In bivariate analyses, men who reported using both methamphetamines and sildenafil while having sex in the prior 4 weeks were over 7 times more likely to have early syphilis than men who did not use these drugs. In contrast, men who used methamphetamines without sildenafil were more than 4 times as likely to have early syphilis compared to nonusers, and men who used sildenafil without methamphetamines were at similar risk for early syphilis than nonusers. Men who used other drugs in the 4 weeks before the clinic visit were more than twice as likely to be diagnosed with early syphilis compared to nonusers. Other drugs included cocaine, poppers, GHB, ecstasy, and ketamine used in the previous 4 weeks while having sex. Reported alcohol use appeared to have a modest protective effect. Men who used the Internet and those who used phone sex lines to meet sex partners in the 4 weeks before the clinic visit were over 2 times more likely to be diagnosed with early syphilis than men who did not use these venues. Adult bookstores, bars/clubs, circuit parties, sex clubs, bathhouses, parks and other public places were not significant in bivariate analyses.
We found that HIV infection, methamphetamine use especially with sildenafil, meeting recent sex partners on the Internet, nonwhite race, and stronger gay community affiliation were associated with an increased risk of early syphilis infection among gay and bisexual men seen at San Francisco City Clinic.
Clinical manifestations of syphilis are altered in HIV-infected persons who may present with multiple chancres in primary syphilis, overlapping clinical features of primary and secondary stages, higher syphilis serological titers at baseline, and slower serological declines following treatment.13,14 Syphilis infection can increase HIV viral load and decrease CD4 cell counts in HIV-infected persons and therefore may accelerate the progression of HIV disease and enhance the risk of HIV transmission.15,16 Because of the detrimental effects of syphilis in persons with HIV infection and because the majority of HIV-infected persons receive routine HIV care in San Francisco, HIV care providers should have an important role in syphilis prevention efforts. In addition to syphilis screening, testing, and treatment services, HIV care providers can provide behavioral risk reduction counseling and health education for persons at risk for syphilis. Local health departments can implement health provider awareness campaigns with a special focus on HIV care providers by issuing medical alert letters, provider visitations, educational lectures, and focused communications such as correspondence letters and e-mail notices to increase the awareness of syphilis among providers and provide continuing medical education on syphilis symptom recognition and management recommendations.
Both methamphetamine and sildenafil use has been associated with higher risk sexual behaviors, including engaging in unprotected anal sex, having an increased number of sexual partners, and with the acquisition of sexually transmitted diseases, including HIV, among MSM in different settings.17–24 In addition, methamphetamine use has been associated with impaired adherence to antiretroviral medication regimens and increased HIV viral loads among HIV-positive active methamphetamine users,25,26 thereby potentially increasing HIV transmission risk in this population. We found that men who used methamphetamine without sildenafil were at increased risk for syphilis infection, whereas men who used sildenafil without methamphetamine were not at increased risk for syphilis infection. Furthermore, the combined use of methamphetamine with sildenafil substantially increased the risk for syphilis infection among gay and bisexual men in this study. This interaction between sildenafil and methamphetamine use may reflect the social context in which these substances are used and is consistent with reports of the use of sildenafil to counteract the erectile dysfunctional effects of methamphetamines, leading to higher-risk sexual behaviors that facilitate syphilis transmission.27 Because of the strong association between early syphilis and methamphetamine use, especially with sildenafil, substance-abuse-prevention efforts should be integrated into broader STD and HIV control strategies. Several studies describe reductions in sexual-risk behaviors among gay and bisexual men following substance abuse treatment.28–30 Local health departments can collaborate with methamphetamine-abuse treatment programs to increase the awareness of syphilis among providers and clients and to encourage syphilis testing as a routine part of the treatment intake evaluation. Physicians can intervene by educating patients about sexually transmitted diseases in addition to providing general sex education and sexual risk reduction counseling for patients and partners before prescribing sildenafil.31 Public health leaders can educate health providers about STD and HIV counseling messages to share with patients when prescribing sildenafil and other drugs used to treat erectile dysfunction. Public health leaders can also work with the pharmaceutical industry to directly educate users of sildenafil about the risk of STD and HIV transmission associated with sexual-risk behaviors.32
The emergence of the Internet as a place where persons diagnosed with syphilis and other STDs meet sexual partners has challenged public health agencies to expand outreach and prevention efforts in this setting.6,33–37 In San Francisco, Internet-based prevention interventions have included the development of a website (www.sfcityclinic.org), the creation of internet links to syphilis testing services, individual outreach in Internet chat rooms and public message boards, health-promotional banner advertisements, the development of an e-mail listserv to distribute syphilis updates, the creation of an online syphilis-testing program (www.stdtest.org), and collaboration with officials at Gay.com to develop and implement “Ask Dr. K,” an internet-based STD educational question and answer service.38–41 Because of the association between early syphilis and meeting sex partners online, Internet-based health promotion and disease prevention for MSM should continue, along with other syphilis-prevention activities.
Racial and ethnic disparities in syphilis rates continue to persist in the United States.42 Higher prevalence rates of HIV and STDs and differential sexual-risk behaviors among MSM of color compared to white MSM demonstrate that racial and ethnic disparities in health also exist among MSM.43,44 Racial and ethnic disparities may indicate markers for differences in sexual risk behaviors, socioeconomic status, sexual networks, social support, social disenfranchisement, and marginalization among MSM of color.45–47 The higher risk for syphilis among nonwhite gay and bisexual men suggests that continued efforts to prevent and control syphilis incidence in these populations are needed.
Finally, since we observed that gay and bisexual men with high levels of community affiliation were more likely to have syphilis than men with low levels of community affiliation, these data confirm the importance of collaborating with gay community organizations and media outlets, inclusive of gay communities of color, to address the syphilis epidemic in San Francisco. Public health departments can partner with gay community-based organizations including local gay community centers and HIV/AIDS service and prevention organizations. Public health departments should involve community-based organizations in planning syphilis-prevention activities through community collaboration and advisory committees. The San Francisco Department of Public Health has embraced an innovative social marketing campaign to reach gay and bisexual men at risk for syphilis (www.healthypenis2004.org)48,49 and has partnered with a local gay men’s community health organization50 to increase community access to syphilis testing and treatment services in San Francisco. Involvement of the gay community potentially could have a tremendous impact in controlling the syphilis epidemic in San Francisco by reaching at-risk persons who would not ordinarily use STD services in traditional clinical settings.
There are several potential limitations to our findings. First, similar to case-control studies, this cross-sectional study design limits the inferences we can make on causality. However, an advantage of the cross-sectional design used in this investigation is that exposure and outcome were obtained simultaneously, and therefore potential recall bias is minimized. Second, these findings may not be generalizable to all gay and bisexual men in the community. Because gay and bisexual men who seek care at the municipal STD clinic most likely have higher-risk sexual behaviors than men seen outside of the public sector, these findings are probably more representative of gay and bisexual men with higher-risk sexual behaviors in San Francisco. Last, self-reported behavior is subject to bias that includes the underreporting of socially stigmatized behaviors, and therefore our findings might underestimate the level of risk for gay and bisexual men diagnosed with early syphilis.
More studies are needed to assess the increases in syphilis among MSM in local jurisdictions and nationally to further elucidate risk factors for infection. A better understanding of risk factors for syphilis infection among MSM can inform the public health programmatic response to more effectively target higher-risk subpopulations of MSM. Changes in the HIV epidemic and the emergence of the Internet have influenced sexual behaviors, partnering patterns, and sexual networks, in addition to the social and cultural factors that impact syphilis prevention and control efforts. Innovative programs, along with intervention evaluations, are needed to prevent and control syphilis in the community.
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