Background: Genital ulcerative diseases, including syphilis, increase the risk of transmitting and acquiring HIV. Since 2000, syphilis has emerged as a significant public health problem. However, there is limited contemporaneous information on the rates and risk factors for syphilis co-infection in those newly diagnosed with HIV.
Methods: We used results of serially collected data to examine rates, trends, and risk factors for syphilis co-infection at HIV diagnosis in the Natural History Study (NHS), a cohort comprised of Department of Defense beneficiaries. Eligible subjects enrolled in the NHS between the calendar years 2000-2012. We defined subjects as having syphilis co-infection if they had a confirmed positive non-treponemal (NTr) test within 6 months of their HIV diagnosis. Baseline risk factors (age, gender, ethnicity, sexual orientation, year of HIV diagnosis) were assessed using a logistic regression model.
Results: Between 2000 and 2012, 1262 [median age 28 years (IQR 23-35), 38% Caucasian, 42% African-American (AA) and 20% Hispanic/Other] subjects had NTr testing performed at HIV diagnosis. The overall prevalence of syphilis co-infection was 8.3% (n=105). In an unadjusted analysis, the prevalence of syphilis at HIV diagnosis increased on average by 2.1% per year (p=0.005). AA ethnicity [Referent {Ref} Caucasian; AA, Odds Ratio {OR} 1.92 (1.18-3.17); Hispanic/Other, OR 1.0 (0.52-1.86)], calendar year of HIV diagnosis [Ref 2000-2004; 2005-2008, OR 2.72 (1.57-4.85); 2009-2012, OR 2.82 (1.57-5.20 ], and MSM behavior [Ref heterosexual; MSM, OR 2.17 (1.04-5.12); other/unknown, OR 1.31 (0.62-3.13)], were associated with concomitant syphilis.
Conclusions: About one in ten NHS subjects had concomitant syphilis at HIV diagnosis. Universal screening for syphilis was discontinued by the US military in the 90s. Our observations suggest the utility of periodic syphilis screening should be re-assessed, especially for at risk military members (AA men and MSM). Such screening programs may reduce incident HIV infections.