Background:
Increases in early syphilis cases reported in Baltimore City, Maryland imply that a new epidemic may be emerging among men who have sex with men (MSM) and adolescent females. Such findings have raised questions about what additional prevention and control strategies are needed and whether the recent outbreaks among these populations are linked.

Objective:
To explore whether heterosexual bridging among syphilis infected MSM may be contributing to increased infection rates among adolescent females in Baltimore.

Method:
Interview data for primary, secondary, and early latent syphilis cases from January 2001-July 2005 were linked with their corresponding field records for named contacts to assess the prevalence of male bisexual activity and risk profiles of potential male bisexual bridgers and their female sex partners.

Result:
None of the syphilis infected women reported having known heterosexual relations with a bisexual man. However, 3.9% and 11.0% of the male sex partners of syphilis infected adolescent females and women greater than or equal to 25, respectively, self-reported as an MSM and/or named male sex partners. Likewise, 10% of syphilis positive MSM named female sex partners with 3.4% reporting a 12-24 year old female sex partner. Three percent of syphilis positive males who did not self-identify as MSM named both male and female sex partners with at least 1.5% reporting a 12-24 year old female sex partner.

Conclusion:
Sexual network links exist between syphilis infected MSM and heterosexual women but the extent of bisexual behavior among men is not detectable by self-identification and disclosure to female sex partners.

Implications:
More nuanced categorizations of MSM based not only on self-identification but also on who respondents name as sex partners would aid in the identification of potential bisexual bridgers for whom prevention activities could be targeted.