Chlamydia trachomatis Pgp3 Antibody Population Seroprevalence before and during an Era of Widespread Opportunistic Chlamydia Screening in England (1994-2012).

• Main Authors: Sarah C Woodhall, Gillian S Wills, Patrick J Horner, Rachel Craig, Jennifer S Mindell, Gary Murphy, Myra O McClure, Kate Soldan, Anthony Nardone, Anne M Johnson
• Format: Article
• Language: English
• Published: Public Library of Science (PLoS) 2017-01-01
• Series: PLoS ONE
• Online Access: http://europepmc.org/articles/PMC5271337?pdf=render

<label>BACKGROUND</label>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.<label>METHODS</label>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.<label>RESULTS</label>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]).<label>CONCLUSION</label>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.