Chlamydia

Chlamydia is the most common bacterial sexually transmitted infection in England, with rates substantially higher in young adults than any other age group.

By diagnosing and treating asymptomatic chlamydia infections, chlamydia screening can reduce the duration of infection, which will reduce an individual’s chance of developing chlamydia associated complications, and also reduce the amount of time someone is at risk of passing the infection on, which in turn will reduce the spread of chlamydia in the population.

The National Chlamydia Screening Programme (NCSP) promotes opportunistic screening to sexually active young people aged under 25 years.

In June 2021 changes to the programme were announced with a focus on reducing reproductive harm of untreated infection through opportunistic screening offered to young women aged under 25 years.

UK Health Security Agency (UKHSA) recommends that local authorities should be working towards the revised female-only PHOF benchmark detection rate indicator (DRI) of 3,250 per 100,000 aged 15 to 24 (Female).

The following findings are based on 2024 data:

• In the Lancashire-12 area, the proportion (15.3%) of the female population aged 15 to 24 screened for chlamydia, in specialist and non-specialist sexual health services, is significantly lower than the England rate (18.0%). In Blackburn with Darwen (15.7%) this proportion is significantly lower than the England rate and in Blackpool (29.8%) it is significantly higher than the England rate.
• Compared to 2023 (19.1%), there has been a decline in the proportion of 15-24-year-old females screened for chlamydia in the Lancashire-12 area overall and in England (20.1% in 2023).
• With the exception of Fylde (20.5%), in the other 11 districts of the Lancashire-12 area the proportion of 15-24-year-old females screened for chlamydia is significantly lower than the England rate.
• Lancashire-12 area's chlamydia detection rate per 100,000 15-24-year-old females (1,400) is lower than the recommended target of 3,250 and lower than the England rate (1,589). England's chlamydia detection rate per 100,000 15-24-year-old females is also lower than the recommended target of 3,250.
• Blackburn with Darwen's chlamydia detection rate per 100,000 females aged 15 to 24 (1,649) is also lower than the target of 3,250 and similar to the England rate; Blackpool's rate (3,347) is above the recommended target and higher than the England rate.
• In 2024, there were 2,809 chlamydia diagnoses in the Lancashire-12 area. Lancashire-12 area's chlamydia diagnostic rate (221 per 100,000 population) is lower than the England rate (293).
• Blackburn with Darwen's chlamydia diagnostic rate (298) is similar to the England rate, while Blackpool's chlamydia diagnostic rate (514) is higher than the England rate.
• Preston (300) and Lancaster's (280) chlamydia diagnostic rate is significantly higher than the England rate; in the other ten districts it is lower than the England rate.

For county and unitary data and further information please see below

Page updated June 2025