“…6 In the United States in the past decade, this increase has particularly affected men who have sex with men (MSM) and, more recently, young African-Americans and Hispanics. 7,8 Similar trends for MSM have been observed throughout Europe 9 and China. 3,10,11 Some reports suggest that the increasing incidence of syphilis may be due to high-risk behaviours, such as methamphetamine use, 12-14 but as we will discuss later, the higher rates of syphilis and HIV coinfection may also be due to immunological factors.…”