State-Specific Rates of Primary and Secondary Syphilis Among Men Who Have Sex with Men — United States, 2015

Abstract

In 2015, the rate of reported primary and secondary syphilis in the United States was 7.5 cases per 100,000 population, nearly four times the previous lowest documented rate of 2.1 in 2000 (1). In 2015, 81.7% of male primary and secondary syphilis cases with information on the sex of the sex partner were among gay, bisexual, and other men who have sex with men (collectively referred to as MSM) (1). These data suggest a disproportionate incidence of disease among MSM. However, attempts to quantify this disparity have been hindered by limited data on the size of the MSM population at the state level. To produce the first estimates of state-specific rates of primary and secondary syphilis among MSM, CDC used MSM population estimates based on a new methodology (2) and primary and secondary syphilis case counts reported in 2015 to the National Notifiable Diseases Surveillance System. Among 44 states reporting information on the sex of sex partners for ≥70% of male cases, the overall rate of primary and secondary syphilis among all men (aged ≥18 years) in the United States in 2015 was 17.5 per 100,000, compared with 309.0 among MSM and 2.9 among men who reported sex with women only. The overall rate of primary and secondary syphilis among MSM was 106.0 times the rate among men who have sex with women only and 167.5 times the rate among women.* These data highlight the disproportionate impact of syphilis among MSM and underscore the need for innovative and targeted syphilis prevention measures at the state and local level, especially among MSM. It is important that health care providers recognize the signs and symptoms of syphilis, screen sexually active MSM for syphilis at least annually, and provide timely treatment according to national sexually transmitted diseases treatment guidelines (3). Case reports of primary and secondary syphilis cases for MSM, men who have sex with women only, and women were obtained from national data reported regularly by all states for 2015. These data include limited demographic and clinical information, including the sex of sex partners. Population estimates of the number of MSM by state were obtained using new methodology that makes use of census and population-based survey data (2). To estimate the MSM population size, the estimated percentage of MSM among men was adjusted (4) according to each U.S. county's percentage of households with a male head and a male partner, obtained from American Community Survey summary data and urban-rural classification (large central metropolitan, large fringe metropolitan, * In this report "women" is used to describe both females aged ≥18 years (used for calculating rates for women) and females of unknown ages (used for calculating rates for men who had sex with women only).