Transmission occurs most frequently by sexual contact.
Syphilis can also be transferred to the fetus via the placenta after the 10th week of pregnancy. Syphilis has 3 stages. In the primary stage, painless sores, called chancres , appear 10 days to 6 weeks after exposure which can disappear on their own. The secondary stage can begin a week to 6 months after the primary stage. A skin rash is the hallmark of this stage, and lesions may appear again.