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 epididymitis in men, and represents a substantial public health problem.

Further information on chlamydia is available from NHS.UK.


The National Chlamydia Screening Programme (NCSP) aims to control chlamydia through early detection and treatment of asymptomatic infection to reduce onward transmission and the consequences of untreated infection.

Data collection

Public Health England (PHE) collects data on all chlamydia tests undertaken in England from NHS laboratories, local authorities and NHS commissioned laboratories, to measure screening activity.

HIV & STI web portal: reporting tool.

PHE: protection of personal information and data.


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 & HIV (BASHH) issues guidelines for the diagnosis, treatment and management of all sexually transmitted infections.

National chlamydia screening programme (NCSP): guidelines and resources.

Published 1 January 2011
Last updated 26 February 2016 + show all updates
  1. Added ‘Chlamydia: guidance on reporting in CTAD and GUMCADv2’ under data collection.

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

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

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

  5. 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

  6. First published.