Syphilis is a sexually transmitted disease caused by the pale spirochete. It is known as the “great imitator” because of the similarity of symptoms to many diseases during the various stages of infection. The course of syphilis is usually divided into three stages. The first stage of syphilis occurs when the syphilis spirochete enters the body in 2 to 4 weeks, often with an ulcer in the external genital area, called a hard chancre. It is important to distinguish it from the ulcers formed by soft chancre and genital herpes. The ulcers of stage I syphilis can heal spontaneously without leaving a trace after a few weeks even without treatment, but the syphilis spirochete has quietly entered the blood circulation and spread throughout the body. After 6 to 8 weeks of stage I syphilis, the first thing that easily draws the patient’s attention is the rash on the skin, which is generalized and symmetrically distributed, and can be a rash of spots and papules. In particular, the palms of the hands and the plantar areas of the feet are characterized by a dark red rash, often with peeling skin. At this time, the germ has invaded into various tissues and organs, and is called stage II syphilis. The rash of second-stage syphilis is similar to many skin diseases, such as drug allergic dermatitis, pityriasis rosea, psoriasis, etc., and is prone to misdiagnosis. If left untreated and relying on the patient’s own resistance, the symptoms of second-stage syphilis can disappear naturally, and the syphilis spirochetes are mostly destroyed by the body’s immune system. But some hidden germs, or the body’s immune system is weak, not enough to kill all the germs, syphilis spirochetes can be hidden in the body’s tissues and organs, waiting for the opportunity to move, this relatively quiet period is called latent syphilis (also known as latent syphilis). Although the body is not uncomfortable during this period, a blood test can show that there is “poison” in the blood. When the body’s resistance decreases, the germs will proliferate and become active again, and symptoms will appear, which is called second-stage recurrent syphilis. Phase I syphilis and Phase II syphilis occur within two years of infection and are also called early syphilis. If patients with early syphilis do not receive treatment, then about half of them will develop symptoms of stage III syphilis or late syphilis 5 to 10 years after infection. The lesions of stage III syphilis go deep into various internal organs and are destructive, and can occur in the skin, mucous membranes, bones, heart, blood vessels, nerves, etc. Invasion of the heart leads to syphilitic aortic atresia and syphilitic aortic aneurysm, which can cause heart failure or rupture of aortic aneurysm and death. In the early stage of syphilis, there is a strong contagiousness, and there are a large number of syphilis spirochetes in the ulcer surface of the hard chancre and the skin mucous membrane damage of syphilis rash. In the late stages of syphilis, patients are generally not infectious through sexual contact.