title: Seroprevalence of Bordetella pertussis antibody in children and adolescents in China.
abstract: BACKGROUND
  This multicenter study was undertaken to investigate the serologic evidence of antibodies to Bordetella pertussis toxin (IgG-PT) in children and adolescents.
  
  
  METHODS
  IgG-PT value in a single serum collected from 1616 children and adolescents was measured by enzyme-linked immunosorbent assay in the Food and Drug Administration (FDA)-units per milliliter from November 2008 to October 2009. The relationship between time since infection and IgG anti-PT levels were analyzed and the estimated age-specific incidences of infection were calculated.
  
  
  RESULTS
  The sera IgG-PT geometric mean concentrations of the samples were 1.7 FDA-U/mL. The sera protective rates of all the subjects were 6.6% (95% confidential interval [CI]: 5.4%, 7.8%). The rates in the group aged 2 years was 9.2% (95% CI: 3.5%, 14.9%), which was significantly higher than in those aged ≥ 3 years (χ = 1615, P = 0.000). In the group aged ≥ 3 years, 4.0% (95% CI: 3.0%, 5.0%) of the individuals tested showed an IgG-PT level ≥ 40 FDA-U/mL, which was equivalent to an estimated incidence of B. pertussis infection of 7000 (95% CI: 5300, 8800) per 100,000 population per year in the year before serum sampling. There were 2 peaks of estimated incidence. One peak incidence of 9100 (95% CI: 4300, 14000) per 100,000 population per year was found in the population aged >6 to 8 years. Another peak was in the population of 12- to 20-year olds with the estimated incidence of 14,600 (95% CI: 9100, 20100) per 100,000 per year.
  
  
  CONCLUSIONS
  The levels of protective antibodies against pertussis were very low in the immunized children aged 2 to 20 years. A booster dose of immunization for older children or adolescents should be an urgent priority. Moreover, using enzyme-linked immunosorbent assay to determine the efficiency of vaccines and even to obtain the serodiagnosis would be beneficial in controlling pertussis.
authors.affiliation: The Clinical Microbiology Lab, Department of Nosocomial Infection Control, The Children's Hospital of Fudan University, Shanghai, China.
authors.forename: Chuan-Qing
authors.initials: CQ
authors.lastname: Wang
authors.forename: Qi-Rong
authors.initials: QR
authors.lastname: Zhu
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000907:Antibodies, Bacterial / Q000097:blood*; D001886:Bordetella pertussis / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D015994:Incidence; D008297:Male; D016036:Seroepidemiologic Studies; D014917:Whooping Cough / Q000453:epidemiology*; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G