Syphilis is a sexually-transmitted infectious disease caused by the spirochete Treponema pallidum. Syphilis has three main stages: primary syphilis, secondary and tertiary syphilis. Approximately one-third of untreated individuals with primary syphilis will progress to the second stage: secondary syphilis. This usually occurs at about 2 to 8 weeks after the appearance of the original painless sore (chancre) and in some cases the chancre may still be present.

Secondary syphilis is the stage where the bacteria have spread in the bloodstream and have reached their highest numbers. The most common symptoms include skin rash which can be varied in appearance, yet frequently involves the palms and soles, in addition to lesions in the mouth, vagina, penis called mucous patches. Other lesions which can also appear are moist warty patches on the genitalia or skin folds called condylomata lata. During secondary syphilis additional symptoms such as fever, malaise, anorexia, and swollen lymph nodes may also be noted. This stage is the most contagious stage of syphilis. While it usually resolves within weeks, in some cases it may last up to a year.