Evaluation of Early Syphilis and Sexual Risk Behavior in Denver, Colorado

Background:In Denver, early syphilis increased 151% from 2007 to 2010 .  This rise is largely due to increases among men who have sex with men (MSM).

Objectives: To describe the increase in early syphilis and examine the risk behaviors and partner characteristics associated with cases.

Methods: All syphilis diagnoses are reportable to the Colorado Department of Public Health and Environment (CDPHE).  Disease intervention specialists (DIS) collect demographic, behavioral risk, and partner information.  We examined all early (primary, secondary and early latent) syphilis cases diagnosed between Jan 1, 2010 and Dec 31, 2010 in the City and County of Denver.

Results: Of the 167 cases, 95% were among MSM.  61% of MSM were also HIV positive at diagnosis.  The majority of cases were white, non-Hispanic (61%), 23% identified as Hispanic and 11% were black, non-Hispanic.  The mean age at diagnosis was 37 years old. Approximately 40% of cases reported meeting sex partners on the internet, 21% in bathhouses, 17% in bars or clubs, and 4% in bookstores.  A small proportion (4%) reported exchanging sex for money, drugs, or shelter and 43% reported sex with anonymous partners. At the time of diagnosis, 6.6% were co-infected with urethral chlamydia, 1.8% with urethral or rectal gonorrhea and 3% were newly diagnosed with HIV. Of all partners that DIS were able to contact, 25% were positive for early syphilis.  Of these, 56% were HIV positive and 98% MSM.  

Conclusions: Syphilis disproportionally affects the MSM population.  These increases in MSM may be due to increased risky sexual behavior following the success of anti-retroviral therapy and the perception that HIV is no longer a serious problem.  

Implications for Programs, Policy, and Research: Examining risk behavior and partner information helps public health officials gain a better understanding of were outreach and education efforts must be focused.