title: Chlamydia trachomatis IgG seroprevalence in the general population of the Netherlands in 1996 and in 2007: differential changes by gender and age.
abstract: OBJECTIVE
  Chlamydia trachomatis (CT) reporting rates from sexually transmitted infection clinics and general practitioners have shown a rising trend in the Netherlands. It is unknown to what extent this reflects increased CT transmission or improved case finding. To achieve more insight into the CT epidemic, we explored the CT IgG seroprevalence (a marker of past CT infection) in the general population of the Netherlands in 1996 and in 2007.
  
  
  METHODS
  From two population-based studies in 1996 and 2007, serum samples, demographic and sexual behaviour outcomes were examined, including 1246 men and 1930 women aged 15-39 years. Serum CT IgG antibodies were analysed using the Medac CT IgG ELISA test. Multivariate logistic regression analyses explored the seroprevalence and determinants over time.
  
  
  RESULTS
  The CT IgG seroprevalence was higher in women than in men (10% vs 6%). Among women aged 25-39 years the seroprevalence was lower in 2007 (9%) than in 1996 (14%; adjusted OR (aOR) 0.6, 95% CI 0.4 to 0.8). There was no statistical evidence of a difference in seroprevalence within birth cohorts. Factors associated with seropositivity were male gender (aOR 0.4, 95% CI 0.3 to 0.7), a self-reported history of CT infection (aOR 5.1, 95% CI 2.6 to 10.0), age 25-39 years (aOR 1.7, 95% CI 1.1 to 2.7), non-Western ethnicity (aOR 2.2, 95% CI 1.4 to 3.3) and ≥ 2 recent sexual partners (aOR 2.2, 95% CI 1.3 to 3.5).
  
  
  CONCLUSIONS
  Between 1996 and 2007 the proportion of individuals in the general population with CT IgG antibodies was lower among women aged 25-39 years, but remained similar among younger women and men.
authors.affiliation: Epidemiology & Surveillance Department, Centre for Infectious Disease Control, National Institute of Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: F
authors.initials: F
authors.lastname: van Aar
authors.affiliation: Epidemiology & Surveillance Department, Centre for Infectious Disease Control, National Institute of Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: de Moraes
authors.affiliation: Laboratory of Immunogenetics, Department of Medical Microbiology and Infection Control, VU University Medical Centre, Amsterdam, The Netherlands Institute of Public Health Genomics, Department of Genetics and Cell Biology, Research Institute GROW, Faculty of Health, Medicine & Life Sciences, University of Maastricht, Maastricht, the Netherlands.
authors.forename: S A
authors.initials: SA
authors.lastname: Morré
authors.affiliation: Epidemiology & Surveillance Department, Centre for Infectious Disease Control, National Institute of Public Health and the Environment (RIVM), Bilthoven, The Netherlands STI AIDS Netherlands (SOA AIDS Nederland), Amsterdam, The Netherlands Department of General Practice, AMC-UVA, Amsterdam, The Netherlands.
authors.forename: J E A M
authors.initials: JE
authors.lastname: van Bergen
authors.affiliation: Laboratory for Infectious Disease and Screening, Centre for Infectious Disease Control, National Institute of Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: F R M
authors.initials: FR
authors.lastname: van der Klis
authors.affiliation: Department of Obstetrics and Gynaecology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: J A
authors.initials: JA
authors.lastname: Land
authors.affiliation: Epidemiology & Surveillance Department, Centre for Infectious Disease Control, National Institute of Public Health and the Environment (RIVM), Bilthoven, The Netherlands Julius Centre, UMCU, Utrecht, The Netherlands.
authors.forename: M A B
authors.initials: MA
authors.lastname: van der Sande
authors.affiliation: Epidemiology & Surveillance Department, Centre for Infectious Disease Control, National Institute of Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: I V F
authors.initials: IV
authors.lastname: van den Broek
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000907:Antibodies, Bacterial / Q000097:blood*; D002690:Chlamydia Infections / Q000453:epidemiology* / Q000276:immunology; D002692:Chlamydia trachomatis / Q000276:immunology / Q000302:isolation & purification*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D008297:Male; D009426:Netherlands / Q000453:epidemiology; D011159:Population Surveillance; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D017678:Sex Distribution; D012725:Sexual Behavior / Q000706:statistics & numerical data*; D012747:Sexual Partners
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G
keywords: CHLAMYDIA TRACHOMATIS; EPIDEMIOLOGY (GENERAL); SEROLOGY; SURVEILLANCE