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Eurosurveillance, Volume 9, Issue 12, 01 December 2004
Surveillance report
Syphilis surveillance and epidemiology in the United Kingdom

Citation style for this article: Righarts AA, Simms I, Wallace L, Solomou M, Fenton KA. Syphilis surveillance and epidemiology in the United Kingdom. Euro Surveill. 2004;9(12):pii=497. Available online: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=497

 

A A Righarts1, I Simms1, L Wallace2, M Solomou1, KA Fenton1,3


1. HIV and STI Department, Health Protection Agency, Centre for Infections, London, United Kingdom
2. Health Protection Scotland, Clifton House, Clifton Place, Glasgow, United Kingdom
3. Centre for Sexual Health and HIV Research, Department of Primary Care and Population Sciences, Royal Free and University College Medical School, Mortimer Market Centre, London, United Kingdom

 


The aim of this article is to describe trends in infectious syphilis in the UK, and specifically the epidemiology of the London syphilis outbreak, the largest in the UK to date.
Analysis of routine surveillance data from genitourinary medicine (GUM) clinics was performed as well as data collection through enhanced surveillance systems.
There have been substantial increases in diagnoses of infectious syphilis between 1998 and 2003, with a 25-fold increase seen in men who have sex with men (MSM) (from 43 to 1028 diagnoses); 6-fold (138 to 860) in heterosexual men and 3-fold (112 to 338) in women. The national rise in syphilis was driven by a series of local outbreaks, the first of which occurred in 1997. To date, 1910 cases have been reported in the London outbreak, first detected in April 2001. High rates of HIV co-infection were seen among MSM, with MSM likely to be of white ethnicity and born in the UK. In contrast, heterosexuals were more likely to be of black ethnicity and born outside the UK. Most syphilis infections were acquired in London.
MSM bear the brunt of the national resurgence in infectious syphilis. Substantial rises in male heterosexual cases has resulted in a divergence between male heterosexual and female cases, which now requires further investigation.

 
Introduction

Against a backdrop of increasing diagnoses of acute STIs and HIV prevalence in the United Kingdom (UK), diagnoses of infectious syphilis have risen dramatically since 1998 [1]. This resurgence has been facilitated by a number of outbreaks throughout the UK. The outbreaks have occurred mainly in men who have sex with men (MSM), and, more recently, in heterosexual men and women [2].

Comprehensive, existing routine STI surveillance systems from genitourinary medicine (GUM) clinics are unable to provide timely data in the context of a rapidly evolving epidemic; data often taking a minimum of 6 months to collate. Therefore, enhanced syphilis surveillance systems were developed and implemented in order to improve clinical case reporting. Similar enhanced surveillance systems now operate throughout the UK [2].

The aim of this article is to describe the epidemiology of infectious syphilis in the UK in 2003. We also explore key features of the London infectious syphilis outbreak.

Methods

Routine surveillance of syphilis

Routine surveillance data on STIs in the UK are derived from diagnoses made in GUM clinics reported on the KC60 form (ISD(D)5 form in Scotland). GUM clinics have had a statutory obligation to record data since 1917 [1]. Reliable trend data on primary, secondary and early latent syphilis diagnosed in GUM clinics extend back to 1931.

GUM clinics in England, Wales and Northern Ireland return quarterly data to the Health Protection Agency (HPA) on total episodes by condition, sex and for selected conditions, by sexual orientation and/or age group. In contrast, Scottish data are episode based and returned to the Information and Statistics Division (now Information Services) in Scotland. Reported data includes primary and secondary syphilis, early latent syphilis, other acquired syphilis (e.g. cardiovascular and neurosyphilis), congenital syphilis, and epidemiological treatment of suspected syphilis [1].

Routine GUM data returns are often delayed; for example, complete KC60 data for 2003 is only available in June 2004. Similarly, difficulties extracting Scottish ISD(D)5 data have resulted in incomplete or no data being available currently for 2001, 2002 and 2003.

Data on syphilis and other STIs diagnosed at GUM clinics are made publicly available in a series of annual reports, on the HPA website (UK data), and both the Information and Statistics Division (ISD) and Scottish Centre for Infection and Environmental Health (now Health Protection Scotland, HPS) websites (Scottish data only) [(3-5].

Enhanced surveillance initiatives

In response to the resurgence in syphilis since the late 1990s, a number of enhanced surveillance initiatives were implemented. These initiatives were designed to provide prompt demographic, behavioural and clinical data in order to inform health planning and intervention strategies. The first enhanced surveillance programme commenced in Manchester in 1999 and was extended to cover the North West region in 2003. The London Enhanced Syphilis Surveillance programme was established in 2001. This was subsequently extended to the rest of England and Wales in 2003 [2]. A similar system, based on the London programme, was established in Scotland in late 2002; data were collected retrospectively to 2001 [6]. Table 1* shows the data collected for the London Enhanced Syphilis Surveillance Programme. Other initiatives collect similar data.


Epidemiological features of the London outbreak were analysed with STATA v8.0, and chi squared tests were used to ascertain P-values for differences in proportions.

Results

Overview
Diagnoses in infectious (primary, secondary and early latent) syphilis declined rapidly during the 1980s with the advent of HIV/AIDS and the subsequent introduction of HIV prevention strategies aimed at sexual behaviour modification. A relatively low level of diagnoses was maintained through most of the 1990s; between 1995 and 1998 an average of only 300 diagnoses were seen annually throughout the UK. The first outbreak of infectious syphilis occurred in Bristol in 1997 [2]. This was followed by outbreaks in the cities of Manchester [7], Brighton, Peterborough, London, Newcastle upon Tyne, Glasgow, Edinburgh, Walsall and the regions of south Wales and Northern Ireland [FIGURE 1].

Routine surveillance of syphilis in the UK
GUM diagnoses of infectious syphilis are now at their highest levels in the UK since 1984. A total of 2233 diagnoses were made in GUM clinics during 2003; 1028 in men who have sex with men (MSM), 860 in heterosexual men, and 338 in women. Since 1998, there has been a 25-fold increase in MSM (from 43 to 1028 diagnoses). Rises of a lower magnitude of 6-fold (138 to 860) and 3-fold (112 to 338) were seen in heterosexual men and women respectively (FIGURE 2). There is a continuing divergence in male heterosexual cases and female cases since 2000. In 2000, the ratio of heterosexual male to female cases was 1.2:1, in 2003 it was 2.5:1.

Increases in infectious syphilis were mirrored in other forms of syphilis in England, Wales, and Northern Ireland (Scottish ISD(D)5 data not available in 2003). Other acquired syphilis rose by 108% (76 to 158) between 1998 and 2003 in MSM, by 55% (564 to 874) in heterosexual men and 117% (376 to 817) in women. This was accompanied by small numbers of congenital syphilis cases. There were also increases in the epidemiological treatment of suspected syphilis from 0 cases in 1998 to 147 cases in 2003 in MSM, from 20 to 109 case in heterosexual men and 36 to 67 cases in women.

The distribution of regional patterns of syphilis diagnoses largely reflects the impact of outbreaks. In 2003, London accounted for 42% of diagnoses in MSM, 42% in heterosexual men and 52% in women. The North West (18%, 12% and 8% in MSM, heterosexual men and women respectively) and South East regions of England (12%, 10% and 11% in MSM, heterosexual men and women respectively) also accounted for a high proportion of diagnoses.

Age group data are currently only available for primary and secondary syphilis in England Wales and Northern Ireland. Unlike other STIs, relatively few diagnoses were made in younger age groups. The highest rates of syphilis were seen in men aged 25 to 34 years (13.5 per 100,000) and 35 to 44 years (11.7 per 100,000). In women the highest rates were seen in those aged 20 to 24 years (2.5 per 100,000) and 25 to 34 years (1.9 per 100,000) (8).

Enhanced syphilis surveillance in London
The London outbreak is the largest reported in the UK to date with 1910 diagnoses of infectious syphilis reported between April 2001 and end September 2004. The characteristics of the outbreak were similar to those seen throughout the rest of the UK, other areas of western Europe and the United States [2]. Infections are geographically clustered, and associated with high rates of partner change in core risk groups, and concurrent HIV infection.

Two epidemics are evident in London: one among MSM (1276 cases) and one among heterosexual men (383 cases) and women (237 cases) (FIGURE 3). As seen in the routine surveillance data there is a disparity between heterosexual male and female diagnoses.

In both MSM and heterosexuals the majority of cases attended GUM clinics with symptoms (61% and 53% respectively) or for routine asymptomatic screening (27% and 20% respectively). There were significant differences in the other characteristics of MSM and heterosexuals diagnosed with infectious syphilis [TABLE 2]. MSM with infectious syphilis were older than heterosexuals, more likely to be HIV positive and more likely to present with secondary syphilis [TABLE 3]. Sixty-five per cent of MSM were born in the UK and 89% were of white ethnicity. In contrast, only 46% of heterosexuals were born in the UK and 44% were of white ethnicity.

Most infections were acquired in London: 85% in MSM and 76% in heterosexuals. MSM were significantly less likely to acquire their infection abroad.

In general, MSM reported higher prevalence of sexual risk behaviour. They reported a higher number of sex partners (a median of three in the last three months compared with one in heterosexuals); and a higher proportion used social venues/sexual networks for acquiring new partners (36% versus 7% in heterosexuals). Links with the commercial sex industry were evident in heterosexuals. Thirteen percent of those diagnosed with infectious syphilis were either commercial sex workers (CSW) or CSW clients. Only three percent of MSM had links with CSW.

Syphilis in heterosexuals
When comparing syphilis cases in heterosexual men and women, men were significantly older than women and more likely to present with primary syphilis [TABLE 3].Two thirds of heterosexual men attended due to symptoms, compared with just 30% of women. A further 29% of women attended due to other reasons (e.g. a positive antenatal screen). A higher proportion of heterosexual men reported using venues/sexual networks for acquiring new partners (10% versus 3% in women), and oral sex being the likely mode of transmission (11% versus 4% in women). Heterosexual men also reported higher numbers of partners: a median of two in the previous three months versus a median of one in women.

A common feature of syphilis outbreaks in England is the high proportion of concurrent HIV infection in MSM diagnosed with infectious syphilis [2]. In London, 53% of MSM were HIV positive; this has remained fairly stable throughout the outbreak. HIV co-infection in MSM with syphilis was strongly associated with age group, stage of syphilis infection, reason for attending, and use of sexual networks [TABLE 4]. Forty-one per cent of those with concurrent HIV infection frequented sexual venues compared with 31% in those who were HIV negative. There was no discernable difference between HIV positive and negative MSM in terms of where the infection was acquired, country of birth, ethnicity, oral sex as mode of acquisition, CSW links or numbers of sexual contacts.


Discussion

Routine surveillance data confirm continuing increases in syphilis diagnoses during 2003 in MSM and heterosexual men, and to a lesser extent in women. The balance of the epidemic remains in MSM, despite data up to end September 2004 which suggests that the London epidemic in MSM is plateauing. However, this is not consistent throughout the UK, and preliminary 2004 data from enhanced surveillance in Scotland indicate continuing increases in MSM in Glasgow and Edinburgh.

Nationally, our surveillance data confirm a continued divergence between diagnoses in heterosexual men and women; a trend also observed in London during 2002 and 2003 [FIGURE 2]. The excess male cases may have resulted from the association between heterosexual outbreaks and the commercial sex industry. The divergence may also be due to differences in clinical presentation and health seeking behaviour [TABLE 3]. This conflicts with London enhanced surveillance [FIGURE 3], where some of the convergence may be due to reporting bias.

Key features of syphilis epidemiology in the UK include the geographical isolation of outbreaks, especially amongst MSM where there was little imported infection; localisation amongst CSW and their clients with a steady increase in heterosexual transmission, and the high proportion of concurrent HIV infection in MSM.

The potential impact of syphilis infection on HIV transmission is concerning, and further studies examining the impact on HIV incidence are now needed. Also worrying is the increased risk of congenital syphilis cases which may accompany the rise in heterosexual transmission. Whilst there have been ad hoc reports of congenitally acquired syphilis associated with heterosexual outbreaks, there is a conspicuous lack of surveillance activity in this area which needs to be tackled urgently.

Acknowledgements

We would like to thank the staff of all the GUM clinics that contributed to the enhanced surveillance initiative. We would also like to thank Dr. Chalmers and staff at Information Services, NHS National Services Scotland for providing ISD(D)5 data, Dr. Thomas at CDSC, National Public Health Service Wales, Dr. Gorton at HPA North East, Mr. Ashton at HPA North West, Dr. Fox at CDSC Northern Ireland and Dr Joseph at The Manor Hospital from providing data on local outbreaks.
 
*Editorial note-erratum:Table 1 has been replaced by reference 1, with the authors' agreement; the Table 'Data collected in the London enhanced syphilis surveillance programme' was omitted and is now included, named Table 1; therefore all tables have been renamed accordingly [Eurosurveillance editorial office, 17 January 2005]
Tables 2, 3 and 4 have been corrected by the authors [Eurosurveillance editorial office, 24 January 2005]


References

1. Sexually transmitted infections in the United Kingdom: new episodes seen at genitourinary medicine clinics, 1999-2001. A joint publication between the PHLS (England, Wales and Northern Ireland), DHSS&PS (Northern Ireland) and the Scottish ISD(D)5 collaborative group (ISD, SCIEH, and MSSVD)
2. Simms I, Fenton KA, Ashton M, Turner KME et al. The re-emergence of syphilis in the UK: the new epidemic phases. Sex Transm Inf. 2004, in press
3. HPA. Epidemiological data – syphilis [accessed 31 July 2004]. Available at:
http://www.hpa.org.uk/infections/topics_az/hiv_and_sti/sti_syphilis/syhpilis.htm
4. GUM clinic activity, Scotland [accessed 31 July 2004]. Available at: http://www.isdscotland.org/isd
5. Health Protection Scotland (formerly the Scottish Centre for Infection and Environmental Health, SCIEH). [accessed 21 December 2004]. Available at: http://www.hps.scot.nhs.uk/
6. Wallace L. Syphilis is Scotland 2003. SCIEH Weekly Report. 2004; 38: 38-9 available at: http://www.show.scot.nhs.uk/scieh/PDF/pdf2004/0407.pdf
7. Ashton M, Sopwith W, Clark P, McKelvey D, Lighton L, Mandal D. An outbreak no longer: factors contributing to the return of syphilis in Greater Manchester. Sex Transm Infect. 2003 79(4):291-3
8. CDSC. Trends in infectious syphilis; update on national data to 2003 and current epidemiological data from the London outbreak. Commun Dis CDR Wkly [serial online]. 2004 [cited 31 July 2004]

 

 



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