Date Published: July 22, 2016
Publisher: Public Library of Science
Author(s): Winston E. Abara, Kristen L. Hess, Robyn Neblett Fanfair, Kyle T. Bernstein, Gabriela Paz-Bailey, Viviane D. Lima.
Globally, men who have sex with men (MSM) are disproportionately burdened with syphilis. This review describes the published literature on trends in syphilis infections among MSM in the US and Western Europe from 1998, the period with the fewest syphilis infections in both geographical areas, onwards. We also describe disparities in syphilis trends among various sub-populations of MSM. We searched electronic databases (Medline, Embase, Global Health, PsychInfo, CAB Abstracts, CINAHL, Sociological Abstracts, Web of Science, Cochrane Library, and LILACS) for peer-reviewed journal articles that were published between January 2004 and June 2015 and reported on syphilis cases among MSM at multiple time points from 1998 onwards. Ten articles (12 syphilis trend studies/reports) from the US and eight articles (12 syphilis trend studies/reports) from Western Europe were identified and included in this review. Taken together, our findings indicate an increase in the numbers and rates (per 100,000) of syphilis infections among MSM in the US and Western Europe since 1998. Disparities in the syphilis trends among MSM were also noted, with greater increases observed among HIV-positive MSM than HIV-negative MSM in both the US and Western Europe. In the US, racial minority MSM and MSM between 20 and 29 years accounted for the greatest increases in syphilis infections over time whereas White MSM accounted for most syphilis infections over time in Western Europe. Multiple strategies, including strengthening and targeting current syphilis screening and testing programs, and the prompt treatment of syphilis cases are warranted to address the increase in syphilis infections among all MSM in the US and Western Europe, but particularly among HIV-infected MSM, racial minority MSM, and young MSM in the US.
Globally, men who have sex with men (MSM) account for a disproportionate burden of syphilis infections [1–3]. In the US, the prevalence rates of primary and secondary syphilis are highest among MSM, particularly among young and minority MSM . In Western Europe, MSM also account for the majority of primary and secondary syphilis cases and remain the group most at risk for contracting syphilis . Primary and secondary syphilis are the most infectious stages of syphilis . Syphilis causes inflammatory genital ulcers and lesions which can increase the risk of HIV transmission by increasing HIV shedding, and acquisition by providing a portal of entry to the HIV virus . Syphilis also complicates the clinical course of HIV by increasing viral load [5, 6]. It has also been associated with a higher rate of treatment failure in HIV-infected persons .
Fig 1 is a flow diagram showing the article screening process. The initial search resulted in 7,673 citations. After removing duplicates, there were 7,014 citations to review for inclusion. Of these, 6,758 citations did not meet the inclusion criteria and 256 citations were retained for retrieval of the full-length article. Review of the full-length articles yielded 39 articles that met the inclusion criteria. If multiple articles reported on overlapping data sources or time points, the most recent or most comprehensive article (larger sample size, more time points, trend data showing disparities by HIV status, race, or age, etc.) was included. Through this process, 16 articles were excluded because they contained duplicate data and outcomes. An additional five articles were excluded because the data were specific to a very high-risk sub-population (i.e., sex workers and incarcerated MSM; n = 3), or because the article described a meta-analysis (n = 2). A final list of 18 articles was used to describe overall syphilis trends for this systematic review. These 18 articles (10 from the US and 8 from Western Europe) included data from independent convenience samples and case surveillance reports from different cities and countries that were considered in this paper to be 24 unduplicated studies.
We examined trends in reported syphilis cases from 1998 and onwards in order to advance our understanding of syphilis disease patterns over time among MSM in the US and Western Europe. The findings of our review showed that syphilis cases increased overall among MSM in the US and Western Europe from 1998. We also found disparities in syphilis trends by HIV status, race, and age among MSM. Among MSM in the US and Western Europe, increases in syphilis cases over time were greater among HIV-positive MSM than among HIV-negative MSM with a corresponding increase in the number of HIV/syphilis co-infections [23, 24, 29, 31, 33, 34, 40]. Racial minority MSM (Black, Hispanic, and API) accounted for a greater increase in the number and rates of syphilis cases over time compared to White MSM in the US [2, 37, 38]. By age group, the greatest increases in the number and rate of syphilis cases over time in the US occurred among MSM between 20 and 29 years [2, 25, 26, 38]. Few studies examined racial and age disparities in syphilis trends among MSM in Western Europe [28, 36]. In Western Europe, because White MSM comprise the majority of MSM, they accounted for the greatest increases in syphilis trends. One study in this review reported a decrease in syphilis cases over time among younger (15–24 years) and older (≥25 years) MSM and there was no study included in this review that examined racial disparities in syphilis trends among MSM in Western Europe.
This review examined trends in reported syphilis cases counts and rates among MSM in the US and Western Europe generally and stratified by HIV status, race, and age. Our findings indicate that the number of syphilis cases and rates among MSM in the US and Western Europe have increased since 1998. Continuous surveillance to monitor, identify, and address syphilis clusters among MSM, sexual risk assessment and counseling during clinical encounters, consistent condom use, frequent syphilis testing and prompt treatment of index MSM cases and their sexual contacts are essential to syphilis control. Innovative evidence-based syphilis prevention interventions for all MSM, but especially HIV-positive MSM in the US and Western Europe and racial minority and younger MSM in the US are needed to reverse the syphilis trends in these subpopulations. Successful implementation of these measures is essential to addressing syphilis among MSM.