title: Risk Factors Associated With Bordetella pertussis Among Infants ≤4 Months of Age in the Pre-Tdap Era: United States, 2002-2005.
abstract: In the United States, infants have the highest reported pertussis incidence and death rates. Improved understanding of infant risk factors is needed to optimize prevention strategies.
  
  
  
  We prospectively enrolled infants ≤4 months of age with incident-confirmed pertussis from 4 sites during 2002-2005 (preceding pertussis antigen-containing vaccination recommendations for adolescents/adults); each case-patient was age and site matched with 2 control subjects. Caregivers completed structured interviews. Infants and their contacts ≥11 years of age were offered serologic testing for IgG; being seropositive was defined as ≥94 antipertussis toxin IgG enzyme-linked immunosorbent assay units per milliliter.
  
  
  
  Enrolled subjects (115 case-patients; 230 control subjects) had 4396 contacts during incubation periods; 83 (72%) case-patients had ≥1 contact with prolonged (≥5 days) new cough in primary or secondary households. In multivariable analysis, the odds for pertussis were higher for infants with primary/secondary household contacts who had a prolonged new cough, compared with infants who did not. These contacts included mother [adjusted matched odds ratio (aMOR), 43.8; 95% confidence interval (CI), 6.45-298.0] and ≥1 nonmother contact (aMOR, 20.1; 95% CI, 6.48-62.7). Infants receiving breast milk with 0-1 formula feedings daily had decreased pertussis odds (aMOR, 0.27; 95% CI, 0.08-0.89), compared with those receiving more formula. Of 41 tested case-patients, 37 (90%) were seropositive.
  
  
  
  Pertussis in infants was associated with prolonged new cough (≥5 days) in infants' household contacts. Findings suggest that breastfeeding protects against pertussis and warrants recommendation with pertussis prevention strategies, which currently include pertussis vaccination of pregnant mothers and infants' close contacts.
authors.affiliation: From the *Immunization Services Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; †Preventive Medicine Residency, Population Health Workforce Branch, Division of Scientific Education and Professional Development, Center for Surveillance, Epidemiology, and Laboratory Services, Centers for Disease Control and Prevention, Atlanta, Georgia; ‡Epidemic Intelligence Service Program, Epidemiology Workforce Branch, Division of Scientific Education and Professional Development, Center for Surveillance, Epidemiology, and Laboratory Services, Centers for Disease Control and Prevention, Atlanta, Georgia; §Division of Global HIV & TB, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia; ¶Washington State Department of Health, Shoreline, Washington; ‖Public Health-Seattle & King County, Seattle, Washington; **Arizona Department of Health Services, Phoenix, Arizona; ††Infectious Disease Epidemiology, Prevention, and Control Division, Minnesota Department of Health, St. Paul, Minnesota; ‡‡City of Philadelphia Department of Public Health, Philadelphia, Pennsylvania; §§Meningitis and Vaccine Preventable Diseases Branch, Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; and ¶¶ Epidemiology and Surveillance Division, National Immunization Program, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Christine Robinette
authors.initials: CR
authors.lastname: Curtis
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Baughman
authors.forename: Chas
authors.initials: C
authors.lastname: DeBolt
authors.forename: Susan
authors.initials: S
authors.lastname: Goodykoontz
authors.forename: Cynthia
authors.initials: C
authors.lastname: Kenyon
authors.forename: Barbara
authors.initials: B
authors.lastname: Watson
authors.forename: Pamela K
authors.initials: PK
authors.lastname: Cassiday
authors.forename: Claudia
authors.initials: C
authors.lastname: Miller
authors.forename: Lucia C
authors.initials: LC
authors.lastname: Pawloski
authors.forename: Maria-Lucia C
authors.initials: MC
authors.lastname: Tondella
authors.forename: Kristine M
authors.initials: KM
authors.lastname: Bisgard
mesh_terms: D001886:Bordetella pertussis; D001942:Breast Feeding; D015721:Diphtheria-Tetanus-Pertussis Vaccine; D005260:Female; D006801:Humans; D007115:Immunization Schedule; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011446:Prospective Studies; D012307:Risk Factors; D014481:United States / Q000453:epidemiology; D014917:Whooping Cough / Q000453:epidemiology*
chemical_list: D015721:Diphtheria-Tetanus-Pertussis Vaccine