Negative syphilis TPPA, often referred to as negative syphilis spirochete gelatin agglutination test, is a kind of syphilis spirochete antigen serologic test, and its negative means that the patient is not infected with syphilis, or is in the window period of syphilis infection. 1. The body is not infected with syphilis: TPPA is a method of detecting syphilis-specific antibodies, the specificity and sensitivity of the test are high, the negative result means that the body does not produce specific antibodies, and is not infected with syphilis this disease. 2. In the window period: the human body can not produce antibodies immediately after infection with syphilis, from infection to produce antibodies, this period is called the window period. Usually less than 4 weeks after infection, TPPA may be negative. It is recommended that patients with high-risk sexual behavior go to a regular hospital in time, and if the syphilis TPPA is negative, it is recommended to retest after 4 weeks to rule out the possibility of syphilis infection.