Syphilis is a chronic, systemic sexually transmitted disease caused by the pale spirochete. It can be divided into acquired syphilis and fetal syphilis (congenital syphilis). Acquired syphilis is further divided into early and late syphilis. Early syphilis refers to infection with the syphilis spirochete within 2 years, including stage I, stage II and early recessive syphilis, and stage I and II syphilis can also overlap. Late syphilis has a duration of more than 2 years and includes stage III syphilis, cardiovascular syphilis, and late recessive syphilis. Neurosyphilis can occur in both the early and late stages of syphilis. Fetal syphilis is further divided into early stage (onset within 2 years after birth) and late stage (onset after 2 years of birth). The main routes of transmission are: sexual contact transmission blood transmission mother-to-child transmission. Diagnosis 1. Stage I syphilis: (1) Epidemiological history: history of unsafe sex, multiple sexual partners or sexual partner infection. (2) Clinical manifestations: ①Hard chancre: incubation period is usually 2-4 weeks. It is often single, but can also be multiple. The first nodule is a nodule of corn grain size above the skin surface, and later develops into a round or oval shallow ulcer of about 1~2cm in diameter. The typical nodule is well-defined, with slightly elevated margins and a flat, clean wound; the infiltrate is obvious on palpation and is cartilage-like in hardness; there is no obvious pain or mild tenderness. (2) The lymph nodes in the groin or near the affected area are enlarged unilaterally or bilaterally, painless, isolated from each other and not adherent, of medium quality, not purulent and broken, and the skin on the surface is not red, swollen or hot. (3) Laboratory examination: ①Take the exudate of sclerosing chancre or lymph node puncture fluid by dark-field microscopy or silver-plated microscopy, syphilis spirochetes can be detected, but the detection rate is low; ②Serological test for non-syphilis spirochetes is positive. If the infection is less than 2 to 3 weeks, the test may be negative and should be rechecked after 4 weeks of infection. (4) Diagnostic classification: ① suspected cases: should meet both the clinical manifestations and laboratory tests in ②, may or may not have epidemiological history; or meet both the clinical manifestations and laboratory tests in ③, may or may not have epidemiological history; ② confirmed cases: should meet both the requirements of suspected cases and laboratory tests in ①, or meet both the requirements of suspected cases and both types of syphilis serological test is positive. Second, the treatment 1, general principles: ① early detection, timely formal treatment, the earlier the treatment effect is better; ② sufficient dose, the course of treatment rules. Irregular treatment may increase recurrence and promote the early occurrence of late damage; ③After treatment, we should follow up for a sufficient period of time; ④Screening and treatment of all sexual partners at the same time. 2, treatment plan: (1) early syphilis (including stage 1, stage 2 and latent syphilis < 2 years) recommended plan: procaine penicillin G 800,000 U / d, intramuscular injection, for 15 d; or benzathine penicillin 2.4 million U, divided into bilateral gluteal intramuscular injection, once a week, a total of 2 times. Alternative regimen: Ceftriaxone 0.5-1g, once daily, intramuscularly or intravenously for 10 d. For allergy to penicillin use the following drug: Tetracycline 100mg, twice daily.