Hidden In Plain Sight: A Public Health Cross-Sectional Project to Address Syphilis and HIV in South Central South Dakota's Incarcerated Populations.

Introduction: Syphilis, caused by Treponema pallidum, is a major public health concern, particularly in high-risk populations like incarcerated individuals. Timely diagnosis remains challenging, especially in rural and frontier communities. This study aims to assess the effectiveness of point-of-care (POC) syphilis and HIV testing at the Winner City Jail in South Dakota, a rural correctional facility with a high prevalence of syphilis and HIV risk factors.

Methods: This 12-week cross-sectional study (October 2 to December 19, 2024) tested new intakes from nine counties without prior syphilis or HIV history. POC testing was performed using the Chembio DPP HIV-Syphilis immunoassay, followed by confirmatory testing (RPR for syphilis, NAAT for HIV). Demographic and risk factor data were collected via interviews, and treatment was administered based on diagnosis.

Results: Of the 112 individuals tested, seven (6.3%) had reactive syphilis results, all confirmed by RPR testing. One individual tested positive for HIV on POC, but negative on confirmatory testing. Most syphilis cases were late latent stages (86%), and all were asymptomatic. Risk factors included unprotected sex, substance use, and prior incarceration.

Conclusion: POC testing effectively identified syphilis and HIV in a rural correctional setting, enabling early diagnosis and treatment. While the Chembio test was highly accurate for syphilis, the false positive for HIV emphasizes the importance of confirmatory testing. Expanding this approach to other correctional facilities could reduce STI transmission in high-risk populations. Further studies are needed to assess long-term outcomes and expand testing to other STIs.