title: Bordetella pertussis is an uncommon pathogen in children hospitalized with bronchiolitis during the winter season.
abstract: BACKGROUND
  In the United States (U.S.), Bordetella pertussis incidence has increased. Cough and apnea are common findings in pertussis and also in bronchiolitis, the most common cause of hospitalization in U.S. infants. The objective was to determine the prevalence of B. pertussis infection in children hospitalized with bronchiolitis and to describe its clinical course.
  
  
  METHODS
  Children hospitalized with bronchiolitis and age <2 years were eligible for a prospective, multicenter cohort study during 3 consecutive winter seasons (November-March) from 2007 to 2010. Sixteen sites in 12 states participated using a standardized enrollment protocol. Families were asked the 2010 Centers for Disease Control and Prevention pertussis classification questions. Nasopharyngeal aspirates were obtained and tested by real-time polymerase chain reaction for 16 viruses, Mycoplasma pneumoniae and B. pertussis.
  
  
  RESULTS
  Two thousand sixty-eight (94%) of 2207 children had 1 or more respiratory pathogens. B. pertussis was identified in 4 children [0.2%; 95% confidence interval (CI): 0.1-0.5%] with 3 having a viral co-infection. All 4 were younger than 4 months; 2 met the Centers for Disease Control and Prevention definition of probable pertussis; and 3 had received at least 1 dose of an acellular pertussis vaccine. During the hospitalization, 2 had paroxysmal cough, 1 required intensive care unit care and the median length of stay was 13 days.
  
  
  CONCLUSIONS
  Our data support that B. pertussis is an uncommon pathogen in U.S. children hospitalized with bronchiolitis in the winter. Making a diagnosis of pertussis can be challenging because the disease can be atypical and may not meet the Centers for Disease Control and Prevention definition of probable infection.
authors.affiliation: From the Departments of *Molecular Virology and Microbiology and †Pediatrics, Baylor College of Medicine, Houston, TX; ‡Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA; §Department of Paediatrics, University of Auckland, Auckland, New Zealand; and ¶Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA.
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Piedra
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Mansbach
authors.forename: Alan M
authors.initials: AM
authors.lastname: Jewell
authors.forename: Sneha D
authors.initials: SD
authors.lastname: Thakar
authors.forename: Cameron C
authors.initials: CC
authors.lastname: Grant
authors.forename: Ashley F
authors.initials: AF
authors.lastname: Sullivan
authors.forename: Janice A
authors.initials: JA
authors.lastname: Espinola
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Camargo
mesh_terms: D001886:Bordetella pertussis / Q000302:isolation & purification*; D001988:Bronchiolitis / Q000453:epidemiology* / Q000382:microbiology*; D015331:Cohort Studies; D005260:Female; D006760:Hospitalization; D006801:Humans; D007223:Infant; D008297:Male; D009177:Mycoplasma pneumoniae / Q000302:isolation & purification; D009305:Nasopharynx / Q000382:microbiology; D015995:Prevalence; D011446:Prospective Studies; D060888:Real-Time Polymerase Chain Reaction; D012621:Seasons; D014481:United States / Q000453:epidemiology; D014780:Viruses / Q000145:classification / Q000302:isolation & purification; D014917:Whooping Cough / Q000453:epidemiology* / Q000382:microbiology