Author: Mark Mascolini
29 July 2010
Swiss HIV Cohort Study (SHCS) researchers detected syphilis in more than 1 in 10 cohort members, often in men who have sex with men (MSM) who engage in oral-genital sex. Almost everyone responded well to treatment.
SHCS investigators introduced annual syphilis testing in the cohort in 2004. This study involved 7244 cohort members prospectively tested for syphilis. Over a period of 33 months, 909 people (12.5%) had a positive syphilis test, including 633 (70%) who had been diagnosed earlier and had no current symptoms.
Among the 218 people with newly diagnosed syphilis, 44 (20%) listed genital-oral sex as their only risk behavior, and 131 (60%) had no syphilis symptoms.
Multivariate statistical analysis determined that being an MSM almost tripled the risk of syphilis (adjusted odds ratio [AOR] 2.8, P < 0.001). Having casual sex partners also almost tripled the risk (AOR 2.8, P < 0.001). Younger MSM had a significantly higher rate of syphilis than older MSM (P = 0.05).
Cerebrospinal fluid tests for syphilis were performed in only 35% of cases that called for such testing. Four people without neurologic symptoms had neurosyphilis, all with a Venereal Disease Research Laboratory (VDRL) titer of 1:>32. Among all cohort members diagnosed with syphilis, 91% responded to treatment with at least a 4-fold drop in VDRL titer.
“Genitooral contact is a significant way of [syphilis] transmission and young MSM are at high risk for syphilis,” the investigators conclude. “Current guidelines to rule out neurosyphilis by CSF analysis are inconsistently followed in clinical practice.”
Source: Maria Christine Thurnheer, Rainer Weber, Laurence Toutous-Trellu, Matthias Cavassini, Luigia Elzi, Patrick Schmid, Enos Bernasconi, Anna B. Christen, Marcel Zwahlen, Hansjakob Furrer, the Swiss HIV Cohort Study. Occurrence, risk factors, diagnosis and treatment of syphilis in the prospective observational Swiss HIV Cohort Study. AIDS. 2010; 24: 1907-1916.
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