A proposal for changes to the European Union syphilis surveillance case definition using evidence from evaluations in Ireland

Syphilis remains a disease of public health importance, with considerable health effects if not treated. Concurrent infection with syphilis and untreated HIV facilitates HIV transmission. The incidence of syphilis in Europe has been increasing, particularly among men who have sex with men (MSM) and in MSM with HIV. However, there is heterogeneity among countries in the case definition used for syphilis and in reported syphilis notification rates. In Ireland, we have undertaken a number of refinements of the national syphilis surveillance system since 2014, including refinement of the laboratory thresholds for notification (rapid plasma reagin 1:16 and/or positive IgM). This article outlines the steps taken and some of the challenges we faced. Our current case definition now accurately reflects the epidemiology of syphilis in Ireland and our current surveillance provides timely information for action, while not reducing the sensitivity of the system too much. For countries where surveillance is driven mainly by laboratory reporting and where obtaining clinical details is challenging, these thresholds for notification may be a pragmatic solution.