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Chlamydia

Introduction

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 15 to 24 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 15 to 24 years.

UK Health Security Agency (UKHSA) recommends that local areas should be working towards achieving a chlamydia detection rate no lower than 3,250 per 100,000 among women aged 15 to 24 years, and this is an indicator in the Public Health Outcomes Framework.

Key findings

The following findings are based on 2025 data:

  • In the Lancashire-12 area, the proportion (13.8%) 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 (16.0%). In Blackburn with Darwen (13.4%) this proportion is significantly lower than the England rate and in Blackpool (27.8%) it is significantly higher than the England rate.

  • Compared to 2023 (19.2%), 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 (20.0% in 2023).

  • With the exception of Burnley (16.4%), Hyndburn (16.1%), Fylde (15.2%) and South Ribble (15.0%), where the proportion of 15-24-year-old females screened for chlamydia is similar to the England rate, in the other eight 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 (1,267) is lower than the recommended target of 3,250 and similar to the England rate (1,348). 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 (1,332) and Blackpool's (2,597) chlamydia detection rate per 100,000 females aged 15 to 24 is also lower than the target of 3,250. Blackburn with Darwen's chlamydia detection rate per 100,000 females aged 15 to 24 is similar to the England rate and Blackpool's rate is significantly higher than the England rate.

  • In 2025, there were 2,499 chlamydia diagnoses in the Lancashire-12 area. Lancashire-12 area's chlamydia diagnostic rate (193 per 100,000 population) is significantly lower than the England rate (258).

  • Blackburn with Darwen's chlamydia diagnostic rate (263) is similar to the England rate and Blackpool's chlamydia diagnostic rate (404) is significantly higher than the England rate.

  • Burnley (233) and Preston's (280) chlamydia diagnostic rate is similar to the England rate; in the other ten Lancashire-12 districts it is significantly lower than the England rate.

For county and unitary data and further information please see below

Page updated July 2026