title: Bioaerosol production by patients with tuberculosis during normal tidal breathing: implications for transmission risk.
abstract: The size and concentration of exhaled bioaerosols may influence TB transmission risk. This study piloted bioaerosol measurement in patients with TB and assessed variability in bioaerosol production during normal tidal breathing. Understanding this may provide a tool for assessing heterogeneity in infectivity and may inform mathematical models of TB control practices and policies.
  
  
  
  Optical particle counter technology was used to measure aerosol size and concentration in exhaled air (range 0.3-20 µm in diameter) during 15 tidal breaths across four groups over time: healthy/uninfected, healthy/Mycobacterium tuberculosis-infected, patients with extrathoracic TB and patients with intrathoracic TB. High-particle production was defined as any 1-5 µm sized bioaerosol count above the median count among all participants (median count=2 counts/L).
  
  
  
  Data from 188 participants were obtained pretreatment (baseline). Bioaerosol production varied considerably between individuals. Multivariable analysis showed intrathoracic TB was associated with a 3½-fold increase in odds of high production of 1-5 µm bioaerosols (adjusted OR: 3.5; 95% CI 1.6 to 7.8; p=0.002) compared with healthy/uninfected individuals.
  
  
  
  We provide the first evidence that intrathoracic TB increases bioaerosol production in a particle size range that could plausibly transport M. tuberculosis. There is substantial variation in production within patients with TB that may conceivably relate to the degree of infectivity. Further data is needed to determine if high bioaerosol production during tidal breathing is associated with infectiousness.
authors.affiliation: Department of Infectious Disease Informatics, UCL Institute of Health Informatics, University College London, London, UK.
authors.forename: Fatima B
authors.initials: FB
authors.lastname: Wurie
authors.affiliation: Department of Clinical Research, Faculty of Infectious and Tropical Diseases, Department of Clinical Research, London School of Hygiene & Tropical Medicine, London, UK Desmond Tutu HIV Centre, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Lawn
authors.affiliation: Department of Thoracic Medicine, University College London Hospitals NHS Foundation Trust, London, UK.
authors.forename: Helen
authors.initials: H
authors.lastname: Booth
authors.affiliation: Research Department of Infection and Population Health, University College London, London, UK.
authors.forename: Pam
authors.initials: P
authors.lastname: Sonnenberg
authors.affiliation: Department of Infectious Disease Informatics, UCL Institute of Health Informatics, University College London, London, UK.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Hayward
mesh_terms: D000328:Adult; D000336:Aerosols; D045853:Exhalation; D005260:Female; D006801:Humans; D008297:Male; D008962:Models, Theoretical; D010316:Particle Size; D012306:Risk; D014376:Tuberculosis / Q000382:microbiology* / Q000635:transmission*
chemical_list: D000336:Aerosols
keywords: Infection Control; Respiratory Infection; Tuberculosis