Treatment of Secondary Syphilis Relapse and Reinfection

Distinguishing Relapse from Reinfection

The Centers for Disease Control and Prevention (CDC) characterizes relapse as persistent or recurrent signs/symptoms after appropriate treatment without new exposure, while reinfection occurs after new sexual exposure to an infected partner 2
Both conditions present with similar clinical manifestations, including recurrence of symptoms or a sustained fourfold increase in nontreponemal test titers 1, 2

The CDC recommends performing a thorough clinical evaluation and serologic testing with nontreponemal tests (RPR or VDRL) for both conditions 4
Treatment failure (relapse) should be suspected if there is no fourfold decrease in titer within 6 months after therapy for secondary syphilis 2, 4
CSF examination is recommended in cases of suspected treatment failure/relapse to rule out neurosyphilis, unless reinfection is clearly established 1, 2
HIV testing should be performed in all patients with suspected treatment failure or reinfection 5

The CDC recommends administering benzathine penicillin G 2.4 million units IM once weekly for 3 weeks for relapse cases 1, 2
For reinfection cases, the CDC recommends administering a single dose of benzathine penicillin G 2.4 million units IM 1, 2

The CDC recommends clinical and serologic follow-up at 3-month intervals for relapse cases 2, 3
For reinfection cases, follow-up at 6 and 12 months after treatment is recommended 1, 2
HIV-infected patients should be evaluated more frequently (every 3 months) regardless of whether they experienced relapse or reinfection 5, 4

Some patients may remain serofast (persistent low-level positive titers) despite adequate treatment, which does not necessarily indicate treatment failure 4
HIV-infected patients may have atypical serologic responses and slower serologic clearance after treatment 5, 4

The CDC advises against comparing titers between different test types (e.g., VDRL vs. RPR) as they are not directly comparable 4
The CDC also advises against assuming that persistent low-titer reactivity necessarily indicates treatment failure or reinfection 4
Never skip CSF examination in cases of suspected treatment failure unless reinfection is clearly established 2, 3