Treponema pallidum is a type of bacterium that causes the sexually transmitted infection known as syphilis. It is a spiral-shaped organism that can only survive in human hosts. The bacterium is transmitted through direct contact with syphilis sores during sexual activity, and it can also be passed from an infected mother to her baby during pregnancy. Once inside the body, Treponema pallidum can lead to various stages of syphilis, each with different symptoms. Early symptoms may include sores and rashes, while untreated infections can progress to more severe health issues, affecting the heart, brain, and other organs. Early diagnosis and treatment with antibiotics are crucial for effective management.