A sexually transmitted or congenital infection caused by the bacterium Treponema pallidum.
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.