title: Seasonal incidence of medically attended respiratory syncytial virus infection in a community cohort of adults ≥50 years old.
abstract: BACKGROUND
  Diagnostic testing for respiratory syncytial virus (RSV) is not routinely performed in adults. We estimated medically attended RSV seasonal incidence in a community cohort of adults ≥50 years old during four influenza seasons (2006-07 through 2009-10).
  
  
  METHODS
  Patients seeking care for acute respiratory illness (ARI) were prospectively enrolled and tested for RSV by multiplex RT-PCR. Results from enrolled patients were used to estimate projected cases among non-enrolled patients with ARI. The seasonal incidence of medically attended RSV was the sum of actual and projected cases divided by the community cohort denominator. Since each enrollment period did not include the entire RSV season, incidence estimates were adjusted to account for the statewide proportion of RSV occurring outside the study enrollment period.
  
  
  RESULTS
  There were 16,088 to 17,694 adults in the cohort each season and 164 RSV cases in all 4 seasons. The overall seasonal incidence of medically attended RSV was 154 episodes (95% CI, 132-180) per 10,000 persons; the incidence was highest in 2007-08 (179) and lowest in 2006-07 (110). Among persons 50-59, 60-69, and ≥70 years old, RSV incidence was 124 (95% CI, 99-156), 147 (95% CI, 110-196), and 199 (95% CI, 153-258), respectively.
  
  
  CONCLUSIONS
  The incidence of medically attended RSV increased with age and was similar during four seasons.
authors.affiliation: Marshfield Clinic Research Foundation, Marshfield, Wisconsin, United States of America.
authors.forename: David L
authors.initials: DL
authors.lastname: McClure
authors.affiliation: Marshfield Clinic Research Foundation, Marshfield, Wisconsin, United States of America.
authors.forename: Burney A
authors.initials: BA
authors.lastname: Kieke
authors.affiliation: Marshfield Clinic Research Foundation, Marshfield, Wisconsin, United States of America.
authors.forename: Maria E
authors.initials: ME
authors.lastname: Sundaram
authors.affiliation: Marshfield Clinic Research Foundation, Marshfield, Wisconsin, United States of America.
authors.forename: Melissa D
authors.initials: MD
authors.lastname: Simpson
authors.affiliation: Marshfield Clinic Research Foundation, Marshfield, Wisconsin, United States of America.
authors.forename: Jennifer K
authors.initials: JK
authors.lastname: Meece
authors.affiliation: MedImmune LLC, Gaithersburg, Maryland, United States of America.
authors.forename: Frangiscos
authors.initials: F
authors.lastname: Sifakis
authors.affiliation: MedImmune LLC, Gaithersburg, Maryland, United States of America.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Gasser
authors.affiliation: Marshfield Clinic Research Foundation, Marshfield, Wisconsin, United States of America.
authors.forename: Edward A
authors.initials: EA
authors.lastname: Belongia
mesh_terms: D000328:Adult; D000368:Aged; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000628:therapy; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012111:Residence Characteristics; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology* / Q000628:therapy; D012621:Seasons; D014922:Wisconsin / Q000453:epidemiology