Syphilis Serologic Prevalence Monitoring Among STD Clinic Clients: Correlation With Reported Syphilis Incidence, San Diego, CA, 1985–2004

Abstract

To describe the serologic test for syphilis (STS) prevalence among STD clinic clients, determine the correlation between STS prevalence trends and reported community-diagnosed primary and secondary (P&S) case incidence, and evaluate the usefulness of STS prevalence monitoring as a component of syphilis surveillance. During the period 1985-2004, 21,4336 STS were done among STD clinic clients and a variety of STS prevalence measures were evaluated. From 1985-1991, 10.2% of STS were positive, which declined to 5.6% during 1992-2004. Overall, STS positivity (>or=1:8) and male positivity (>or=1:8) trends were correlated with reported community-diagnosed P&S case incidence and case incidence in men (r = 0.58 and r = 0.81, respectively). Male STS positivity (>or=1:8) began increasing in 2001, 1 year before the increase in syphilis incidence in men, which began in the latter half of 2002 and occurred mostly among men who have sex with men. In a syphilis outbreak in men who have sex with men, STS prevalence (>or=1:8) among male STD clinic clients was a useful measure of syphilis case incidence trends and may provide an early warning for a subsequent increase in community-diagnosed case incidence.