title: Chlamydia trachomatis Pgp3 Antibody Population Seroprevalence before and during an Era of Widespread Opportunistic Chlamydia Screening in England (1994-2012).
abstract: Opportunistic chlamydia screening of <25 year-olds was nationally-implemented in England in 2008 but its impact on chlamydia transmission is poorly understood. We undertook a population-based seroprevalence study to explore the impact of screening on cumulative incidence of chlamydia, as measured by C.trachomatis-specific antibody.
  
  
  
  Anonymised sera from participants in the nationally-representative Health Surveys for England (HSE) were tested for C.trachomatis antibodies using two novel Pgp3 enzyme-linked immunosorbent assays (ELISAs) as a marker of past infection. Determinants of being seropositive were explored using logistic regression among 16-44 year-old women and men in 2010 and 2012 (years when sexual behaviour questions were included in the survey) (n = 1,402 women; 1,119 men). Seroprevalence trends among 16-24 year-old women (n = 3,361) were investigated over ten time points from 1994-2012.
  
  
  
  In HSE2010/2012, Pgp3 seroprevalence among 16-44 year-olds was 24.4% (95%CI 22.0-27.1) in women and 13.9% (11.8-16.2) in men. Seroprevalence increased with age (up to 33.5% [27.5-40.2] in 30-34 year-old women, 18.7% [13.4-25.6] in 35-39 year-old men); years since first sex; number of lifetime sexual partners; and younger age at first sex. 76.7% of seropositive 16-24 year-olds had never been diagnosed with chlamydia. Among 16-24 year-old women, a non-significant decline in seroprevalence was observed from 2008-2012 (prevalence ratio per year: 0.94 [0.84-1.05]).
  
  
  
  Our application of Pgp3 ELISAs demonstrates a high lifetime risk of chlamydia infection among women and a large proportion of undiagnosed infections. A decrease in age-specific cumulative incidence following national implementation of opportunistic chlamydia screening has not yet been demonstrated. We propose these assays be used to assess impact of chlamydia control programmes.
authors.affiliation: National Infection Service, Public Health England, London, United Kingdom.|Research Department of Infection and Population Health, UCL, London, United Kingdom.
authors.forename: Sarah C
authors.identifier: 0000-0001-7896-3526
authors.initials: SC
authors.lastname: Woodhall
authors.affiliation: Jefferiss Research Trust Laboratories, Faculty of Medicine, Imperial College London, St Mary's Campus, London, United Kingdom.
authors.forename: Gillian S
authors.initials: GS
authors.lastname: Wills
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Horner
authors.affiliation: NatCen Social Research, London, United Kingdom.
authors.forename: Rachel
authors.initials: R
authors.lastname: Craig
authors.affiliation: Research Department of Epidemiology and Public Health, UCL, London, United Kingdom.
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Mindell
authors.affiliation: National Infection Service, Public Health England, London, United Kingdom.
authors.forename: Gary
authors.initials: G
authors.lastname: Murphy
authors.affiliation: Jefferiss Research Trust Laboratories, Faculty of Medicine, Imperial College London, St Mary's Campus, London, United Kingdom.
authors.forename: Myra O
authors.initials: MO
authors.lastname: McClure
authors.affiliation: National Infection Service, Public Health England, London, United Kingdom.
authors.forename: Kate
authors.initials: K
authors.lastname: Soldan
authors.affiliation: National Infection Service, Public Health England, London, United Kingdom.
authors.forename: Anthony
authors.initials: A
authors.lastname: Nardone
authors.affiliation: Research Department of Infection and Population Health, UCL, London, United Kingdom.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Johnson
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000907:Antibodies, Bacterial / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D002690:Chlamydia Infections / Q000453:epidemiology* / Q000235:genetics / Q000635:transmission; D002692:Chlamydia trachomatis / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D004739:England / Q000453:epidemiology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D009894:Opportunistic Infections / Q000453:epidemiology* / Q000235:genetics / Q000635:transmission; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D012725:Sexual Behavior; D012747:Sexual Partners; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C082169:pgp3 protein, Chlamydia