title: Viruses associated with acute respiratory infections and influenza-like illness among outpatients from the Influenza Incidence Surveillance Project, 2010-2011.
abstract: BACKGROUND
  The Influenza Incidence Surveillance Project (IISP) monitored outpatient acute respiratory infection (ARI; defined as the presence of ≥ 2 respiratory symptoms not meeting ILI criteria) and influenza-like illness (ILI) to determine the incidence and contribution of associated viral etiologies.
  
  
  METHODS
  From August 2010 through July 2011, 57 outpatient healthcare providers in 12 US sites reported weekly the number of visits for ILI and ARI and collected respiratory specimens on a subset for viral testing. The incidence was estimated using the number of patients in the practice as the denominator, and the virus-specific incidence of clinic visits was extrapolated from the proportion of patients testing positive.
  
  
  RESULTS
  The age-adjusted cumulative incidence of outpatient visits for ARI and ILI combined was 95/1000 persons, with a viral etiology identified in 58% of specimens. Most frequently detected were rhinoviruses/enteroviruses (RV/EV) (21%) and influenza viruses (21%); the resulting extrapolated incidence of outpatient visits was 20 and 19/1000 persons respectively. The incidence of influenza virus-associated clinic visits was highest among patients aged 2-17 years, whereas other viruses had varied patterns among age groups.
  
  
  CONCLUSIONS
  The IISP provides a unique opportunity to estimate the outpatient respiratory illness burden by etiology. Influenza virus infection and RV/EV infection(s) represent a substantial burden of respiratory disease in the US outpatient setting, particularly among children.
authors: Influenza Division.
authors: Ashley
authors: A
authors: Fowlkes
authors: Andrea
authors: A
authors: Giorgi
authors: Dean
authors: D
authors: Erdman
authors: Jon
authors: J
authors: Temte
authors: Kate
authors: K
authors: Goodin
authors: Steve
authors: S
authors: Di Lonardo
authors: Yumei
authors: Y
authors: Sun
authors: Karen
authors: K
authors: Martin
authors: Michelle
authors: M
authors: Feist
authors: Rachel
authors: R
authors: Linz
authors: Rachelle
authors: R
authors: Boulton
authors: Elizabeth
authors: E
authors: Bancroft
authors: Lisa
authors: L
authors: McHugh
authors: Jose
authors: J
authors: Lojo
authors: Kimberly
authors: K
authors: Filbert
authors: Lyn
authors: L
authors: Finelli
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007251:Influenza, Human / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D010045:Outpatients; D011159:Population Surveillance; D012141:Respiratory Tract Infections / Q000821:virology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014481:United States / Q000453:epidemiology; D055815:Young Adult
keywords: acute respiratory illness; epidemiology; influenza; influenza-like illness; respiratory virus; seasonality