Causes

The cause of syphilis is a bacterium called Treponema pallidum. The most common way syphilis is spread is through contact with an infected person's sore during sexual activity. The bacteria enter the body through minor cuts or abrasions in the skin or mucous membranes. Syphilis is contagious during its primary and secondary stages, and sometimes in the early latent period.

Less commonly, syphilis may spread through direct contact with an active lesion, such as during kissing. It can also be passed from mothers to their babies during pregnancy or childbirth.

Syphilis can't be spread by using the same toilet, bathtub, clothing or eating utensils, or from doorknobs, swimming pools or hot tubs.

Once cured, syphilis doesn't return on its own. However, you can become reinfected if you have contact with someone's syphilis sore.