Syphilis: Understanding the Late-Stage Effects of Untreated Infection

The correct answer would be Syphilis. Syphilis is a type of bacterial sexually transmitted infection caused by the bacterium Treponema pallidum. If untreated, syphilis progresses through four stages, and the final stage, known as tertiary syphilis, can manifest several years after the initial infection and may affect vital organs such as the heart, brain, and nervous system.