Syphilis treatment and HIV infection in a population-based study of persons at high risk for sexually transmitted disease/HIV infection in Lima, Peru

Objectives: The objective of this study was to characterize syphilis epidemiology and the relationship of HIV status and initial rapid plasma reagin (RPR) titer to syphilis treatment in Lima, Peru. Study Design: We screened 1,261 individuals at high risk for sexually transmitted diseases for syphilis and HIV infection. Syphilis was treated with penicillin injection or doxycycline; treatment was repeated in unresponsive cases. Results: The prevalence of syphilis was 7.7%, 1-year incidence rate was 4.7%, and reinfection rate was 42.7%. The treatment success rate was 93.4% (71 of 76); those with initial RPR titers ≤1:8 were less often treated successfully (86.8% vs. 100%, P = 0.054) and required additional treatment more often (26.2% vs. 7.7%, P = 0.028) than those ≥1:16. HIV infection was associated with syphilis, prevalent in 15.6% and 3.7% of those with and without syphilis, respectively (P < 0.001), but did not affect treatment success (90.9% vs. 93.8%). Conclusions: Syphilis was common, associated with HIV infection, and less responsive to therapy in those with initial RPR titers ≤1:8. HIV infection did not affect syphilis treatment success rates.