Syphilis is mainly spread through unprotected sexual contact with someone who is infected. It happens when there is direct contact with a sore caused by the infection, which can appear on the genitals, anus, lips, or inside the mouth.
It can also be transmitted through contact with infected blood or mucous membranes, since the bacteria responsible for syphilis can enter the body this way. Sharing needles, such as during injection drug use, is another possible route of transmission. In pregnancy, a mother can pass the infection to her baby through the placenta or during vaginal delivery.
The infection usually begins with a single, firm sore that may go away on its own after a few weeks, even without treatment. However, the disease can return and progress if it is not properly treated, which is why early evaluation is important. Read more about syphilis symptoms and how they can present.
Using condoms during all sexual activity is the best way to reduce the risk, along with avoiding contact with blood and not sharing needles or unsterilized equipment. If there is any concern about exposure, it is important to see a healthcare provider for testing and treatment guidance.