 1.006-1.050) and Ganoderma (1.320, 1.048-1.660). No evidence of HRV effect modification in girls.
Some fungal genera are associated with increased risk of asthma hospitalisation in both sexes but the risk increased with two specific fungal genera in boys infected with HRV.