title: Human parainfluenza virus-associated hospitalizations among children less than five years of age in the United States.
abstract: BACKGROUND
  Human parainfluenza viruses 1 through 3 (HPIV-1-3) are important causes of respiratory tract infections in young children. This study sought to provide current estimates of HPIV-1-3-associated hospitalizations among US children.
  
  
  METHODS
  Hospitalizations for bronchiolitis, bronchitis, croup and pneumonia among children age <5 years were determined for the years 1979 through 1997 using the National Hospital Discharge Survey. Average annual hospitalizations during the last 4 years of the study for each of these four diseases were multiplied by the proportions of each disease associated with HPIV-1-3 infection (as previously reported in hospital-based studies) to estimate hospitalizations potentially associated with HPIV-1-3 infections. Seasonal trends in HPIV-1-3-associated hospitalizations were compared with HPIV detections in the National Respiratory and Enteric Virus Surveillance System, which prospectively monitors respiratory viral detections throughout the United States.
  
  
  RESULTS
  The proportions of hospitalizations associated with HPIV infection for each disease varied widely in the 6 hospital-based studies we selected. Consequently our annual estimated rates of hospitalization were broad: HPIV-1, 0.32 to 1.59 per 1,000 children; HPIV-2, 0.10 to 0.86 per 1,000 children; and HPIV-3, 0.48 to 2.6 per 1,000 children. Based on these data HPIV-1 may account for 5,800 to 28,900 annual hospitalizations; HPIV-2 for 1,800 to 15,600 hospitalizations; and HPIV-3 for 8,700 to 52,000 hospitalizations.
  
  
  CONCLUSIONS
  We provide broad, serotype-specific estimates of US childhood hospitalizations associated with HPIV infections. More precise estimates of HPIV-associated hospitalizations would require large prospective studies of HPIV-associated diseases by more sensitive viral testing methods, such as polymerase chain reaction techniques.
authors.affiliation: Rollins School of Public Health, Emory University, Atlanta, GA, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Counihan
authors.forename: D K
authors.initials: DK
authors.lastname: Shay
authors.forename: R C
authors.initials: RC
authors.lastname: Holman
authors.forename: S A
authors.initials: SA
authors.lastname: Lowther
authors.forename: L J
authors.initials: LJ
authors.lastname: Anderson
mesh_terms: D001990:Bronchiolitis, Viral / Q000175:diagnosis / Q000453:epidemiology*; D002675:Child, Preschool; D003440:Croup / Q000175:diagnosis / Q000453:epidemiology*; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D010222:Parainfluenza Virus 1, Human / Q000302:isolation & purification; D010223:Parainfluenza Virus 2, Human / Q000302:isolation & purification; D010224:Parainfluenza Virus 3, Human / Q000302:isolation & purification; D011024:Pneumonia, Viral / Q000175:diagnosis / Q000453:epidemiology*; D010253:Respirovirus Infections / Q000175:diagnosis / Q000453:epidemiology*; D012307:Risk Factors; D012621:Seasons; D012959:Socioeconomic Factors; D014481:United States / Q000453:epidemiology