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A screening programme for Chlamydia trachomatis

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VOL: 96, ISSUE: 42, PAGE NO: 8

Louise McLean, BSc, RGN, RM, research nurse, chlamydia research office, genitourinary medicine department, St Mary's Hospital, Portsmouth

Debbie Keane, BA, RGN, research nurse, chlamydia research office, genitourinary medicine department, St Mary's Hospital, Portsmouth

Chlamydia trachomatis is the most common curable sexually transmitted infection in England and Wales (Hughes et al, 1998). However, a large number of cases remain undiagnosed and untreated because most patients are asymptomatic or the infection is associated only with non-specific symptoms.

Chlamydia trachomatis is the most common curable sexually transmitted infection in England and Wales (Hughes et al, 1998). However, a large number of cases remain undiagnosed and untreated because most patients are asymptomatic or the infection is associated only with non-specific symptoms.

In men, the symptoms may include urethral discharge and dysuria. In women, they may include pelvic pain, a vaginal discharge, menstrual disturbances and dysuria.

Rectal infections are usually asymptomatic, but there may be a discharge or discomfort due to proctitis, and pharyngeal infections are also asymptomatic (Central Audit Group in Genitourinary Medicine, 1997).

Untreated C. trachomatis infection may be associated with serious long-term complications and morbidity. These include:

- Pelvic inflammatory disease;

- Tubal damage, which can result in infertility or ectopic pregnancy (Chief Medical Officer's Expert Advisory Group, 1998);

- Transmission to neonates (ophthalmia neonatorum, pneumonitis);

- Epididymo-orchitis;

- Adult conjunctivitis;

- Arthritis (Reiter's syndrome).

Chlamydiae are obligate intracellular pathogens with an incubation period of one to three weeks. Of the 18 distinct serotypes of chlamydia, only C. trachomatis types D-K are responsible for sexually transmitted genital infections and neonatal infections.

Transmission is primarily through sexual intercourse and it is estimated that there is a 66% risk of transmission between regular sexual partners (Chief Medical Officer's Expert Advisory Group, 1998). Vertical transmission can take place during pregnancy or birth.

UK prevalence rates are difficult to determine as estimates are usually based on selected populations, such as people attending genitourinary medicine (GUM) clinics or women seeking to terminate a pregnancy.

Prevalence studies among women in a variety of UK health care settings have confirmed that there are a large number of asymptomatic cases and that these often involve women who are generally not considered to be at risk (Chief Medical Officer's Expert Advisory Group, 1998). The risk factors include:

- Aged under 25;

- Do not use barrier methods of contraception;

- A new sexual partner or more than two sexual partners in one year;

- The presence of another sexually transmitted infection (Central Audit Group in Genitourinary Medicine, 1997).

Concerns about the increasing prevalence of chlamydial infection and its associated morbidity led to the formation of the Chief Medical Officer's Expert Advisory Group on C. trachomatis in 1996.

Its aim was to review the evidence on and consider the practical implications of screening. It recommended the establishment of two pilot sites for chlamydia screening, in Portsmouth and The Wirral (Chief Medical Officer's Expert Advisory Group, 1998).

Previous studies
Evidence from studies carried out in the USA (Scholes et al, 1996) and Sweden (Herrmann et al, 1991) suggests that a population-based screening programme can significantly reduce the morbidity and sequelae associated with chlamydia infection.

Scholes (1996) also found that targeted screening for chlamydia reduced the incidence of pelvic inflammatory disease by 53%.

The Portsmouth pilot
The aim of the pilot was to evaluate the cost, acceptability and feasibility of a widespread opportunistic screening programme for C. trachomatis.

The programme's objectives were to establish the uptake of screening and to identify and treat cases of chlamydial infection, possibly preventing long-term complications. It also aimed to measure prevalence rates, raise public awareness and develop a model for a national screening campaign.

All women aged 16-24 in Portsmouth Health Authority who had ever had sex were eligible to take part. Unless they changed their sexual partner, they were tested only once.

For one year from September 1 last year, women attending more than 100 selected health care sites in the authority for any reason were opportunistically offered a test for chlamydia. These sites included general practices and family planning, antenatal, gynaecology, colposcopy and GUM clinics.

Although women were targeted, men were also contacted through partner notification and some were reached through GUM clinics and special family planning clinics for young people.

The participants were asked to provide a urine specimen to be tested by a nucleic acid amplification technique. This involves the amplification and detection of C. trachomatis using ligase chain reaction to identify a specific DNA sequence in the organism.

This method was chosen because it is quick and easy to perform, is suitable for widespread screening and is non-invasive. It also has excellent sensitivity and specificity, providing accurate results.

The two research nurses involved in the pilot informed all participants of their results by letter or telephone within two weeks. Patients who tested positive were asked to contact the research nurses to make an appointment for counselling, treatment and partner notification at the GUM clinic where they were based, or to make alternative arrangements for treatment. Patients were also offered a sexual health screen to rule out coexisting infections.

The research nurses followed up patients who failed to contact them and informed the test initiator that they had not been treated.

Health education
The research nurses coordinated a local health education campaign, which ran in conjunction with the screening process. It involved the training of health care professionals involved in the screening process and outreach health promotion work at the local university, colleges and schools. The nurses forged close working relationships with local youth workers to gain access to clients who were difficult to reach, such as homeless people.

All aspects of sexual health were promoted, including the role and accessibility of GUM clinics, in an attempt to reduce the stigma associated with sexually transmitted infections and challenge any preconceptions about them. The study was also promoted through local television, radio and newspapers.

Public response
Screening proved highly acceptable, with more than 16,500 women out of a target population of 30,000 being screened. The number of positive results was high, with preliminary results indicating a rate in the region of 10%.

Most of those who tested positive agreed to attend the GUM clinic, which had serious implications in terms of workload. Many women attended with their partners, who were treated at the same time.

Patients' initial reactions were often shock and guilt, and they were usually worried about telling their partners. Most also raised concerns about their fertility.

As the screening programme progressed, patients' appeared to be less shocked and upset by news of a positive outcome. Although it cannot be concluded that this change resulted from the health education campaign, the research nurses believe that local people now have a greater understanding of chlamydia and talk about it more openly.

Nurses are ideally placed to promote increased awareness of C. trachomatis infection and the need to screen young people for it, and the research nurses involved in this pilot study played a crucial role in coordinating it. However, the results of both pilot studies will have to be analysed before a national screening programme can be recommended.

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