About this release

This publication by Public Health Scotland (PHS) presents information on Chlamydia trachomatis infection in Scotland to the end of December 2022. The report provides ten-year data trends and presents data observed during the COVID-19 pandemic which impacted significantly on the routes through which individuals have been able to access sexual health services.

Main points

  • In 2022, there were 13,148 diagnoses of chlamydia in Scotland. This is higher than the previous two years where testing was affected by the COVID-19 pandemic but lower when compared to 2019 (17,336).
  • The incidence of diagnosed chlamydia infection has increased gradually since the COVID-19 pandemic but has not reached the levels observed prior to the pandemic.
  • Over half (56%) of diagnoses in 2022 were in women (7,368).
  • In 2022, 72% of diagnoses in women were in those aged less than 25 years compared to 50% in men. Historically, the majority of chlamydia diagnoses in women have been in those aged less than 25 years, while in men, diagnoses are distributed across all age groups.
  • At the end of December 2022, the number of individuals tested for chlamydia in sexual health clinics has not yet recovered to that observed prior to the COVID-19 pandemic.
  • There were 2,552 positive individuals per 10,000 people tested in the last quarter of 2022, consistent with the quarterly incidence before the COVID-19 pandemic.
  • In 2022, in the sexual health clinic setting, the incidence of diagnosed chlamydia infection was highest among heterosexual men, followed by women and then gay, bisexual and other men who have sex with men (GBMSM). This is similar to observations made before the COVID-19 pandemic. There has been a small increase in incidence observed in heterosexual men and women tested in sexual health clinics through 2021 and 2022.
Image caption Incidence of diagnosed Chlamydia trachomatis infection per 100,000 persons per month in Scotland, 2018-2022

Data source: ECOSS

Incidence is based on number of positives per 100,000 population aged 15-64 years using the National Records for Scotland estimate as at 30 June 2021.


Genital chlamydia is caused by infection with Chlamydia trachomatis and is the most common bacterial sexually transmitted infection in Scotland and the UK. Often asymptomatic, chlamydia is spread via unprotected sexual (including vaginal, anal or oral) intercourse with an infected partner. Chlamydial infection can be treated with antibiotics, but if left untreated can lead to reproductive morbidities in women including pelvic inflammatory disease (PID), ectopic pregnancy and tubal factor infertility, while men can suffer from epididymitis.

Further information

The next release of this publication will be April 2024.

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Older versions of this publication

Versions of this publication released before 16 March 2020 may be found on the Data and Intelligence, Health Protection Scotland or Improving Health websites.

Last updated: 21 March 2024
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