How can I tell if my syphilis has healed after treatment? The RPR (Rapid Plasma Reactin Ring Card Test) and TPHA (Syphilis Spirochete Haemagglutination Assay) are commonly used in major hospitals to determine this. The RPR is a non-specific syphilis serological test, commonly used for early diagnosis of syphilis, but is not sensitive to latent syphilis, neurosyphilis. TPHA detects specific syphilis spirochete antibodies in the serum and has high sensitivity and specificity. Once the test is positive, it usually remains positive for life, regardless of treatment or disease activity, and its titer changes are not related to syphilis activity, so it cannot be used as an indicator to evaluate the efficacy of treatment or to determine recurrence or reinfection, but only as a confirmation test for syphilis. For those who are diagnosed with syphilis, it is best to do a quantitative test before treatment. A decrease in titer can only be judged when there is a difference of more than 2 dilutions between the two quantitative tests. After regular treatment, syphilis patients should have their RPR titers rechecked once a month for the first three months, and then every three months for the next year, and every three months or every six months for the second year, in order to observe and compare the changes in RPR titers between the current and the previous ones. Therefore, the follow-up observation of syphilis patients after treatment is usually over a period of two years. If the titer of RPR of each test shows a decreasing trend, it means that the anti-syphilis treatment is effective. If the results of three to four consecutive tests are negative, the patient is considered to be cured of syphilis. There are generally three possible changes in the serologic response of a patient with syphilis after anti-syphilis treatment: 1. seronegative 2. A decrease in serum titer without negative transformation, or serum resistance. 3. Serologic response indicating relapse. The rate of seronegativity can vary among the different stages of syphilis treated with different drugs. Early syphilis treated with any anti-syphilis drug, seroconversion rate is high, usually up to 70%-95% within 1 year, some reports up to 100%. When the seropositivity is maintained 6 months after regular anti-syphilis treatment for early syphilis or 12 months after regular anti-syphilis treatment for late syphilis, it is clinically called seroresistance or serofixation, which may be related to the presence of potentially active lesions in the body, persistent immunity of the patient, insufficient dose of anti-syphilis treatment or drug resistance. Substantial neurosyphilis of stage III syphilis (e.g., spinal consumption, paralytic dementia) still occurs in 50% to 80% of patients with serum resistance even after long-term regular anti-syphilis treatment. Early diagnosis, early treatment, and a full course of therapy are the best means of avoiding the development of serum resistance. If a syphilis patient receives an insufficient amount of anti-syphilis treatment, the seropositive reaction can turn positive again soon after a temporary negative change, or the titer increases fourfold (e.g., from 1:2 to 1:8), which is called “seropositive relapse”, which shows that there is a close relationship between the regular and adequate amount of anti-syphilis treatment and seropositive relapse. In conclusion, it is advisable to treat syphilis early and regularly, and the efficacy of anti-syphilis treatment can be observed by comparing the RPR titer before and after.