Syphilis is infection caused by bacteria named Treponema pallidum. This disease usually spread by sexual contact. The disease starts as a painless sore, typically on your genitals, rectum, or mouth. Syphilis spreads from person to person via skin or mucous membrane contact with the sores.
After the initial infection, the syphilis bacteria can lie dormant in your body for decades before becoming active again. Early syphilis can be cured, sometimes with a single injection of penicillin. Without treatment, syphilis can severely damage your heart, brain or other organs, and can be life-threatening. As about relation between syphilis and arthritis, syphilis appears not to infect the joints directly except in the most advanced stage of the disease and in congenital syphilis.
To add on, even if you’ve been cured of syphilis, you can become re-infected if you have contact with someone’s syphilis sore.