title: Rhinoviruses significantly affect day-to-day respiratory symptoms of children with asthma.
abstract: BACKGROUND
  Viruses are frequently associated with acute exacerbations of asthma, but the extent to which they contribute to the level of day-to-day symptom control is less clear.
  
  
  OBJECTIVE
  We sought to explore the relationship between viral infections, host and environmental factors, and respiratory symptoms in children.
  
  
  METHODS
  Sixty-seven asthmatic children collected samples twice weekly for an average of 10 weeks. These included nasal wash fluid and exhaled breath for PCR-based detection of viral RNA, lung function measurements, and records of medication use and asthma and respiratory symptoms in the previous 3 days. Atopy, mite allergen exposure, and vitamin D levels were also measured. Mixed-model regression analyses were performed.
  
  
  RESULTS
  Human rhinoviruses (hRVs) were detected in 25.5% of 1232 nasal samples and 11.5% of breath samples. Non-hRV viruses were detected in less than 3% of samples. hRV in nasal samples was associated with asthma symptoms (cough and phlegm: odds ratio = 2.0; 95% CI = 1.4-2.86, P = .0001; wheeze and chest tightness: odds ratio = 2.34, 95% CI = 1.55-3.52, P < .0001) and with cold symptoms, as reported concurrently with sampling and 3 to 4 days later. No differences were found between the 3 hRV genotypes (hRV-A, hRV-B, and hRV-C) in symptom risk. A history of inhaled corticosteroid use, but not atopic status, mite allergen exposure, or vitamin D levels, modified the association between viruses and asthma symptoms.
  
  
  CONCLUSIONS
  The detection of nasal hRV was associated with a significantly increased risk of day-to-day asthma symptoms in children. Host, virus genotype, and environmental factors each had only a small or no effect on the relationship of viral infections to asthma symptoms.
authors.affiliation: Woolcock Institute of Medical Research, University of Sydney, Sydney, Australia. Electronic address: euan.tovey@sydney.edu.au.
authors.forename: Euan R
authors.initials: ER
authors.lastname: Tovey
authors.affiliation: Virology Research Laboratory, SEALS, Prince of Wales Hospital, Sydney, Australia; School of Medical Sciences, University of New South Wales, Sydney, Australia.
authors.forename: Sacha
authors.initials: S
authors.lastname: Stelzer-Braid
authors.affiliation: Woolcock Institute of Medical Research, University of Sydney, Sydney, Australia; Sydney Local Health District, Sydney, Australia.
authors.forename: Brett G
authors.initials: BG
authors.lastname: Toelle
authors.affiliation: Woolcock Institute of Medical Research, University of Sydney, Sydney, Australia; University of Technology Sydney, Sydney, Australia.
authors.forename: Brian G
authors.initials: BG
authors.lastname: Oliver
authors.affiliation: Woolcock Institute of Medical Research, University of Sydney, Sydney, Australia.
authors.forename: Helen K
authors.initials: HK
authors.lastname: Reddel
authors.affiliation: Virology Research Laboratory, SEALS, Prince of Wales Hospital, Sydney, Australia.
authors.forename: Christiana M
authors.initials: CM
authors.lastname: Willenborg
authors.affiliation: School of Women's and Children's Health, University of New South Wales, Sydney, Australia; Sydney Children's Hospital, Sydney, Australia.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Belessis
authors.affiliation: Woolcock Institute of Medical Research, University of Sydney, Sydney, Australia; Ingham Institute of Applied Medical Research, New South Wales, Sydney, Australia; South Western Sydney Clinical School, University of New South Wales, Sydney, Australia.
authors.forename: Frances L
authors.initials: FL
authors.lastname: Garden
authors.affiliation: School of Women's and Children's Health, University of New South Wales, Sydney, Australia; Sydney Children's Hospital, Sydney, Australia.
authors.forename: Adam
authors.initials: A
authors.lastname: Jaffe
authors.affiliation: Sydney Children's Hospital, Sydney, Australia.
authors.forename: Roxanne
authors.initials: R
authors.lastname: Strachan
authors.affiliation: Queensland Brain Institute, University of Queensland, Brisbane, Australia; Queensland Centre for Mental Health Research, The Park Centre for Mental Health, Brisbane, Australia.
authors.forename: Darryl
authors.initials: D
authors.lastname: Eyles
authors.affiliation: Virology Research Laboratory, SEALS, Prince of Wales Hospital, Sydney, Australia; Sydney Children's Hospital, Sydney, Australia.
authors.forename: William D
authors.initials: WD
authors.lastname: Rawlinson
authors.affiliation: Woolcock Institute of Medical Research, University of Sydney, Sydney, Australia; South Western Sydney Clinical School, University of New South Wales, Sydney, Australia.
authors.forename: Guy B
authors.initials: GB
authors.lastname: Marks
mesh_terms: D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use; D039741:Antigens, Dermatophagoides / Q000097:blood / Q000276:immunology; D001249:Asthma / Q000150:complications* / Q000188:drug therapy / Q000276:immunology / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D003371:Cough / Q000503:physiopathology; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D010850:Picornaviridae Infections / Q000150:complications* / Q000188:drug therapy / Q000276:immunology / Q000503:physiopathology; D012044:Regression Analysis; D012129:Respiratory Function Tests; D012135:Respiratory Sounds / Q000503:physiopathology; D012229:Rhinovirus / Q000235:genetics / Q000276:immunology*; D014807:Vitamin D / Q000097:blood / Q000276:immunology
chemical_list: D000305:Adrenal Cortex Hormones; D018927:Anti-Asthmatic Agents; D039741:Antigens, Dermatophagoides; D014807:Vitamin D
keywords: Virus; asthma; asthma control; children; mixed-model analysis; respiratory; rhinovirus