title: Indoor fungal diversity and asthma: a meta-analysis and systematic review of risk factors.
abstract: BACKGROUND
  Indoor dampness increases the risk of indoor fungal growth. A complex interaction between occupant behaviors and the built environment are thought to affect indoor fungal concentrations and species diversity, which are believed to increase the risk of having asthma, exacerbation of asthma symptoms, or both. To date, no systematic review has investigated this relationship.
  
  
  OBJECTIVE
  This review aims to assess the relationship between exposure to indoor fungi identified to the genera or species level on asthma outcomes in children and adults.
  
  
  METHODS
  Ten databases were systematically searched on April 18, 2013, and limited to articles published since 1990. Reference lists were independently screened by 2 reviewers, and authors were contacted to identify relevant articles. Data were extracted from included studies meeting our eligibility criteria by 2 reviewers and quality assessed by using the Newcastle-Ottawa scale designed for assessment of case-control and cohort studies.
  
  
  RESULTS
  Cladosporium, Alternaria, Aspergillus, and Penicillium species were found to be present in higher concentrations in homes of asthmatic participants. Exposure to Penicillium, Aspergillus, and Cladosporium species were found to be associated with increased risk of reporting asthma symptoms by a limited number of studies. The presence of Cladosporium, Alternaria, Aspergillus, and Penicillium species increased the exacerbation of current asthma symptoms by 36% to 48% compared with those exposed to lower concentrations of these fungi, as shown by using random-effect estimates. Studies were of medium quality and showed medium-high heterogeneity, but evidence concerning the specific role of fungal species was limited.
  
  
  CONCLUSIONS
  Longitudinal studies assessing increased exposure to indoor fungi before the development of asthma symptoms suggests that Penicillium, Aspergillus, and Cladosporium species pose a respiratory health risk in susceptible populations. Increased exacerbation of current asthma symptoms in children and adults were associated with increased levels of Penicillium, Aspergillus, Cladosporium, and Alternaria species, although further work should consider the role of fungal diversity and increased exposure to other fungal species.
authors.affiliation: European Centre for Environment and Human Health, University of Exeter Medical School, Truro, United Kingdom.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Sharpe
authors.affiliation: European Centre for Environment and Human Health, University of Exeter Medical School, Truro, United Kingdom; Department of Geography and Planning, University of Liverpool, Liverpool, United Kingdom.
authors.forename: Nick
authors.initials: N
authors.lastname: Bearman
authors.affiliation: Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Thornton
authors.affiliation: European Centre for Environment and Human Health, University of Exeter Medical School, Truro, United Kingdom.
authors.forename: Kerryn
authors.initials: K
authors.lastname: Husk
authors.affiliation: European Centre for Environment and Human Health, University of Exeter Medical School, Truro, United Kingdom; Department of Paediatrics, University of Melbourne, Melbourne, Australia. Electronic address: n.j.osborne@exeter.ac.uk.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Osborne
mesh_terms: D000393:Air Pollutants / Q000145:classification* / Q000302:isolation & purification; D016902:Air Pollution, Indoor / Q000009:adverse effects* / Q000032:analysis; D001249:Asthma / Q000453:epidemiology*; D004781:Environmental Exposure / Q000009:adverse effects* / Q000032:analysis; D005658:Fungi / Q000145:classification* / Q000302:isolation & purification; D006801:Humans; D012307:Risk Factors
chemical_list: D000393:Air Pollutants
keywords: Systematic review; damp; indoor fungi and allergic asthma