Chlamydia trachomatis infection in Scotland
2014 to 2023

About this release

This publication by Public Health Scotland (PHS) presents information on Chlamydia trachomatis infection in Scotland to the end of December 2023. 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 2023, there were 13,400 diagnoses of chlamydia in Scotland. Diagnoses are higher than last year which was the first post COVID-19 pandemic year but still considerably lower than in 2019 (17,336).   
• In 2023, 55% of chlamydia diagnoses were observed in women (7,392).  
• In 2023, the majority (72%) of diagnoses in women were in those aged less than 25 years compared to 48% in men. Historically, in women, chlamydia diagnoses have been observed in those aged less than 25 years compared to men where diagnoses are distributed more equally across all age groups. 
• In 2023, the number of individuals tested in sexual health clinics has gradually increased since 2020 and testing numbers are now similar to before the COVID-19 pandemic.
• In 2023, the number of individuals who tested positive in the sexual health clinic setting has stabilised since 2022 and reached similar levels to prior the COVID-19 pandemic.
• In 2023, in the sexual health clinic setting, the highest rate of chlamydia diagnoses was observed in heterosexual men, followed by women and gay, bisexual, and other men who have sex with men (GBMSM). A similar pattern was observed in the previous year.

Figure one is a line chart presenting the monthly incidence per 100,000 persons from 2019 to 2023. Incidence fell in March 2020 and has increased since. Incidence is lower compared to 2019.

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Figure 1: Incidence of diagnosed Chlamydia trachomatis infection per 100,000 persons per month in Scotland, 2019-2023

Data source: ECOSS

Background

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 June 2025.