Syphilis Prevalence and Incidence 6% and 8% in HIV+ US Military

Nearly 6% of HIV-positive US Department of Defense beneficiaries had syphilis when first tested, and syphilis developed in 8% during 25 years of follow-up.

Syphilis rates have surged among HIV-positive people over the past 20 years, most notably in men who have sex with men with and without HIV. Because members of the military are usually young and sexually active, these researchers set out to determine syphilis prevalence (the overall rate at a given time) and incidence (the new infection rate for a specified period) in HIV-positive military members. These people have unrestricted free access to care.

Among 3482 people tested for syphilis at HIV diagnosis, 202 had syphilis to yield a prevalence of 5.8%.

The incidence calculation involved 4239 participants contributing 27,192 person-years of follow-up. In this group, syphilis developed in 347 (8.2%) to yield an incidence of 1.3 cases per 100 person-years (95% confidence interval 1.1 to 1.4). Syphilis incidence was highest in the years 2006 through 2009.

Multivariate analysis identified six independent predictors of syphilis at the following hazard ratios (HR) (and 95% confidence intervals):

Lowered syphilis risk:
• Every 10 years older age: HR 0.8 (0.8 to 0.9)

Raised syphilis risk:
• Male gender: HR 5.6 (2.3 to 13.7)
• African-American vs European ancestry: HR 3.2 (2.5 to 4.2)
• Hispanic vs European ethnicity: HR 1.9 (1.2 to 3.0)
• History of hepatitis B: HR 1.5 (1.2 to 1.9)
• History of gonorrhea: HR 1.4 (1.1 to 1.8)

The authors believe the high syphilis rates observed suggest a need to study the cost-effectiveness of extending syphilis screening to at-risk military members. The persistently high syphilis incidence, they add, emphasizes “the continued importance of prevention for positive programs.”

Source: Anuradha Ganesan, Ann Fieberg, Brian K. Agan, Tahaniyat Lalani, Michael L. Landrum, Glenn Wortmann, Nancy F. Crum-Cianflone, Alan R. Lifson, Grace Macalino, the Infectious Disease Clinical Research Program HIV Working Group. Results of a 25-year longitudinal analysis of the serologic incidence of syphilis in a cohort of HIV-infected patients with unrestricted access to care. Sexually Transmitted Diseases.. 2012; 39: 440-448.

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Written by Mark Mascolini on behalf of the International AIDS Society