AIDS mortality may have contributed to the decline in syphilis rates in the United States in the 1990s

Background: The mortality associated with AIDS among men may have had an influence on primary and secondary syphilis trends among men in the United States, through the loss of men at high risk for acquisition or transmission of syphilis in this population and/or by prompting safer sexual behaviors in response to the threat of AIDS. Goal: The goal of this study was to examine the association between AIDS mortality rates and primary and secondary syphilis incidence rates among men in the United States from 1984 to 1997. Study Design: We used a fixed-effects regression analysis of state-level AIDS mortality rates and primary and secondary syphilis incidence rates for men. Results: Our analysis showed a significant association between higher AIDS mortality and lower rates of syphilis incidence, after we controlled for confounding factors. Our model estimates suggested that every 20 AIDS deaths per 100,000 adult men are associated with declines of about 7% to 12% in syphilis incidence rates among men. Conclusion: Increases in AIDS-associated mortality may have accounted for one-third to one-half of the decline in syphilis rates among men in the early 1990s. Recent declines in AIDS mortality in the United States may have contributed to the recent outbreaks of syphilis, particularly among men who have sex with men. Our findings underscore the importance of providing STD prevention services to men with HIV infection and the need for STD surveillance in communities at risk for syphilis outbreaks.