Introduction

Chlamydia is one of the most common sexually transmitted infections (STIs) and is on the rise in the UK, with cases rising by 24.3% from 2021 to 2022.¹ It is estimated that every year there are 131 million new infections of chlamydia.² It can cause uncomfortable symptoms, such as unusual discharge, but many individuals with chlamydia are asymptomatic and are unaware that they have it. Untreated infections can cause long-term health conditions.

There are government schemes in place, such as the National Chlamydia Screening Programme, which offer proactive screening of chlamydia to reduce the number of untreated infections. Prevention campaigns have been published by Public Health England to raise awareness. Control measures are recommended by the European Centre for Disease Prevention and Control. Chlamydia is preventable by using barrier protection.  

The surveillance of chlamydia infections, and promotion of prevention and recommended control measures are all public health strategies in place to try to tackle the rising number of chlamydia cases. 

What is chlamydia?

Chlamydia is an infection which is passed on through unprotected sex or contact with infected genital fluids (semen or vaginal fluid). It is caused by the bacterium Chlamydia trachomatis. The infection tends to be more common in sexually active teenagers and young adults. A lot of people who have chlamydia are unaware they have it as they do not develop symptoms (are asymptomatic).

Individuals who do experience symptoms may experience:

• Unusual discharge from the vagina, penis, or bottom
• Pain when peeing
• Individuals assigned female at birth (AFAB) may experience abdominal pain, bleeding between periods, and bleeding after sex
• Individuals assigned male at birth (AMAB) may experience pain and swelling in the testicles

Chlamydia is treated by taking a course of antibiotics. It is important for individuals who suspect they have chlamydia to visit a GP, community contraceptive service, or local genitourinary medicine (GUM) clinic and get STI tested if they think they may be at risk of having an STI. Regular check-ups for sexually active individuals are recommended, particularly when becoming sexually active with a new partner.

If a chlamydia infection goes untreated, it can lead to complications and cause issues such as pelvic inflammatory disease (PID) and infertility. Long-term health problems caused by untreated chlamydia are more common in people assigned female at birth.

Surveillance 

One public health strategy to control the prevalence of chlamydia is surveillance and screening. Assessing chlamydia prevalence through detection and treatment can provide insight into infection levels. It also produces information on the demographics where chlamydia is most prevalent. This information can be used to create targeted strategies to reduce chlamydia levels. 

It is recommended that people assigned female at birth who are sexually active should have a chlamydia test once a year, and when they have sex with new or casual partners. People assigned male at birth who are sexually active are recommended to have a chlamydia test once a year if they are not using condoms with new or casual partners. These guidelines are published on the NHS website and are conveyed to individuals by healthcare professionals.

As most individuals with chlamydia are asymptomatic, screening is a way of identifying and diagnosing individuals who may have no outward signs that they have a chlamydia infection.

In the UK, the National Chlamydia Programme (NCSP)  focuses on reducing the harmful effects that an untreated chlamydia infection can cause.³ As AFAB people more frequently experience the harmful effects of chlamydia, the scheme focuses on AFAB individuals.

In this scheme, young people (specifically AFAB people) are proactively offered a chlamydia test without having symptoms. This occurs in community settings, such as GPs and pharmacies. One of the scheme’s main focuses is reducing the time to test results and treatments as this can reduce the risk of harmful effects. An evaluation of this scheme found that the proportion of chlamydia infections detected increased for all socio-demographic and self-reported sexual behaviour groups. This was found both during and after the campaign.⁴

The CTAD Chlamydia Surveillance System is the government's report on chlamydia testing and detection in England. The report covers in detail at national and local levels screening coverage, the proportion of positive chlamydia tests, and the chlamydia detection rate. The UK Health Security Agency (UKHSA, formerly Public Health England) combines the CTAD data with the GUMCAD Surveillance System to report on chlamydia testing activity.

The use of schemes to screen young people who are showing no symptoms can improve treatment rates and decrease the incidence of the long term effects of untreated chlamydia. Additionally, treating an increased number of cases from increased screening and detection can help to prevent the spread of infection. In turn, this can reduce the number of new infections.

Prevention 

Any sexually active individual is at risk of catching chlamydia; however, it is preventable. Individuals who do not use a barrier method of contraception (such as a condom), or who have a new sexual partner are the most at risk. A barrier, such as a condom or a dam (a thin piece of thin, soft plastic or latex that covers the female genitals), should be consistently used during sexual activity. Guidance on prevention can be found on the NHS website. 

Public Health England (PHE, now the UKHSA) has produced campaigns as part of national sexual health prevention. One campaign they launched was ‘Protect against STIs’ in 2017 which aimed to raise awareness of STIs and encourage the use of condoms. This campaign consisted of a range of campaign advertising and images.

Promoting prevention is an effective method of reducing the number of new cases of chlamydia. If more individuals are aware of negative effects and prevention methods, it can help to normalise  safe sex practices. With a lower number of new cases and higher detection of infections, the overall incidence of chlamydia infections could decrease.

Control measures

Without having control measures in place, STI levels can rapidly increase and have a significant impact on the public and on health services. The current control measures in place for chlamydia are in line with recommendations by the European Centre for Disease Prevention and Control (ECDC). These recommendations were published when the United Kingdom was still a EU/EEA Member State. 

The ECDC recommends that EU/EEA Member States should have a national strategy or plan for the control of STIs such as chlamydia. This strategy should include primary prevention interventions targeted towards at-risk individuals. It also calls for improved surveillance of diagnosed infections. In the UK, this is covered by the National Chlamydia Program and the CTAD and GUMCAD data. 

The strategy also calls for evidence-based chlamydia case management guidelines. These should address criteria for testing, diagnostic methods, treatment, partner notification and reporting of cases.⁵ Partner notification is an effective way to target testing to individuals who are at risk of having chlamydia. 

These control measures aim to keep the incidence of chlamydia infections from rising. 

Summary

Chlamydia is one of the most prevalent STIs in the UK with rising numbers of cases. Many individuals with chlamydia are asymptomatic so are unaware of the infection. Individuals with symptoms may experience unusual discharge, pain when peeing, abdominal or testicular pain, and bleeding after sex. If a chlamydia infection goes untreated it can cause many complications, including pelvic inflammatory disease. It is more common for people assigned female at birth to experience long-term health effects. 

The surveillance of chlamydia testing, proportion of positive tests and treatment can provide a lot of information about chlamydia infection levels and demographics where it is more prevalent. This information can help create targeted strategies to reduce infection levels. The NCSP is a national program that proactively offers screening to young people to try to reduce the levels of untreated chlamydia infections. This program predominantly focuses on people assigned female at birth. 

Chlamydia is preventable by consistently and correctly using protection during sexual activity. Promoting prevention is a key strategy to controlling chlamydia levels. The UKHSA/Public Health England has created campaigns to encourage and normalise using protection.

The ECDC has published recommendations for control measures for EU/EEA Member States to try to control levels of STIs including chlamydia. This involves primary prevention interventions, surveillance and screening and evidence-based case management. All of these public health strategies work together to try to control the levels of chlamydia infections and reduce the incidence of individuals experiencing the harmful long term effects of an untreated chlamydia infection.