Syphilis is a sexually transmitted disease caused by the pale spirochete. It can produce a variety of symptoms, the most common of which are painless vulvar ulcers (stage 1 syphilis) and a generalized non-pruritic rash (stage 2 syphilis), the former usually occurring 2 to 4 weeks after infection and the latter 7 to 9 weeks. Most of the early symptoms of syphilis infection are mild, painless and do not itch, and can subside on their own within a few weeks without treatment, in a latent state, called latent syphilis. Most patients are found to have syphilis in the latent state. Those infected within two years are considered to have early syphilis, while those infected after two years are considered to have late syphilis. Early syphilis is highly contagious and can be cured by regular treatment; late syphilis is difficult to cure by active treatment, but is less contagious. The diagnosis of syphilis mainly relies on laboratory tests, which are currently based on serological tests, namely the non-syphilis spirochete antigen test (RPR and TRUST are most commonly used) and the syphilis spirochete antigen test (TPPA is most commonly used). The former is a quantitative test, positive results show 1:1, 1:2, 1:4 ……, in increasing order, generally the higher the titer indicates the more pathogens in the body, the more infectious, the titer will gradually decline after treatment until it turns negative. Early syphilis (within two years of infection) after regular treatment, about 90% of patients RPR or TRUST can be turned negative and cured, the time about 1 to 1.5 years. Late syphilis (after two years of infection) can decrease in titer after treatment, and it is more difficult to turn negative and recover, but as long as the titer is maintained at a low level (less than or equal to 1:8), it is less harmful to the body and less infectious. A positive TPPA test is not the basis for a current syphilis infection. The diagnosis of syphilis requires both serologic tests to be positive, and only one positive test does not necessarily mean syphilis. Acute infectious diseases such as rubella and measles, autoimmune diseases, and pregnancy can show positive RPR or TRUST, but the titer is low, usually less than or equal to 1:8, which is called a false positive. In very rare cases, the above-mentioned conditions may also show a positive TPPA, but generally not both serologic tests are positive. There is also the early stage of syphilis infection (2 to 4 weeks) when only one of the tests is positive, when there is often a rash such as vulvar ulcers, and then after 2 to 4 weeks of rechecking, both serological tests turn positive. In conclusion, once the syphilis serology test is only one positive, only regular rechecking is needed. If the results are positive for one of them several times, you can basically rest assured that it is either a false positive or a previous syphilis infection that has now been cured and is not contagious. So, how can syphilis heal itself without knowledge and without formal treatment? This is because the syphilis spirochete is sensitive to drugs such as penicillin and erythromycin, and the infected person may have been cured of syphilis by the use of said drugs for other diseases. Even if the serologic test is positive for both, it is not necessarily infectious. Most late-stage latent syphilis (after two years of infection), especially those with low titers (less than or equal to 1:8) are very weakly infectious.