http://www.cdc.gov/std/Syphilis/STDFact-MSM-Syphilis.htm
Centers for Disease Control and Prevention, U.S. Department of Health and Human Services
Over the past several years, increases in syphilis among MSM have been reported. In the recent outbreaks, high rates of HIV co-infection were found. While the health problems caused by syphilis in adults are serious in their own right, it is now known that the genital sores caused by syphilis in adults also make it easier to transmit and acquire HIV infection sexually.