Background

The incidence of many STDs in gay, bisexual, and other men who have sex with men (collectively referred to as MSM) – including primary and secondary (P&S) syphilis and antimicrobial-resistant gonorrhea – is greater than that reported in women and men who have sex with women only (MSW).1-6 In addition to the negative effects of untreated STDs, elevated STD burden is of concern because it may indicate high risk for subsequent HIV infection. Annual increases in reported STD cases could reflect increased frequency of behaviors that transmit both STDs and HIV (e.g., condomless anal sex), and having an STD increases the risk of acquisition or transmission of HIV.7-14

The relatively high incidence of STD infection among MSM may be related to multiple factors, including individual behaviors and sexual network characteristics.15-17 The number of lifetime or recent sex partners, rate of partner exchange, and frequency of condomless sex each influence an individual’s probability of exposure to STDs.15 However, MSM network characteristics such as high prevalence of STDs, interconnectedness and concurrency of sex partners, and possibly limited access to healthcare also affect the risk of acquiring an STD.15, 18 Furthermore, experiences of stigma – verbal harassment, discrimination, or physical assault based on attraction to men – are associated with increased sexual risk behavior among MSM.19

Disparities among MSM reflect those observed in the general population, with disproportionate incidence of STDs reported among racial minority and Hispanic MSM, MSM of lower socioeconomic status, and young MSM.20-24 The higher burden of STDs among MSM with these characteristics, relative to the general population of MSM, may suggest distinct mixing patterns in their sexual networks, reduced access to screening and treatment, and differential experiences of stigma and discrimination, rather than greater numbers of sexual partners or frequency of condomless sex.15, 21-22, 24-26 Furthermore, disparities may be more pronounced for racial minority and Hispanic MSM who are also unemployed, young, and/or of lower socioeconomic status.26-27

With the exception of reported syphilis cases, nationally notifiable STD surveillance data do not routinely include information on sexual behaviors, and these data are missing for the majority of gonorrhea and chlamydia cases reported to CDC. Therefore, trends in STDs among MSM in the United States are based on findings from sentinel and enhanced surveillance systems. Testing strategies are also evolving to include more extragenital STD screening, which may increase detection of asymptomatic infections. Until recently, testing for gonorrhea and chlamydia in MSM largely focused on detecting urethral infections, which are more likely to be symptomatic than pharyngeal or rectal infections.28

For data reported in this chapter, MSM were defined as men who either reported having one or more male sex partners or who self-reported as gay/homosexual or bisexual. MSW were defined as men who reported having sex with women only or who did not report the sex of their sex partner, but reported that they considered themselves straight/heterosexual. Data presented in this chapter are derived from the National Notifiable Diseases Surveillance System (NNDSS), the Gonococcal Isolate Surveillance Project (GISP), and the STD Surveillance Network (SSuN), a sentinel and enhanced surveillance project established in 2005 to provide supplemental information on STDs.