Investigation of a cluster of syphilis among heterosexuals in an English town

INTRODUCTION

The east of England region has one of the lowest rates (1.7 per 100,000) of syphilis in the country. ¹ Diagnoses in England are predominantly in men, particularly men who have sex with men (MSM). In 2009, 59 cases were diagnosed in the east of England region, with 83% in men, of whom 51% were in MSM. ¹ This report describes a syphilis outbreak among young heterosexuals.

CASE REPORT

In June 2010, the Ipswich genitourinary (GU) medicine clinic informed the Health Protection Agency (HPA) that they had diagnosed an unusually high number of cases of infectious syphilis since the beginning of the year. In the six months since 1 January 2010, 12 cases had been diagnosed in comparison with less than five cases in both 2008 and 2009. This was clearly in excess of the number of expected cases and a preliminary outbreak investigation team was formed in line with the HPA guidelines. ²

Two cases were excluded as they were found to be older cases with known latent syphilis. Of the remaining 10 cases, four were in MSM (3 co-infected with HIV) and all had a plausible route of infection through casual sexual contact. These were a clearly distinguished group from the remaining heterosexual cases and there was found to be no link between the two groups.

Of the six heterosexual cases, one female case was most likely to have contracted the infection in London and had no contact or connection with the remaining five heterosexual cases. This left a potential network of five cases (3 primary and 2 early latent).

Three cases were in men and two in women. One of the two women was identified through antenatal screening. All were young adults aged less than 30 years. None of the cases had been diagnosed as HIV-positive. Three out of the five cases were symptomatic.

A network of four confirmed cases was identified. The first case was diagnosed at the end of March and the fourth at the beginning of April. The last case (diagnosed in mid-June) had no known connection with the first four cases. No further linked cases have since been identified.

Control measures included raising awareness for syphilis in local networks and encouraging testing. Information on the symptoms of syphilis infection was disseminated via colleges, young patient clinics, family planning clinics and through National Chlamydia Screening Programme nurses to increase awareness in the target age group. Awareness among health-care professionals was increased through the General Practice (GP) bulletin and through the monthly newsletter circulated by Suffolk Integrated Healthcare to staff at Suffolk Integrated Services. Lastly, midwives identified cases that required repeat syphilis serology.

DISCUSSION

We have confirmed the experience of others that, in the face of an apparent outbreak, clinicians locally must explore the nature and parameters of the cluster and engage a mixture of control methods to interrupt infection spread by optimizing case-finding and by prompt treatment, and by appropriate outreach initiatives. ^3,4 The integrated service in Suffolk helped to involve a wide range of practitioners in the investigation.

The high proportion of linked cases in this heterosexual outbreak shows greater success with contact tracing for this population than for MSM, who more frequently name casual untraceable partners from outside the region or abroad, and are generally less receptive to provider referral. ^3,5 It was important to ensure that effective partner notification measures were implemented to control the spread of this infection and the GU medicine clinic health adviser carried out multiple interview sessions to uncover any potential links.

The occurrence of an outbreak among young heterosexuals points to the importance of behavioural intervention as a key component of health promotion. ⁶ Awareness of syphilis needs to be raised, safer sex should be promoted together with a reduced number of sexual partners and people at risk should be encouraged to attend clinical services for regular screening.