Updates on epidemiology and diagnostic tests of syphilis in South Korea

Syphilis is a sexually transmitted disease caused by the spirochete Treponema pallidum. Recently, there has been a global resurgence of syphilis cases. In South Korea, the reported rate of syphilis steadily increased from 1.93 per 100,000 individuals in 2011 to 3.41 per 100,000 individuals in 2019. Notably, the incidence of the disease has been rising sharply among men in their 20s and 30s since 2016. Diagnosing syphilis based on its stage is complex and time-consuming. The combination of nontreponemal and treponemal tests has long been the cornerstone of syphilis diagnosis. Automated versions of nontreponemal tests and treponemal immunoassays have replaced the traditional manual nontreponemal and treponemal tests. Additionally, traditional direct methods, such as dark-field microscopy and silver staining, have been replaced by polymerase chain reaction testing and immunohistochemistry. Point-of-care tests are promising tools that facilitate the rapid and easy diagnosis of active syphilis. To ensure the proper diagnosis and control of syphilis, a comprehensive surveillance system and a thorough understanding and appropriate interpretation of diagnostic tests are necessary.