Objective: Syphilis and human immunodeficiency virus (HIV) are sexually transmitted infections that share common risk factors and may facilitate each other’s transmission. This study aimed to evaluate the frequency of syphilis coinfection among individuals living with HIV over a five-year period.
Materials and Methods: In this retrospective study, anti-HIV, rapid plasma reagin (RPR), Treponema pallidum hemagglutination assay (TPHA), Treponema pallidum total immunoglobulin, and HIV confirmatory test results of individuals aged ≥18 years were evaluated between 2020 and 2024. Patients who had both HIV- and syphilis-related tests during the period of HIV positivity were included. Syphilis seropositivity was defined according to the institutional diagnostic algorithm based on the combination of treponemal and non-treponemal tests. Active infection was defined as concurrent positivity of treponemal and RPR tests, whereas isolated treponemal positivity was considered a past infection.
Results: Among 200 individuals living with HIV, 162 underwent syphilis testing. Of these, 85.5% were male. Syphilis seropositivity was detected in 41 patients (25.3%), including 24 (14.8%) with active infection and 17 (10.5%) with past infection. No significant differences were observed based on age, sex, or year (p>0.05). During the same period, syphilis seropositivity among HIV-negative individuals was 0.96%. HIV positivity was strongly associated with syphilis seropositivity (OR: 34.8; 95% CI: 23.1–52.6; p<0.001).
Conclusion: The high rate of syphilis seropositivity among HIV-positive individuals underscores the importance of routine screening at diagnosis and during follow-up.