1558. Repeat Syphilis Infections in a Cohort of HIV-infected Department of Defense Beneficiaries (DoD), a Thirty Year Study (1986-2015)
Session: Poster Abstract Session: Clinical Infectious Diseases: Sexually Transmitted Infections
Saturday, October 10, 2015
Room: Poster Hall

Since the year 2000 syphilis rates have increased in the US Military Natural History Study (NHS), and nationally increasing numbers of repeat infections have been observed among HIV-infected persons. We used results of serially collected Non-Treponemal titers (NTr) to examine rates, trends and risk factors of repeat syphilis infections in the NHS.


We included NHS subjects who had a serologic diagnosis of syphilis (i.e. a positive NTr test confirmed by treponemal testing). To qualify as a repeat infection we required the following: history of treatment, a four-fold decline in titer following treatment and a subsequent four-fold increase in titer. In subjects with a clinical presentation compatible with reacquisition of syphilis, a documented four-fold decrease in titer between episodes was not required. Adjusting for follow up time, GEE models were used to examine incidence and risk factors associated with repeat syphilis infections. Odds Ratio (OR) and 95% confidence intervals are presented.


A total of 687 subjects with syphilis (99% male, 63% AA, 24% Caucasian) were analyzed; 217 (31.6%) subjects had more than one case of syphilis. The incidence of repeat syphilis infection was highest during the calendar years 2013-2015 (10.4/100 person years [PY]; [7.8, 13.5]). The proportion of new syphilis cases attributable to repeat infections increased over time (p<0.001), table.  In a multivariate model, younger age [Ref >45; age 18-29, OR 2.1 (1.4-3.0); age 30-37, OR 1.8 (1.3-2.6); age 38-44, OR 1.8 (1.3-2.5)], prior history of a sexually transmitted infection [OR 1.4 (1.0-1.7)] and a later calendar time of diagnosis [Ref 1996-2000; <1996, OR 1.7 (0.9-3.1); 2001-2006, OR 2.8 (1.6-4.9); 2007-2012, OR 3.6 (2.1- 6.1); 2013-2015, OR 4.3 (2.4-7.8)] were associated with repeat infections, whereas race, use of erectile dysfunction drugs, and antiretrovirals were not.

Calendar year






Proportion of new cases due to repeat infections







Since 2000 about 40% of all new syphilis diagnoses in the NHS are due to repeat infections. Prevention efforts targeting younger NHS subjects with a recent diagnosis of syphilis and the development of strategies designed to understand the risk behaviors and sexual networks of individuals with repeat syphilis infections may help decrease the burden of disease in HIV-infected persons.

Anuradha Ganesan, MD, MPH1,2,3, Octavio Mesner, MS1,4, Robert Deiss, MD4,5,6, Jason Okulicz, MD, FIDSA4,7, Tahaniyat Lalani, MBBS, MHS3,5,8, Timothy Whitman, DO2,4, Thomas O'bryan, MD4,5,7, Tomas Ferguson, MD, FIDSA4,9, Grace Macalino, PhD4,5 and Brian Agan, MD, FIDSA1,4, (1)Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, (2)Walter Reed National Military Medical Center, Bethesda, MD, (3)Infectious Disease Clinical Research Program, Uniformed Services University of the Health Sciences, Rockville, MD, (4)Infectious Disease Clinical Research Program, USUHS, Rockville, MD, (5)Henry M Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, (6)Naval Medical Center San Diego, San Diego, CA, (7)San Antonio Military Medical Center, Fort Sam Houston, TX, (8)Naval Medical Center Portsmouth, Portsmouth, VA, (9)Tripler Army Medical Center, Honolulu, HI


A. Ganesan, None

O. Mesner, None

R. Deiss, None

J. Okulicz, None

T. Lalani, None

T. Whitman, None

T. O'bryan, None

T. Ferguson, None

G. Macalino, None

B. Agan, None

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