Subsequent HIV Diagnosis Risk After Syphilis in a Southern Black Population

Southern non-Hispanic black persons are disproportionately represented in the HIV epidemic. Those previously diagnosed as having syphilis are at significant risk to become HIV infected within 36 months. Effective prevention strategies such as preexposure prophylaxis should be offered to those at highest risk to maximize prevention efforts.

HIV-negative persons diagnosed as having primary or secondary (P&S) syphilis during 1998-2014 were matched with incident HIV cases diagnosed during 1998-2016 in Shelby County Tennessee. Person-year HIV incidence rate, Kaplan-Meier survival estimates, and Cox proportional regression model analyses were performed to explore predicting risk factors and quantifying risk factors associated with HIV-free survival time frames.

Among 2032 HIV-negative non-Hispanic black Shelby County residents diagnosed as having P&S syphilis, 139 (6.8%) were subsequently diagnosed as having HIV infection. Men who have sex with men (MSM) experienced the highest incidence of HIV diagnosis rate (4.98 per 100 person-years, 95% confidence interval, 4.76-5.2). Being male, MSM, younger than 30 years, or coinfected with gonorrhea increased risk of HIV acquisition 2.32, 11.80, 1.67, and 2.44 times, respectively, compared with being female, heterosexual men, 30+ years old, or not infected with other sexually transmitted infections.

Among our population diagnosed as having P&S syphilis, 1 in 6 MSM and 1 in 16 persons coinfected with gonorrhea were subsequently diagnosed as having HIV during 36 months of follow-up. These findings have implications for HIV screening and recruitment as priority preexposure prophylaxis candidates.