 In 2013 syphilis infected about 315 @,@ 000 people . Syphilis is believed to have infected 12 million additional people in 1999 , with greater than 90 % of cases in the developing world . It affects between 700 @,@ 000 and 1 @.@ 6 million pregnancies a year , resulting in spontaneous abortions , stillbirths , and congenital syphilis . During 2010 it caused about 113 @,@ 000 deaths down from 202 @,@ 000 in 1990 . In sub @-@ Saharan Africa , syphilis contributes to approximately 20 % of perinatal deaths . Rates are proportionally higher among intravenous drug users , those who are infected with HIV , and men who have sex with men . In the United States , rates of syphilis as of 2007 were six times greater in men than women ; they were nearly equal in 1997 . African Americans accounted for almost half of all cases in 2010 . As of 2014 , syphilis infections continue to increase in the United States . 
