Secondary syphilis is a stage of the sexually transmitted infection syphilis, which occurs after the initial infection. It typically appears weeks to months after the primary stage and is characterized by a rash, often on the trunk and extremities, and flu-like symptoms. This stage indicates that the bacteria, Treponema pallidum, has spread throughout the body. If left untreated, secondary syphilis can lead to more severe health issues. The rash may resolve on its own, but the infection remains in the body. Early diagnosis and treatment with antibiotics, usually penicillin, are essential to prevent complications and further transmission.