Epidemiology of syphilis
Syphilis is believed to have infected 12 million 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. In Sub-Saharan Africa syphilis contributes to approximately 20% of perinatal deaths.In the developed world, syphilis infections were in decline until the 1980s and 1990s due to widespread use of antibiotics. Since the year 2000, rates of syphilis have been increasing in the US, UK, Australia and Europe primarily among men who have sex with men. This is attributed to unsafe sexual practices.Increased rates among heterosexuals have occurred in China and Russia since the 1990s. Syphilis increases the risk of HIV transmission by two to five times and co-infection is common (30–60% in a number of urban centers).Untreated it has a mortality of 8% to 58% with a greater death rate in males. The symptoms of syphilis have become less severe over the 19th and 20th century in part due to widespread availability of effective treatment and partly due to decreasing virulence of the spirochete. With early treatment few complications result.