Background. The prevalence of syphilis among HIV-infected people is a public health concern, but there is limited literature to describe the true burden of syphilis in resource-limited settings. We conducted this survey in 2013 to estimate the prevalence of syphilis. Methods. A cross-sectional survey. Participants were tested for syphilis and HIV. Factors associated with syphilis infection were identified. Results. The prevalence of syphilis was 0.9% (95% CI: 0.7-1.1). This prevalence was higher in the 25-49-year-old age (1.1% [95% CI: 0.8-1.3]) than in the 15-24-year-old age (0.6% (95% CI: 0.4-0.9)). Women with lower education had a higher prevalence of syphilis (1.2% (95% CI: 0.9-1.5)) compared to others (0.4% (95% CI: 0.2-0.8)). This prevalence among HIV-infected people was six times higher: 4.8% (95% CI: 2.9-7.9) compared to HIV-negative people (0.8% (95% CI: 0.6-1.0)). The prevalence of syphilis among HIV-infected females was 5.9% (95% CI: 3.4-10.0). HIV-infected or concurrent sexual partners was associated with increased syphilis prevalence with aOR = 4.2 (95% CI: 2.5-7.2) and aOR = 4.2 (95% CI: 2.8-6.5), respectively. Conclusions. The prevalence of syphilis was significantly higher among HIV-infected patients. HIV infection and concurrent sexual partners are associated with an increased prevalence of syphilis. Preventing HIV might help in preventing syphilis.