ABSTRACT
Syphilis is caused by the spirochete bacterium Treponema pallidum pallidum. Its genome is almost identical to those of the treponemes causing yaws (T. pallidum pertenue), pinta (T. carateum) and endemic syphilis (T. pallidum endemicum). These three conditions are not sexually transmitted but they are worthy of mention here because of the diagnostic confusion they can sometimes cause (see below).
