Background:
Between 2004 and 2005 the total number of primary and secondary (P&S) syphilis cases in Chicago, IL increased by 41% (from 297 cases in 2004 to 418 cases in 2005). Increases occurred mostly among men who have sex with men (MSM).

Objective:
To characterize persons who were diagnosed with multiple episodes of P&S syphilis between January 2004 and December 2006.

Method:
Syphilis surveillance data were analyzed using SAS version 9.1. We defined “Repeaters” as having two or more episode of P&S syphilis during the study period and “Non-Repeaters” as having a single episode of P&S syphilis.

Result:
Between 2004 and 2006, 998 cases of P&S syphilis were reported to the Chicago Department of Public Health (CDPH). The majority, 96.5%(930) persons were Non-repeaters. Of the 34 (3.5%) persons with repeat P&S syphilis infections the median time between episodes was 13.3 months (range 8-34 months). Most of repeaters (91.2%) were MSM. Most Repeaters were white (52.9%); 32.4% were black and 14.7% were Hispanic. Median age was 36 (range 23-54). At initial syphilis diagnosis 67.6% of Repeaters were HIV-positive compared to 37.5% of Non-Repeaters (OR=3.48, 95% CI 1.68-7.23). The majority (96.8%) MSM-Repeaters reported having sex with anonymous partners versus 63.5% of MSM-Non-Repeaters (OR=17.28, 95% CI 2.34-127.66). Among MSM-Repeaters, 45.2% met sex partners via the Internet and 52% met partners in bathhouses, compared to 28.6% and 22.4% of MSM-Non-Repeaters respectively.

Conclusion:
MSM were more likely than non-MSM to be diagnosed with repeat syphilis infections. High risk behaviors among MSM were associated with multiple episodes of syphilis. The potential for HIV transmission is increased by high HIV co-infection rates among MSM-Repeaters.

Implications:
Interventions should be enhanced among MSM engaged in high risk behaviors to prevent re-infection with syphilis and HIV transmission.