title: Respiratory pathogens in respiratory tract illnesses during the first year of life: a birth cohort study.
abstract: BACKGROUND
  Respiratory virus infections are the most important trigger of respiratory illnesses in childhood. Data on the occurrence and the clinical impact of respiratory pathogens in the general population of infants are scarce. Therefore, we described the occurrence and clinical impact of respiratory pathogens in infants with respiratory tract infections during the first year of life.
  
  
  METHODS
  In a prospective birth cohort study, infants were followed from birth through the first year of life with daily questionnaires about respiratory symptoms. Nose and throat swabs were collected during episodes with respiratory symptoms. Polymerase chain reaction was used to detect an extensive panel of respiratory pathogens.
  
  
  RESULTS
  The parents reported a median of 5 respiratory episodes per infant per year. A total of 668 respiratory samples were collected in 305 infants. One or more respiratory pathogens were detected in 85% of the samples. The most common respiratory pathogens were human rhinovirus (HRV) (73% of the samples), respiratory syncytial virus (RSV) (11%), and coronavirus (8%). HRV infections were associated with a prolonged period of symptoms compared with RSV (P = 0.03). Infections with RSV were associated with more physician visits than HRV infections (P = 0.06).
  
  
  CONCLUSIONS
  We found a high prevalence of respiratory pathogens among infants with parent-reported respiratory illnesses in the first year of life, with HRV being the most prevalent. Although RSV infections seemed to be responsible for the most severe symptoms compared with HRV, the overall burden of disease was highest for HRV infections.
authors.affiliation: Wilhelmina Children's Hospital, University Medical Center Utrecht, The Netherlands. M.M.vanderZalm@umcutrecht.nl
authors.forename: Marieke M
authors.initials: MM
authors.lastname: van der Zalm
authors.forename: Cuno S P M
authors.initials: CS
authors.lastname: Uiterwaal
authors.forename: Berry
authors.initials: B
authors.lastname: Wilbrink
authors.forename: Brita M
authors.initials: BM
authors.lastname: de Jong
authors.forename: Theo J M
authors.initials: TJ
authors.lastname: Verheij
authors.forename: Jan L L
authors.initials: JL
authors.lastname: Kimpen
authors.forename: Cornelis K
authors.initials: CK
authors.lastname: van der Ent
mesh_terms: D015331:Cohort Studies; D003139:Common Cold / Q000453:epidemiology / Q000821:virology; D017934:Coronavirus / Q000302:isolation & purification / Q000472:pathogenicity; D018352:Coronavirus Infections / Q000453:epidemiology / Q000821:virology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016015:Logistic Models; D008297:Male; D016133:Polymerase Chain Reaction; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology / Q000821:virology; D018113:Respiratory Syncytial Virus, Human / Q000302:isolation & purification / Q000472:pathogenicity; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000821:virology*; D012229:Rhinovirus / Q000302:isolation & purification / Q000472:pathogenicity; D012621:Seasons; D018709:Statistics, Nonparametric