You are here

  • Home
  • Archive
  • Volume 93, Issue 4
  • What explains anorectal chlamydia infection in women? Implications of a mathematical model for test and treatment strategies

Article Text

Article menu
Epidemiology
Original article
What explains anorectal chlamydia infection in women? Implications of a mathematical model for test and treatment strategies
  1. Janneke C M Heijne1,
  2. Geneviève A F S van Liere2,3,
  3. Christian J P A Hoebe2,3,
  4. Johannes A Bogaards1,
  5. Birgit H B van Benthem1,
  6. Nicole H T M Dukers-Muijrers2,3
  1. 1Centre for Infectious Diseases Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands
  2. 2Department of Sexual Health, Infectious Diseases and Environmental Health, South Limburg Public Health Service, Geleen, Netherlands
  3. 3Department of Medical Microbiology, Care and Public Health Research Institute (CAPHRI), Maastricht University Medical Center (MUMC+), Maastricht, Netherlands
  1. Correspondence to Dr Janneke Heijne, National Institute of Public Health and the Environment, P. O. Box 1, Bilthoven 3720 BA, The Netherlands; janneke.heijne{at}rivm.nl

Abstract

Objectives Female anorectal Chlamydia trachomatis (chlamydia) infections are common irrespective of recent anal sex. We explored the role of anorectal infections in chlamydia transmission and estimated the impact of interventions aimed at improved detection and treatment of anorectal infections.

Methods We developed a pair compartmental model of heterosexuals aged 15–29 years attending STI clinics, in which women can be susceptible to or infected with chlamydia urogenitally and/or anorectally and men urogenitally. Transmission probabilities per vaginal and anal sex act, together with an autoinoculation probability, were estimated by fitting to anatomic site-specific prevalence data (14% urogenital; 11% anorectal prevalence). We investigated the 10-year reduction in female chlamydia prevalence of interventions (universal anorectal testing of female STI clinic attendees or doxycycline use for urogenital chlamydia) relative to continued current care (anorectal testing on indication and doxycycline for anorectal and azithromycin for urogenital chlamydia).

Results The transmission probability per anal sex act was 5.8% (IQR 3.0–8.3%), per vaginal sex act 2.0% (IQR 1.7–2.2%) and the daily autoinoculation probability was 0.7% (IQR 0.5–1.0%). More anorectal chlamydia infections were caused by autoinoculation than by recent anal sex. Universal anorectal testing reduced population prevalence modestly with 8.7% (IQR 7.6–9.7%), yet the reduction was double that of doxycycline use for urogenital infections (4.3% (IQR 3.5–5.3%)) relative to continued current care.

Conclusions Autoinoculation between anatomic sites in women might play a role in sustaining high chlamydia prevalence. A shift to more anorectal testing of female STI clinic attendees may be considered for its (albeit modest) impact on reducing prevalence.

  • CHLAMYDIA TRACHOMATIS
  • MATHEMATICAL MODEL
  • WOMEN
  • TREATMENT
  • ANOGENITAL CONDITIONS

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

https://doi.org/10.1136/sextrans-2016-052786

Statistics from Altmetric.com

    Request Permissions

    If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

    View Full Text

    Supplementary materials

    • Abstract in Dutch

      This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.

    Footnotes

    • Handling editor Jackie A Cassell

    • Contributors JCMH designed the study, developed the mathematical model, performed the model analyses and drafted the manuscript. GAFSvL, NHTMD-M and CJPAH collected and analysed the data. NHTMDM and BHBvB contributed to the design of the study and JAB to the design of the mathematical model. All authors contributed to the interpretation of the results and commented on the manuscript.

    • Competing interests None declared.

    • Patient consent Obtained.

    • Ethics approval The study was approved by the Medical Ethics Committee of Maastricht University (11-4-108).

    • Provenance and peer review Not commissioned; externally peer reviewed.