Reinfections during the Florida syphilis epidemic, 2000-2008.

BACKGROUND: The last 3 syphilis epidemics in the United States peaked after 5 to 6 years, but rates have now increased for 8 years. We questioned whether persons with multiple syphilis diagnoses (repeaters) are fueling the epidemic.
METHODS: The Florida Department of Health database of all syphilis cases reported between 2000 and 2008 was used to examine demographics and disease presentation of repeaters and nonrepeaters using bivariate and multivariate analyses.
RESULTS: Of 26,070 persons diagnosed with syphilis, 643 (2.5%) were repeaters (range, 2-5 diagnoses): 82 women, 444 men who have sex with men (MSM), and 117 men identified as either heterosexual (n = 43) or unknown sexual orientation (n = 74). The mean time between first and second diagnosis was approximately 3 years. Median titer increase among those with a second diagnosis of early latent was 32-fold. In multivariate analysis, compared with nonrepeaters, repeaters were more likely to be MSM (odds ratio [OR], 5.3), human immunodeficiency virus (HIV)-infected (OR, 2.0), white (OR, 1.5), ages 35 to 39 (OR, 1.8), and to live in Miami-Dade or Broward Counties (OR, 1.7). Overall, the stage at diagnosis was similar for repeaters, whether it was their initial or subsequent diagnosis. However, HIV-infected MSM were more likely to be diagnosed with early latent at second diagnosis compared with initial diagnosis (P ≤ 0.01).
CONCLUSIONS: Most syphilis diagnosed in the current Florida epidemic is among persons infected for the first time. Repeaters are mainly MSM who present with symptoms or large increases in titers. HIV-infected MSM may have higher rates of early asymptomatic disease because of more frequent screening. These are likely to be true new infections.