Syphilis Positivity Among Men Who Have Sex With Men With Direct, Indirect, and No Linkage to Female Sex Partners: Exploring the Potential for Sex Network Bridging in Baltimore City, MD.

BACKGROUND

Syphilis epidemics among women and men who have sex with men (MSM) may be connected, but these connections are poorly understood. Using egocentric network data from a US urban MSM cohort, we examined sociodemographics, behaviors, and syphilis positivity among MSM with (1) direct (MSM who report sex with women, MSMW); (2) indirect (MSM who only report male partners, some of whom are MSMW, MSMO/W); and (3) no (MSM who only report male partners and whose partners only have sex with men, MSMO/O) connection to women.

METHODS

Sexually active MSM aged 18 to 45 years were administered behavioral and network interviews (recall period: 3 months) and syphilis/HIV testing. Syphilis positivity was defined as rapid plasma reagin titer ≥1:8. Modified Poisson regression was used to test for differences across groups.

RESULTS

Among 385 MSM, 14.5% were MSMW and 22.3% were MSMO/W. MSMW and MSMO/W were significantly more likely than MSMO/O to report sex behaviors associated with increased syphilis acquisition/transmission risk, including ≥2 sex partners (MSMW: adjusted prevalence ratio [aPR], 1.28 [0.98-1.68]; MSMO/W: aPR, 1.35 [1.09-1.69]) and concurrent sex partners (MSMW: aPR, 1.50 [1.17-1.92]; MSMO/W: aPR, 1.39 [1.11-1.74]), and for MSMW only, transactional sex (aPR, 2.07 [1.11-3.88]). Syphilis positivity was 16.4% and was lower among MSMW (9.4%) and MSMO/W (14.1%) than MSMO/O (18.5%), but differences were not significant.

CONCLUSIONS

There may be considerable connectivity between MSM and female sex partners that could facilitate syphilis transmission, and behaviors that increase acquisition/transmission risk among MSMW and MSMO/W may be distinct from MSMO/O. Future work should focus on examining the context and temporal patterns of sex partnerships among MSMW and MSMO/W.