title: Longitudinal study of influenza molecular viral shedding in Hutterite communities.
abstract: BACKGROUND
  The nature of influenza viral shedding during naturally acquired infection is not well understood.
  
  
  METHODS
  A cohort study was conducted in Hutterite colonies in Alberta, Canada. Flocked nasal swabs were collected during 3 influenza seasons (2007-2008 to 2009-2010) from both symptomatic and asymptomatic individuals infected with influenza. Samples were tested by real-time reverse-transcription polymerase chain reaction for influenza A and influenza B, and the viral load (VL) was determined for influenza A positive samples.
  
  
  RESULTS
  Eight hundred thirty-nine participants were included in the cohort; 25% (208) tested positive for influenza viruses. They experienced 238 episodes of viral shedding, of which 23 (10%) were not accompanied by symptoms. For seasonal and pandemic H1N1, VL peaked at or before onset of acute respiratory infection. For H3N2, VL peaked 2 days after the onset of acute respiratory infection, which corresponded to peaks in systemic and respiratory symptom scores. Although the duration of shedding was shorter for asymptomatic participants, the peak level of VL shedding was similar to that of symptomatic participants. Viral loads for children and adults revealed similar patterns.
  
  
  CONCLUSIONS
  Molecular viral shedding values follow symptom scores, but timing of peak VL varies by subtype. Asymptomatic infections are infrequent.
authors: Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada. loebm@mcmaster.ca
authors: Mark
authors: M
authors: Loeb
authors: Paramjit K
authors: PK
authors: Singh
authors: Julie
authors: J
authors: Fox
authors: Margaret L
authors: ML
authors: Russell
authors: Kanti
authors: K
authors: Pabbaraju
authors: Danielle
authors: D
authors: Zarra
authors: Sallene
authors: S
authors: Wong
authors: Binod
authors: B
authors: Neupane
authors: Pardeep
authors: P
authors: Singh
authors: Richard
authors: R
authors: Webby
authors: Kevin
authors: K
authors: Fonseca
mesh_terms: D000293:Adolescent; D000416:Alberta / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype / Q000502:physiology*; D053122:Influenza A Virus, H3N2 Subtype / Q000502:physiology*; D009981:Influenza B virus; D007251:Influenza, Human / Q000453:epidemiology / Q000821:virology*; D008137:Longitudinal Studies; D009297:Nasal Mucosa / Q000821:virology; D010614:Pharynx / Q000821:virology; D033303:Protestantism; D018571:Sentinel Surveillance; D019562:Viral Load; D017201:Virus Shedding