title: Infant pertussis: who was the source?
abstract: BACKGROUND
  In the United States in the 1990s, the incidence of reported pertussis in adults, adolescents and infants increased; infants younger than 1 year of age had the highest reported incidence.
  
  
  METHODS
  In 4 states with Enhanced Pertussis Surveillance, we examined the epidemiology of reported pertussis cases to determine the source of pertussis among infants. A source was defined as a person with an acute cough illness who had contact with the case-infant 7-20 days before the infant's onset of cough.
  
  
  RESULTS
  The average annual pertussis incidence per 100,000 infants younger than 1 year of age varied by state: 22.9 in Georgia; 42.1 in Illinois; 93.0 in Minnesota; and 35.8 in Massachusetts. Family members of 616 (80%) of 774 reported case-infants were interviewed; a source was identified for 264 (43%) of the 616 case-infants. Among the 264 case-infants, mothers were the source for 84 (32%) and another family member was the source for 113 (43%). Of the 219 source-persons with known age, 38 (17%) were age 0-4 years, 16 (7%) were age 5-9 years, 43 (20%) were age 10-19 years, 45 (21%) were age 20-29 years and 77 (35%) were age > or =30 years.
  
  
  CONCLUSIONS
  The variation in reported pertussis incidence in the 4 states might have resulted from differences in awareness of pertussis among health care providers, diagnostic capacity and case classification. Among case-infants with an identifiable source, family members (at any age) were the main source of pertussis. Understanding the source of pertussis transmission to infants may provide new approaches to prevent pertussis in the most vulnerable infants.
authors.affiliation: Bacterial Vaccine Preventable Diseases Branch, National Immunization Program, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Kristine M
authors.initials: KM
authors.lastname: Bisgard
authors.forename: F Brian
authors.initials: FB
authors.lastname: Pascual
authors.forename: Kristen R
authors.initials: KR
authors.lastname: Ehresmann
authors.forename: Claudia A
authors.initials: CA
authors.lastname: Miller
authors.forename: Christy
authors.initials: C
authors.lastname: Cianfrini
authors.forename: Charles E
authors.initials: CE
authors.lastname: Jennings
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Rebmann
authors.forename: Julie
authors.initials: J
authors.lastname: Gabel
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Schauer
authors.forename: Susan M
authors.initials: SM
authors.lastname: Lett
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D002353:Carrier State; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D018563:Disease Notification; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D007115:Immunization Schedule; D015994:Incidence; D007223:Infant; D008297:Male; D008875:Middle Aged; D010567:Pertussis Vaccine / Q000008:administration & dosage; D018570:Risk Assessment; D017678:Sex Distribution; D014481:United States / Q000453:epidemiology; D014917:Whooping Cough / Q000175:diagnosis* / Q000453:epidemiology* / Q000517:prevention & control
chemical_list: D010567:Pertussis Vaccine