After appropriate treatment, syphilis does not recur. However, having syphilis once does not protect a person from becoming infected again. Even following successful treatment, people can be reinfected. Patients with signs or symptoms that persist or recur or who have a sustained fourfold increase in nontreponemal test titer probably failed treatment or were reinfected. These patients should be retreated.
Because chancres can be hidden in the vagina, rectum, or mouth, it may not be obvious that a sex partner has syphilis. Unless a person knows that their sex partners have been tested and treated, they may be at risk of being reinfected by an untreated partner. For further details on the management of sex partners, refer to the 2015 STD Treatment Guidelines. 3