Syphilis is a chronic, systemic sexually transmitted disease caused by the syphilis spirochete. The main causes of syphilis in men are as follows:1. Sexual contact transmission, which is the most important way of transmission of the syphilis spirochete, and more than 95% of syphilis infections are transmitted through risky or unprotected sexual behavior.2. Blood transmission, which is contracted through blood transfusions, contaminated needles, surgical instruments, etc.3. Indirect infection, which is usually due to contact with syphilis patient’s secretion and utensils contaminated by secretion The infection is usually spread through contact with the secretions of the patient and the utensils contaminated by the secretions, such as clothes, towels, bedsheets and razors.