It is a chronic systemic sexually transmitted disease caused by Helicobacter pallidus. The World Health Organization estimates that there are about 12 million new cases of adult syphilis each year worldwide, mainly in developing countries. The number of reports of latent syphilis and fetal syphilis has increased significantly and is mainly distributed in the Yangtze River basin, Pearl River Delta, Beijing-Tianjin region and Xinjiang, Qinghai and Inner Mongolia where the minority groups are relatively concentrated. The immune mechanism of syphilis in human body is still not well understood. Neutrophils and T lymphocytes are found in the skin lesions of stage I syphilis, and specific antibodies can be detected in the blood after the formation of hard chancre, indicating that there is cellular and humoral immune response in stage I syphilis. The immunity in stage II syphilis is in a suppressed state, probably because macrophages temporarily increase the amount of prostaglandin E2 secretion and inhibit IL-2 production, when spirochetes proliferate and syphilis spirochete antibody titers rise. In stage III syphilis, there may be a delayed hypersensitivity response to syphilis antigens, and the damaged tissue phase suggests the possible presence of Toll-like receptor mediation. A number of reports of Toll-like receptors playing a role in syphilis immunity have been published both domestically and internationally. At present, the detection of syphilis is mainly divided into the detection of syphilis spirochetes in tissues and body fluids and serological tests, the former including dark-field microscopy, immunofluorescence staining, silver staining, etc., and the latter including non-specific antibody tests (VDRL, USR, TRUST, RPR) and syphilis spirochete-specific antibody tests (FAT-ABS, TPHA, TPPA, TP-ELISA ). Nowadays, PCR tests are also used, which have higher specificity and sensitivity than serological tests. In recent years, as the incidence of syphilis has increased, the incidence of fetal syphilis has also increased, making the diagnosis and prevention of fetal syphilis very important. Ultrasound testing can also help determine if the fetus is infected, and after 20 weeks of gestation ultrasound can detect changes such as scalp edema, hepatosplenomegaly, placental thickening, and excess amniotic fluid in infected fetuses. The drug of choice for syphilis treatment remains long-acting penicillin, and drugs used for those allergic to penicillin include erythromycin, doxycycline, and tetracycline. The disadvantage of the above drugs is that they cannot cross the blood-brain barrier. Ceftriaxone, as a third-generation cephalosporin antibiotic, can cross the blood-brain barrier and has a therapeutic effect not only on early syphilis but also on neurosyphilis. In recent years, numerous studies have concluded that ceftriaxone can be used as a safe and effective treatment for all stages of syphilis. Tetracycline and doxycycline are prohibited for syphilis in pregnancy. Since syphilis spirochetes can pass through the placenta at 7 weeks of gestation, but fetal infection can not occur before 5 months of gestation, so treatment in the first and last 3 months of gestation can effectively prevent fetal syphilis infection, non-penicillin treatment is less effective, and the infant born should be treated with penicillin supplementation. The titer of the non-syphilis spirochete-specific antibody test should be repeated monthly after treatment during pregnancy to evaluate the efficacy. It may be related to irregular treatment, long duration of disease, neurosyphilis, reinfection and the immune status of the body. Some studies have shown that there is a serious immune imbalance and immunosuppression in patients with serum fixation, mainly in the form of disturbances in the secretion of T-cell subsets, NK cells and cytokines, resulting in a specific response to TP antigens. This leads to a decrease in the intensity of the body’s response to TP antigen-specific hypersensitivity reactions and a decrease in the clearance rate of TP, resulting in a long-term chronic infection with TP latent in the body. Symptoms of syphilis with HIV infection are often atypical, and only 1/3 of stage II syphilis cases are consistent with syphilis symptoms without HIV co-infection. The incidence of ocular syphilis is 10%, cardiovascular syphilis is 10%, and neurosyphilis is 23,5%, all much higher than in uncomplicated syphilis cases. The risk of failure in syphilis patients with co-infection with HIV is higher with benzathine penicillin alone, and the efficacy of combined treatment with penicillin and ceftriaxone may be better, but the number of cases studied is currently limited. Clinical issues 1. When is syphilis most infectious? Untreated syphilis patients are most infectious within 1 year of infection, and their skin and mucosal surfaces contain a large number of syphilis spirochetes. During a complete sexual encounter, the half-infected amount of syphilis (ID50) is about 50 spirochetes, so the infection rate after a single encounter with a patient with stage I and II syphilis is about 30%. Latent syphilis can be transmitted through blood transfusions, but is not generally transmitted through sexual intercourse. The longer the course of syphilis is, the lower the chance of transmission to the fetus, the longer the course of the disease is more than 8 years, the chance of fetal transmission of syphilis is very low. 2.What if I am allergic to penicillin for syphilis in pregnancy? Because penicillin treatment for syphilis in pregnancy is the most important means to prevent fetal infection, we can consider using erythromycin 0,5g orally four times a day for 14 days in the third month of pregnancy, but because erythromycin is very ineffective in preventing fetal syphilis, it is recommended to recheck the non-syphilis heterosexual antibody test monthly, do ultrasonography to exclude fetal infection with syphilis malformation, and in the seventh month of pregnancy Treatment with ceftriaxone, although cross-allergy with penicillin may exist in some populations, ceftriaxone is significantly more effective than erythromycin and the risk is significantly less than penicillin. 3. Do I need a cesarean section for syphilis in pregnancy? Because syphilis spirochetes can pass through the placenta at 7 weeks, most of the fetuses with standard treatment will not develop fetal syphilis, so cesarean delivery does not reduce the rate of fetal syphilis infection. However, in the case of fetuses with fetal syphilis, preterm delivery, placental abruption, intrauterine hypoxia and other adverse pregnancy processes often occur, so these cases often require cesarean delivery to end the pregnancy. 4. What if a pregnant woman with syphilis in pregnancy gives birth to a syphilis-positive baby? If the mother is treated in a timely and regular manner, a positive syphilis-specific antibody does not mean that the baby is infected with syphilis; in the case of a negative non-specific antibody, only regular follow-up is needed, and the syphilis-specific antibody often turns negative within six months to a year; in the case of an infant with a positive non-spirochete antibody and not higher than 2 dilutions of the mother, penicillin prophylaxis can be given and reviewed once a month for 8 months, if the antibody turns negative and does not If the antibodies are negative and no clinical manifestations of congenital syphilis appear, the follow-up can be stopped. Regardless of whether the mother has timely formal treatment, the infant should be treated with penicillin immediately if the titer of non-specific antibody test is higher than 2 dilutions of the mother, or if the titer gradually increases during the follow-up period, or if the clinical manifestations of congenital syphilis appear. 5. How should a patient with syphilis be treated for post-treatment serum fixation? A patient with syphilis is considered to have a fixed serum when the non-specific antibody test is maintained at a certain titer level for a long time after treatment and does not increase or decrease by 2 dilutions. It may be related to the following factors: lack of regular and adequate treatment, neurosyphilis, advanced syphilis, autoimmune factors. Serum fixation of the patient occurred, if the treatment is non-penicillin, then use penicillin treatment and follow up, if already treated with penicillin then extend the follow up time to 3 years, if necessary, cerebrospinal fluid examination to exclude neurosyphilis. 6. What if a patient with syphilis has a serologic relapse after treatment? The possible factors are spirochete insensitivity to therapeutic drugs, neurosyphilis, co-infection with HIV and reinfection. If the patient is not treated with penicillin, first of all, change the treatment to penicillin in sufficient amount, and exclude the infection of HIV, ask the patient in detail whether it is possible to be reinfected and ask his sexual partner to be treated at the same time, for patients who are treated with penicillin and have no possibility of reinfection, cerebrospinal fluid examination is needed to exclude neurosyphilis. 7.How to determine whether the patient has neurosyphilis? Neurosyphilis is divided into asymptomatic type, meningeal vascular type, spinal cord consumption and paralytic dementia. The asymptomatic type often has only cerebrospinal fluid abnormalities without clinical symptoms, while other types of neurosyphilis often show corresponding symptoms. Cerebrospinal fluid testing is the most important means of diagnosing neurosyphilis, cerebrospinal fluid VDRL is more accurate than RPR, VDRL positive can diagnose neurosyphilis, but VDRL negative can not exclude neurosyphilis, if VDRL negative, according to the cerebrospinal fluid lymphomonocyte ratio increased, also need to consider the possibility of neurosyphilis, for this type of patient regular neurosyphilis treatment can often achieve very good The results are often very good.