Syphilis is not usually transmitted through saliva, but mainly through mother-to-child, sexual contact and blood. Syphilis is a sexually transmitted disease (STD) caused by the spirochete syphilis, and is mainly transmitted from mother to child, through sexual contact, and through blood. Syphilis cannot be transmitted through saliva because the level of spirochetes in saliva is low and usually does not meet the criteria for transmission, but if there is an ulcer in the mouth and blood is present in the saliva, it is still possible to transmit the disease through blood-tinged saliva. Syphilis generally can not be transmitted through saliva, if the patient has a history of close contact with syphilis patients, should promptly consult a doctor, and actively improve the relevant examination, a clear diagnosis, so as not to delay the condition.