Syphilis Makes Big Comeback Cases nearly double in recent years, especially among men By John Johnson, Newser Staff Posted May 8, 2014 4:26 PM CDT 56 comments Comments The bacterium treponema pallidum, which causes syphilis. (Shutterstock) (Newser) – Syphilis cases are rising sharply in the US, especially among gay and bisexual men, reports the CDC. The highest rates were among black men, but white and Hispanic men also saw noticeable increases, reports Reuters. From 2005 to 2013, the number of syphilis cases nearly doubled from 8,724 to 16,663, and 91% of those cases occurred among men in 2013. Over that same stretch, the annual rate rose from 2.9 to 5.3 cases per 100,000 people, reports NBC News. “After being on the verge of elimination in 2000 in the United States, syphilis cases have rebounded," says the CDC report. Researchers warn that the increase among gay men is worrisome because it suggests unsafe sex practices that could also spread HIV. The CDC recommends that men who have sex with anonymous or multiple partners get screened for syphilis at least once every six months. While rarely fatal, the disease can lead to blindness and stroke.