The spirochetes are present in the saliva of a person with syphilis, so it is possible to transmit syphilis through saliva, but the probability is low. Syphilis is a disease caused by the syphilis spirochete, which is contagious and is mainly transmitted through sexual contact, mother-to-child and blood. Patients with syphilis are the source of syphilis, and their skin lesions, blood, semen, and saliva all carry the syphilis spirochete, so syphilis may be transmitted through saliva, but the probability is low. If there are ulcers and wounds in the mouth, it is possible to be infected with syphilis by kissing a person with syphilis. If the oral mucosa is not broken, or just eat with a syphilitic patient at the same table, usually will not be infected by syphilis from the saliva of the syphilitic patient. It is recommended to adopt good living habits and avoid high-risk sex. If syphilis is diagnosed, it should be treated promptly.