Evidence of heterosexual bridging among syphilis-positive men who have sex with men

Objective: To explore whether heterosexual bridging among syphilis-positive men who have sex with men (MSM) contributes to increased infection rates among adolescent women in Baltimore City, Maryland. Methods: Interview data for patients with primary, secondary and early-latent syphilis from January 2001 to July 2005 were linked with their corresponding field records for named exposed contacts to assess prevalence of male bisexual activity and risk profiles of potential male bisexual bridgers and their female sex partners. Results: None of the women with syphilis reported having known heterosexual relationships with a bisexual man. However, 3.9% and 11.0% of the male sex partners of adolescent females and women aged >25 years with syphilis, respectively, self-reported as MSM or named male sex partners. Likewise, 10.3% of syphilis-positive MSM named female sex partners and 3.0% of syphilis-positive men who did not self-identify as MSM named both male and female sex partners. Conclusions: Sexual network links exist between syphilis-positive MSM and heterosexual women, but the extent of bisexual behaviour among men is not detectable by self-identification and disclosure to female sex partners.