Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum. The infection progresses through several stages, each with distinct symptoms. The stages are: Primary stage: A painless sore called a chancre appears at the site of the infection, usually within 3 to 4 weeks after exposure. The chancre disappears within 4 to 8 weeks, even without treatment. Secondary stage: A skin rash, fever, and swollen lymph nodes can occur several weeks to months after the appearance of the chancre. Other symptoms can include sore throat, patchy hair loss, weight loss, and muscle aches. Latent stage: After the secondary stage, the infection may become latent, meaning there are no visible symptoms. However, the bacteria are still present in the body and can cause damage to the heart, brain, and other organs if left untreated. Tertiary stage: If left untreated, syphilis can progress to the tertiary stage, which can occur many years after the initial infection. Symptoms can include blindness, deafness, neurological problems, and damage to the heart and blood vessels. It is important to seek treatment for syphilis as soon as possible, as early treatment can cure the infection and prevent long-term damage. Antibiotics, such as penicillin, are effective in treating syphilis.