Syphilis serum generally refers to the serological test related to syphilis. After the syphilis spirochete infects a person, a large number of antibodies against the syphilis spirochete are produced in the blood circulation. By testing for these antibodies, it is possible to determine whether a person has syphilis and the effectiveness of treatment. There are two types of serological tests, one is the serological test for syphilis spirochete antigen, because the antigen of syphilis spirochete is used, so if the test is positive, it is basically possible to determine the syphilis infection. But once infected, this test will always be positive, even after treatment, it will not become negative, so it can only determine whether it is a syphilis spirochete infection, and not the effect of treatment. The other type of test is the serological test performed by non-syphilis spirochetes antigen, which is a test using non-syphilis spirochetes such as cardiolipin, lecithin, cholesterol, etc. There is usually a titer, and if the titer gradually decreases or even becomes negative with treatment, it means that the corresponding treatment is effective. After a certain period of follow-up, usually one or two years or two or three years, the corresponding titer does not rise again, indicating that the corresponding treatment is effective.