Syphilis is a sexually transmitted infection (STI) caused by the bacterium Treponema pallidum. It progresses in stages, each with its own symptoms and characteristics. There are four stages of syphilis:

1. Primary syphilis: This is the first stage of syphilis, occurring about 3-4 weeks after exposure to the bacteria. The primary symptom is the appearance of a painless sore called a chancre at the site of infection (genital area, anus, mouth, or other areas). The chancre is usually firm, round, and small, and it heals on its own within a few weeks.
2. Secondary syphilis: If the primary stage is not treated, the infection progresses to the secondary stage, which typically occurs 2-10 weeks after the chancre appears. Symptoms of secondary syphilis include skin rash (often on the palms of the hands and soles of the feet), mucous membrane lesions, fever, swollen lymph nodes, sore throat, patchy hair loss, headaches, weight loss, muscle aches, and fatigue. These symptoms may come and go over the course of a few weeks or months.
3. Latent syphilis: After the secondary stage, syphilis enters a latent (hidden) stage where there are no visible symptoms, but the bacteria remain in the body. Latent syphilis is divided into early latent (less than one year since secondary syphilis) and late latent (more than one year since secondary syphilis) stages.
4. Tertiary syphilis: In some cases, syphilis can progress to the tertiary stage, which can occur years or even decades after the initial infection. Tertiary syphilis can cause severe complications such as damage to the heart, brain, nerves, eyes, liver, bones, and joints. This stage can be life-threatening.

It’s important to note that not everyone with syphilis will progress to the tertiary stage, and the infection can be effectively treated with antibiotics, especially in the early stages. Regular testing and early treatment by your healthcare provider are crucial to prevent complications and reduce the risk of transmitting the infection to others.