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Background: The velocity of STI spread depends in part on the structure of sexual networks. Co-epidemics of HIV and syphilis have persisted in NC since 2001 among young Black men who have sex with men (MSM). During 2008-2009, syphilis incidence in NC increased from 5.5 cases/100,000 person-years to 10.0/100,000. County “X” accounted for 25% of all cases, corresponding to an incidence of 57/100,000; the outbreak involved MSM, bisexual men, heterosexual men, and women.
Objectives: Using sexual network data, we sought to determine if MSMW bridged MSMs and women, thereby exacerbating syphilis transmission among heterosexuals.
Methods: We abstracted data collected as part of routine contact tracing and partner notification activities for all new diagnoses of syphilis reported to the public health department in County “X”. We also collected it for Black men ages 15-30 newly diagnosed with HIV or syphilis in County “X” and nearby counties. Social and all sexual partnerships are documented, permitting network analysis and visualization.
Results: Of 4670 people documented 11%, 14%, and 7% were syphilis, HIV, or co-infected respectively. Of the 3667 sexual partnerships, 114 involved women and MSM and 7% of women were infected with syphilis (n=2), HIV (n=3), or both (n=3). Five women had sex with an infected MSM. The women were in peripheral network positions that would impede onward transmission.
Conclusions: The few partnerships between MSM and women suggest that bisexual bridging does not seem to be a large contributor to the resurgence of syphilis among heterosexuals.
Implications for Programs, Policy, and Research: The launch of the Syphilis Elimination Program in 1999 in NC lead to a historical low of 1.8/100,000 incident syphilis cases in 2003, but was scaled back thereafter due to budgetary shortfalls. Reinstating the program and research to elucidate the growth of syphilis among heterosexuals is necessary to curb further transmission.