AN OUTBREAK OF SYPHILIS in men who have sex with men (MSM) was declared in Houston, Texas, in March 2001 after 3 consecutive months in which MSM cases exceeded a locally established monthly outbreak threshold. There were more early syphilis (primary and secondary [P&S] and early latent [EL] cases) among MSM in the first 3 months of the outbreak (17 cases, December 2000–February 2001) than in the 11 months preceding the outbreak (16 cases, January–November 2000). In Houston in 2001, a total of 97 cases of P&S syphilis were reported overall, compared with 73 P&S cases in 2000. Total P&S cases increased again in 2002 (115 cases). This increase was entirely the result of an outbreak of syphilis in MSM. Among MSM, there was a large increase in P&S syphilis cases from 2000 (9 P&S cases in MSM) to 2001 (36 cases) and 2002 (68 cases). Despite the decreases in the number of MSM early syphilis cases in the third quarter of 2001, the number of cases rose in subsequent quarters, peaking in 2002 at almost double the 2001 outbreak level (Fig. 1).
Although the number of early syphilis cases overall in Houston between 2000 and 2002 rose slightly, the proportion of early syphilis cases in Houston that were attributable to MSM increased dramatically. In 2000, MSM accounted for 10% of the early syphilis cases in Houston compared with 2001 (26%) and 2002 (47%) (Table 1). In 2000, the majority (62%) of early syphilis MSM cases occurred in non-Hispanic blacks, but during the outbreak, cases in non-Hispanic whites increased from 20% to 45% of cases, and non-Hispanic blacks (35%) became responsible for a correspondingly smaller proportion of cases.
Overall, HIV coinfection remained stable at 47% of all early syphilis cases during 2000 to 2002. However, this underestimated the true prevalence of HIV infection because 19% of the MSM diagnosed with early syphilis infection in 2001 and 2002 had unknown HIV status. Of the 137 MSM with known HIV status, 58% were HIV-positive and 55% of these had documentation of a prior HIV-positive diagnosis at the time of syphilis diagnosis.
Figure 1 shows the increasing number of MSM early syphilis cases from 2000 through 2002, and shows that this increase did not occur among non-MSM during the same time period (Table 1). This decline of early syphilis in females and heterosexual males is a continuation of the decreasing trend observed throughout the 1990s, whereas the recent increases in MSMs is a distinct change from the trend observed during the 1990s.
MSM syphilis patients in Houston are reporting anonymous sexual contacts met through chat rooms, web sites, bathhouses, bookstores, bars, parks, and other settings conducive to the anonymous encounter. An apparent resurgence in risky sexual behaviors could be in part the result of improvements in HIV medications that could be lowering the perceptions of risk of AIDS, therefore increasing sexual risk-taking, as has been surmised elsewhere. 1,2 In Houston, data on anonymous sex and anonymous sexual venues have not been systematically collected. The same holds true for collection and analysis of specific drug use, especially designer and the so-called party drugs that are reportedly common in the Houston MSM party scene. Systems have now been implemented to better collect and facilitate rapid, accurate analysis of this information for future use in adapting interventions to better contain the epidemic.
There were several limitations in the available data used for this report. Only cases of syphilis with laboratory serologic confirmation were included, which has the potential to underestimate the number of cases, missing those individuals who are treated for symptoms without a laboratory test as well as incubating cases that have not yet seroconverted. In addition, risk behavior information is only collected from those individuals who test positive for syphilis, so the same risk information was not available for those who tested negative. Thus, a comparison in risk-taking among infected MSM and their noninfected counterparts was not possible. Analysis of HIV coinfection was also limited by inconsistencies in documentation inherent in surveillance data. Increases were seen in key risk behaviors like no condom use and trading sex for drugs or money; however, the small number of MSM early syphilis cases in 2000 (before the outbreak) made conclusions regarding significant changes in risk-taking behavior difficult.
There is a need to strengthen outreach and screening programs, and to implement innovative interventions to reduce risk-taking behaviors. Houston MSM syphilis cases decreased in the summer of 2001 after Houston Department of Health and Human Services (HDHHS) interventions were implemented, but it is not known if this decrease was directly related to intervention efforts, and the decrease was not sustained. Interventions included sending medical alert bulletins to key providers who target MSM clientele. The alerts included information on the increase in cases, the signs and symptoms of syphilis, the need to conduct sexual history-taking to determine risk, and the importance of screening. Rapid treatment and case reporting were also stressed. Syphilis outbreaks such as the one described here are a public health concern both because syphilis is a preventable, treatable disease that can potentially be eliminated and because the presence of syphilis disease increases the likelihood of HIV transmission, thus impacting HIV incidence. The outbreak in Houston joins a growing body of studies documenting increased syphilis cases among MSM communities throughout the United States. 3–6
Of the 80 HIV-positive clients from the outbreak (2001–2002) 44 (55%) already knew they were HIV-positive before contracting syphilis. Syphilis infection in these HIV-positive men is a clear indication of sexual risk-taking and could be a precursor to increased incidence of HIV in the MSM community and beyond. Several studies have demonstrated the difficulty of long-term safer sex compliance. Because some individuals have trouble maintaining safer sex practices for extended periods, 7–10 rapid responses are needed during outbreaks to reinforce risk reduction and to ensure that appropriate treatments are administered to at-risk clients. The MSM syphilis outbreak in Houston, like elsewhere in the country, is a major obstacle to syphilis elimination. There is a need for innovative prevention activities, including more effective partner services and better capturing of risk-taking information to target interventions.
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