Chlamydia: surveillance, data, screening and management

The surveillance, epidemiology, screening and prevention of chlamydia.

Genital chlamydia infection is caused by the Chlamydia trachomatis bacterium which is the most common bacterial sexually transmitted infection in the UK. The prevalence of infection is highest in young sexually active adults (15 to 24 years olds).

Chlamydia often has no symptoms but can lead to a wide range of complications, including pelvic inflammatory disease (PID), ectopic pregnancy and tubal factor infertility (TFI) in women, and represents a substantial public health problem.

Further information on chlamydia is available from NHS.UK.


The aim of the National Chlamydia Screening Programme (NCSP) is focused on reducing the harms from untreated chlamydia infection. The harmful effects of chlamydia occur predominantly in women so the opportunistic screening (that is the proactive offer of a chlamydia test to young people without symptoms) should focus on women, combined with:

  • reducing time to test results and treatment
  • strengthening partner notification
  • re-testing after treatment

Women and other people with a womb or ovaries include transgender men, and non-binary people assigned female at birth, and intersex people with a womb or ovaries.


Diagnosis and management

Laboratory diagnosis is currently achieved using nucleic acid amplification tests (NAATs) which are highly sensitive and specific. These tests allow the use of non-invasive samples, such as urine and self-taken vulvo-vaginal swabs, so are ideal for screening programmes. However, although chlamydia infection can be diagnosed easily, because many infections are asymptomatic a large proportion of cases remain undiagnosed.

The British Association for Sexual Health and HIV (BASHH) issues guidelines for the diagnosis, treatment and management of all sexually transmitted infections.

Guidance on detecting gonorrhoea, including dual NAATs for chlamydia and gonorrhoea.

Information, data, guidance and resources on the National Chlamydia Screening Programme (NCSP)

Published 1 January 2011
Last updated 22 March 2022 + show all updates
  1. Updated links and information on chlamydia.

  2. Added ‘Chlamydia: guidance on reporting in CTAD and GUMCADv2’ under data collection.

  3. Added ‘CTAD: specification and technical guidance’.

  4. Added 'Chlamydia screening: re-testing local monitoring tool'.

  5. The 'National Chlamydia Screening programme: audit report' has been added.

  6. The following have been added under screening: Chlamydia detection rate: considerations for commissioning; Chlamydia: integrating screening into primary care and sexual health services; Chlamydia screening in general practice and community pharmacies

  7. First published.