Blood Borne Viruses & Sexually Transmitted Infections

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Weekly Report Articles

26 September 2017

Genital chlamydia and gonorrhoea infection in Scotland: laboratory diagnoses 2007 - 2016

Key points

  • In 2016, diagnoses of genital chlamydia and gonorrhoea have remained at the same level as that reported in 2015.
  • Young people, particularly women aged under 25, are the group most at risk of being diagnosed with an STI.
  • Rectal gonorrhoea in men, a marker of condomless anal intercourse, has remained high.


In this report, ten-year trend data are presented on two acute sexually transmitted infections (STIs): genital chlamydia and gonorrhoea.

Data on genital chlamydia and gonorrhoea infection are extracted from the laboratory diagnoses database, the Electronic Communication of Surveillance in Scotland System (ECOSS).1 This is an HPS surveillance system which is updated daily with positive test results from all Scottish diagnostic and reference laboratories.

The universal use of ECOSS by testing laboratories in Scotland has resulted in a greater quantity and better quality of data which is subject to cleaning and refinement at HPS. Thus, the trends observed since 2009 and the implementation of ECOSS in all laboratories are not directly comparable to those prior to this date. The data associated with the laboratory-positive diagnoses are restricted to age, gender and the NHS board where the clinical specimen originated. Records of infection in those aged under 10 are not reported.

Some numbers in this report have been suppressed – as indicated with an asterisk (*) – in instances where patient confidentiality might be compromised through deductive disclosure.

Genital chlamydia

In 2016, 15,147 diagnoses of genital chlamydial infection were reported to HPS, a similar number to that reported in 2015 (15,000). The total number of diagnoses has been reducing in recent years but appears to be stable at around 15,000 diagnoses annually during the past two years (Table 1). The improved data capture of laboratory test results via ECOSS means that the data since 2009 have been subject to more extensive validation, particularly with regard to removing repeat samples taken for the same episode of infection. The data presented in this report for genital (including extragenital) chlamydial infection indicate episodes of infection, where an episode is defined as a six-week period. Multiple laboratory-positive diagnoses made more than six weeks apart are classed as separate episodes of infection.

The majority of genital chlamydia diagnoses (60%) were made in women (Table 2), which has been the pattern observed over the past decade. Genital chlamydia is an infection which predominates in young people. In 2016, 68% of all diagnoses (75% and 58% of all female and male diagnoses, respectively) were made in those aged under 25 years (Table 3). The majority of diagnoses were made among women and men aged 20-24 years. This has been a consistent finding for the past ten years (except for women in 2010, where more diagnoses were observed in those aged under 20).

In 2016, for women, the highest rates of diagnoses per 100,000 population were observed in NHS Tayside and NHS Lothian (over 600 diagnoses per 100,000 population) (Table 4). There was a similar observation for men with the highest rates in NHS Tayside and NHS Lothian (over 400 diagnoses per 100,000 population). Outside the island NHS boards, the lowest rates for men and women were observed in NHS Highland and NHS Lanarkshire. NHS Highland data are thought to reflect an under-representation of diagnoses, as Highland residents living in areas which were part of the former NHS Argyll & Clyde may have been diagnosed in, and reported from, NHS Greater Glasgow & Clyde.

For those aged under 25 years, rates of diagnoses per 100,000 population are much higher than for the overall diagnosed population. Outside the island NHS boards, among young women aged under 25, the highest rates of diagnoses per 100,000 population were observed in NHS Tayside and NHS Lothian (greater that 2400 diagnoses per 100,000 population) (Table 4 and Figure 1). Among young men, the highest rates of diagnoses were recorded in NHS Tayside, NHS Borders and NHS Lothian (over 1200 diagnoses per 100,000 population). Outside the island NHS boards, the lowest rates were observed in NHS Lanarkshire for both men and women aged under 25 years.

Lymphogranuloma venereum (LGV) infection, caused by a serovar of Chlamydia trachomatis, re-emerged during 2003/2004 when outbreaks were reported in many European cities. LGV infection occurs predominantly in men who have sex with men (MSM) and is associated with high levels of concurrent STIs, in particular HIV and with high risk sexual behaviour, including multiple anonymous partners. Since its re-emergence, over 4600 diagnoses have been reported in the UK to the end March 2016 (latest report available).2 The UK now has the largest documented outbreak of LGV among MSM in Europe.2,3 In Scotland during 2016, 45 LGV diagnoses were recorded, all of which were among men, compared to 15 in 2015, eight in 2014, 11 in 2013, 10 in 2012 and six in 2011. Provisional 2017 data indicate that the number may have returned to pre-2016 levels with 13 diagnoses recorded at the end of August 2017.


In 2016, 2363 diagnoses of gonorrhoea were reported to HPS, a similar number to that reported in 2015 (2346). This follows a 28% increase between 2014 and 2015. Since 2012, nucleic acid amplification tests (NAATs) have been in routine use across Scotland.4 During this time, there has been a concomitant increase in extragenital testing. Testing strategy has now stabilised and epidemiological trends since 2013 are more comparable than those in previous years. Furthermore, since 2015, confirmatory testing is now being performed by several testing laboratories and not exclusively by the Scottish Bacterial Sexually Transmitted Infection Reference Laboratory (SBSTIRL). As a consequence, the number of episodes reported here differ from those reported in the GASS 2016 report (HPS Weekly report, this issue). Thus, while a proportion of the increase in episodes during the past few years is due to more effective testing, it is likely that the incidence of infection has also increased.

Over the past decade, there has been annual variability in the number of episodes in each NHS board and, for some NHS boards, no clear trends in incidence are evident (Table 6, Figure 2). However, an increase in the number of episodes was noted in several NHS board areas in 2016. A continuing pattern remains of one third of episodes being diagnosed in NHS Greater Glasgow & Clyde and around one quarter being diagnosed in NHS Lothian.

In contrast to genital chlamydia, the majority of gonorrhoea diagnoses were made in men (Table 5). The male:female ratio was 2.9:1, which is lower than that observed in 2015 (4.2:1) but similar to the ratio in preceding years (3:1 male:female).

In women, infection with gonorrhoea is associated predominantly with a younger age group, with 67% of female episodes occurring in those aged under 25 years (Table 7). For men, in 2016, 41% of episodes occurred in those aged under 25 years (Table 7).

The increase in gonorrhoea among men, is considered to be due, largely, to transmission among men who have sex with men (MSM). Rectal gonorrhoea is a key marker for condomless anal intercourse. In 2016, 37% of episodes in men were diagnosed from a rectal swab positive for gonorrhoea (Table 8). The number and proportion of episodes of male rectal gonorrhoea remains high and compares with 37% and 40% recorded in 2014 and 2015, respectively.

In 2016, the highest rates of gonorrhoea infection for men (at over 160 per 100,000 population) were seen in NHS Greater Glasgow & Clyde and NHS Lothian and for women (at over 40 per 100,000 population) in NHS Lothian and NHS Grampian (Table 9).


Overall, the number of laboratory-positive diagnoses for genital chlamydial infection and gonorrhoea infection has remained similar between 2015 and 2016.

Infection among heterosexual men and women

Information about sexual orientation is not available from laboratory reports to SBSTIRL or through ECOSS. It is therefore not possible to identify whether infections in men are occurring among those who have sex with women or those who have sex with men. The analysis of STIs in women can however be used to provide an insight into heterosexual transmission.

Testing for many STIs has increased since the start of the last decade due to a combination of improvements in access to sexual health clinics, sexual health promotion activities and, improvements in test technology. Testing for chlamydia infection, which is asymptomatic in up to 80% of individuals, also increased during this time,5 initially as a result of the SIGN guideline6 recommendations which included the provision of NAAT testing platforms which enable samples to be tested for both chlamydia and gonorrhoea. It is also likely that this change in testing practice has resulted in an increase in gonorrhoea diagnoses.

Prior to 2011, annual increases in the number of chlamydia diagnoses were recorded, due in part to a combination of increased opportunistic testing,5,6 the use of more sensitive diagnostic tests,6 increased awareness through health promotion campaigns, and latterly, improvements in data collection. Between 2011 and 2015, a reverse in the number of diagnoses has been observed with an 8% decrease between 2014 and 2015 resulting in the lowest annual total recorded over the past decade. In 2016, the number of positive chlamydial diagnoses has remained similar. Over the past few years, genital chlamydia diagnoses have decreased and it is, as yet, unclear whether this reflects a true decrease in incidence or a decrease in opportunistic testing with a more targeted approach. In recent years, there has been discussion about the extent of opportunistic testing and testing of asymptomatic individuals as a result of the initial findings of the CMO Expert Advisory Group on Chlamydia trachomatis testing. HPS is unable to measure the extent of opportunistic testing with our current data collection systems, but it may be that levels of testing have decreased resulting in the lower numbers of diagnoses. Nevertheless, there is no doubt that very large numbers of people are infected, particularly those in the younger age groups. The discrepancy between the numbers of male and female chlamydial infections is almost certainly due to more women than men undergoing testing.

Trends in gonorrhoea diagnoses among women could be considered true reflections of any changes in high-risk sexual behaviour among heterosexual populations. During the past five years, the number of annual diagnoses in women has fluctuated between 450 and 600. However, in 2016, we observed over 600 episodes, a 36% increase on that reported since 2015 and the highest number for several years. The majority of gonorrhoea infections in women occur in those under 25 years of age.

The data continue to indicate that young people, in particular women, are acquiring STIs at an early age. Thus, it is essential that efforts to effect behavioural change in this group, through positive sexual health messages, are continued while encouraging individuals to undergo testing when at risk of infection and so receive appropriate treatment.

Infections among men who have sex with men (MSM)

As laboratory data contain no information on sexual orientation, rectal gonococcal infection may be used as a surrogate marker for sex between men. The incidence of rectal gonorrhoea, an indicator of condomless anal intercourse between men, accounted for 37% of male gonorrhoea diagnoses. This is similar to that reported in 2015, when 40% of male gonorrhoea diagnoses included a rectal infection. Nevertheless, it is encouraging that the incidence of rectal gonorrhoea in 2016, while still high at 650 episodes, decreased by 14% when compared to the 758 figure for 2015.

The likelihood of HIV transmission is increased in the presence of another STI, particularly rectal gonorrhoea. HPS reported a decrease in the overall number of reports of HIV among MSM, including new, first time reports in 2016.7 The data available on newly acquired or recent HIV infection (i.e. acquired within the preceding three to four months) also indicate a change: in 2015, over one third of MSM tested (35%) had evidence of a recent infection; while both the number and proportion decreased in 2016 with around one fifth (22%) of MSM recently infected. While this is encouraging and is likely to be related in part to the high levels of individuals on treatment (and therefore a reduction in overall community viral load), it is not yet clear whether this decrease in HIV diagnoses will be sustained in 2017.7 It is too early to observe an effect on HIV incidence based on the use of HIV pre-exposure prophylaxis (PrEP) which, following the SMC decision in April 2017, has been provided by the NHS in Scotland since the beginning of July. The introduction of PrEP may have an effect on sexual behaviour, and thus on STI incidence. Plans are being put in place to monitor the impact of PrEP use.

There are a number of additional sexual health concerns in this population; the annual incidence of infectious syphilis among MSM having increased in recent years and diagnoses in men overall having reached the highest level recorded for over 60 years.8 The sexual transmission of Shigella infection is also a concern, and has been associated with a high number of sexual partners, increased rates of HIV and chemsex.9,10 In recent years, along with the rest of the UK, Scotland has seen an increase in rectal STIs such as Lymphogranuloma venereum (LGV). Since June 2016, there has been an outbreak of hepatitis A throughout Europe11 including in England where there have been almost 300 diagnoses with at least 74% of these among MSM at April 2017.12 However, there is no evidence to suggest that hepatitis A is being widely transmitted among MSM in Scotland. This may be due, in part, to levels of immunity as a result of continued efforts to vaccinate MSM against hepatitis B, which has, in many clinics, involved the use of the combined hepatitis A/hepatitis B vaccine. BASHH guidance changed in 2017 to advise that all MSM attending sexual and reproductive health services should receive hepatitis A vaccine.13

In summary, information from the infection data (particularly the high level of rectal gonorrhoea) suggest that condomless sexual intercourse and risk of STI infection among MSM continue. There are ongoing challenges for the control and prevention of STIs in MSM.


  1. Health Protection Scotland. ECOSS (The Electronic Communication of Surveillance in Scotland). Available from: (accessed 21 September 2017).
  2. Public Health England. Lymphogranuloma venereum (LGV): guidance, data and analysis. Available from: (accessed 21 September 2017).
  3. Childs T, Simms I, Alexander S et al. Rapid increase in lymphogranuloma venereum in men who have sex with men, United Kingdom, 2003 to September 2015. Euro Surveill. 2015;20(48):pii=30076. Available from: (accessed 21 September 2017).
  4. Scottish Microbiology Forum, British Association of Sexual Health and HIV, Health Protection Scotland. Guidance on the use of molecular testing for Neisseria gonorrhoeae in diagnostic laboratories 2011. Available from: (accessed 21 September 2017).
  5. Health Protection Scotland. Key Clinical Indicators for Sexual Health Report 2010. Available from: (accessed 21 Septemmber 2017).
  6. Scottish Intercollegiate Guidelines Network. Management of genital Chlamydia trachomatis infection. No.109. Edinburgh: SIGN, March 2009. Available from: (accessed September 2017).
  7. Health Protection Scotland. ANSWER HIV infection and AIDS: quarterly report to 30 June 2017. HPS Weekly Report 2017; 51(36): 313-319. Available from: (accessed 21 September 2017).
  8. Health Protection Scotland. Syphilis in Scotland 2016: update. HPS Weekly Report 2017:51(33):278-287. Available from: 9accessed 21 September 2017).
  9. Simms I, Field N, Jenkins C et al. Rapid communication: Intensified shigellosis epidemic associated with sexual transmission in MSM - Shigella flexneri and S. sonnei in England, 2004 to end of February 2015. Euro surveill. 2015;20(15):pii=21097. Available from: (accessed 21 September 2017).
  10. Gilbart VL, Simms I, Jenkins C et al. Sex, drugs and smart phone applications: findings from semi-structured interviews with MSM diagnosed with Shigella flexneri 3a in England and Wales. Sexually Transmitted Infections 2015;91(8):598-602. Available from: (accessed 21 September 2017).
  11. European Centre for Disease Control and Prevention. Rapid risk assessment: Hepatitis A outbreak in the EU/EEA mostly affecting me who have sex with men, 3rd update, 28 June 2017. Available from: (accessed 21 September 2017).
  12. Public Health England. Hepatitis A outbreak in England under investigation. Health Protection Report. 2017;11(17). Available from: (accessed 21 September 2017).
  13. Public Health England. Hepatitis A vaccination in adults – temporary recommendations. Available from: (accessed 21 September 2017).


HPS wishes to thank consultant microbiologists, consultant virologists and their staff who supply data to the SBSTIRL and to HPS.

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Author(s): Prepared by: KMA Trayner, LA Wallace, J Shepherd, K Templeton, DJ Goldberg Vol: 51 No: 38 Year: 2017 Page:


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