Syphilis is a disease that often causes fear among the general population. Syphilis is divided into three stages: primary, secondary, and tertiary, with tertiary syphilis being the most infectious stage. Syphilis is a chronic systemic infectious disease caused by the infection of the Treponema pallidum bacterium. It has a wide range of transmission methods, including sexual transmission, blood transmission, and mother-to-child transmission, among others. Therefore, the infectiousness of tertiary syphilis is the strongest, and everyone should pay extra attention and take precautions.