Background
Syphilis is a sexually transmitted infection (STI) caused by the bacterium Treponema pallidum and is notifiable under the Infectious Disease Regulations 1981. Up to 2013, HPSC was notified of all cases of syphilis in Ireland, regardless of stage of infection.
A change in the case definition and laboratory notification criteria for syphilis was made in January 2014, whereby only laboratory diagnosed early infectious syphilis (EIS) cases, and re-infections of syphilis, became notifiable. The term early syphilis relates to primary, secondary and early latent syphilis. These laboratory diagnosed notifications are then reviewed clinically, staged, and subsequently deactivated in the CIDR system by Public Health if they are not EIS cases as determined by clinical assessment.
In 2014, there was an increase in the rate of EIS, but this increase was more marked in 2015, and occurred particularly among MSM (men who have sex with men). Having timely accurate information on EIS is an essential component of being able to respond adequately to the increases seen.
A review of syphilis cases notified to HSE East (Dublin, Kildare and Wicklow) in Quarter one of 2014 was undertaken as it was originally anticipated that, with the new laboratory criteria for notification, a relatively small proportion of events would be deactivated following clinical review, but this was not the case. In Q1 2014, 47% of laboratory notifications were later deactivated. This review found that it was possible to refine the laboratory criteria for notifying new cases of syphilis, which would lead to fewer cases being reported, and of these, the likelihood of them being deactivated subsequently would be much lower.
The staging of syphilis cases, Public Health follow-up and CIDR deactivation is time consuming for both STI clinics and Public Health Departments with a time lag of up to 6 months following initial notification. Simplifying the surveillance provides more timely information which is essential to inform the response to the current increase in syphilis amongst MSM.
Updated Laboratory Criteria
From 1st July, 2016, updated laboratory criteria for notification of syphilis cases to Public Health will apply.
- Laboratories are requested to notify any new case that fits one or more of the criteria set out in Table 1, and any syphilis re-infections. Laboratories are to use their own internal criteria for notification of re-infections.
Table 1: Laboratory criteria for notification of new cases* of syphilis
Criteria 1 | Criteria 2 | Criteria 3 | Criteria 4 |
T. pallidum EIA positive AND TPPA/TPHA positive AND RPR positive at titre of >= 1:16 | T. pallidum EIA positive AND TPPA/TPHA positive AND T. pallidum EIA IgM positive | Demonstration of treponemes in lesions, exudates or tissues from clinically appropriate sites by dark ground microscopy | Demonstration of treponemes in lesions, exudates or tissue from clinically appropriate sites by PCR |
*A new case is the first time a patient is tested in the laboratory
- Public Health to seek stage of infection from clinicians on the laboratory-reported EIS cases as per the amended criteria. The new amended enhanced surveillance form (ESF) that clarifies the stage of infection requirements is available here.
- Cases which are deemed clinically to be EIS, but do not meet the revised laboratory criteria, should be notified to Public Health by clinicians.
- National surveillance reports will report on notified EIS cases, which will include all laboratory cases notified as per the new criteria (including those pending stage of infection information).
These changes will not impact on laboratory diagnostic practices, the flow of clinical information between laboratories and clinicians, or the clinical management of patients. The changes are only for the purpose of surveillance.
The updated case definition is available on the HPSC website
Latest syphilis data available on the HPSC website:
Weekly HIV and STI reports
Provisional STI data for 2015
Gillian Cullen and Derval Igoe, HPSC
