Syphilis is a sexually transmitted infection (STI) caused by the bacterium Treponema pallidum. It has several stages, and if left untreated, it can lead to severe health complications. Here are key points about syphilis: 1. **Transmission:** Syphilis is primarily transmitted through sexual contact, including vaginal, anal, or oral sex. It can also be transmitted from an infected mother to her baby during childbirth (congenital syphilis). 2. **Stages:** Syphilis progresses through several stages: