title: Seroprevalence of pertussis in The Netherlands: evidence for increased circulation of Bordetella pertussis.
abstract: BACKGROUND
  In many countries, the reported pertussis has increased despite high vaccination coverage. However, accurate determination of the burden of disease is hampered by reporting artifacts. The infection frequency is more reliably estimated on the basis of the prevalence of high IgG concentrations against pertussis toxin (IgG-Ptx). We determined whether the increase in reported pertussis in the last decade is associated with an increase in the number of infections.
  
  
  RESULTS
  In a cross-sectional population-based serosurveillance study conducted in 2006-07, from a randomly selected age-stratified sample of 7,903 persons, serum IgG-Ptx concentrations were analyzed using a fluorescent bead-based multiplex immuno assay. In 2006-07, 9.3% (95%CI 8.5-10.1) of the population above 9 years of age had an IgG-Ptx concentration above 62.5 EU/ml (suggestive for pertussis infection in the past year), which was more than double compared to 1995-96 (4.0%; 95%CI 3.3-4.7). The reported incidence showed a similar increase as the seroprevalence between both periods.
  
  
  CONCLUSIONS
  Although changes in the vaccination program have reduced pertussis morbidity in childhood, they have not affected the increased infection rate in adolescent and adult pertussis. Indeed, the high circulation of B. pertussis in the latter age-categories may limit the effectiveness of pediatric vaccination.
authors.affiliation: Epidemiology and Surveillance, Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, The Netherlands. sabine.de.greeff@rivm.nl
authors.forename: Sabine C
authors.initials: SC
authors.lastname: de Greeff
authors.forename: Hester E
authors.initials: HE
authors.lastname: de Melker
authors.forename: Pieter G M
authors.initials: PG
authors.lastname: van Gageldonk
authors.forename: Joop F P
authors.initials: JF
authors.lastname: Schellekens
authors.forename: Fiona R M
authors.initials: FR
authors.lastname: van der Klis
authors.forename: Liesbeth
authors.initials: L
authors.lastname: Mollema
authors.forename: Frits R
authors.initials: FR
authors.lastname: Mooi
authors.forename: Guy A M
authors.initials: GA
authors.lastname: Berbers
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001886:Bordetella pertussis / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007118:Immunoassay; D007074:Immunoglobulin G / Q000378:metabolism; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D037342:Pertussis Toxin; D010567:Pertussis Vaccine / Q000627:therapeutic use*; D016036:Seroepidemiologic Studies; D014917:Whooping Cough / Q000097:blood / Q000453:epidemiology*
chemical_list: D007074:Immunoglobulin G; D010567:Pertussis Vaccine; D037342:Pertussis Toxin