Syphilis is a sexually transmitted infection (STI) caused by the bacterium Treponema pallidum. It spreads from person-to-person by direct contact with a syphilitic sore, known as a chancre, which can occur in, on, or around the penis, vagina, anus, rectum, and lips or mouth. Syphilis can spread during vaginal, anal, or oral sex, and pregnant people with syphilis can transmit the infection to their unborn child.

The disease develops in stages, including primary, secondary, latent, and tertiary, and each stage can have different signs and symptoms. During the first (primary) stage of syphilis, a single sore or multiple sores may appear in, on, or around the penis, vagina, anus, rectum, and lips or in the mouth. In the second stage, a rough, red or brown rash develops, which can eventually cover the entire body, including the bottom of the feet and palms.

Syphilis can cause serious health problems without treatment, including damage throughout the body, problems during pregnancy, and increased risk of HIV infection. However, when diagnosed and treated in its early stages, syphilis is easy to cure with antibiotics, such as penicillin.

To prevent syphilis and other STIs, it is recommended to abstain from sex. If sexually active, using a condom during vaginal, anal, or oral sex can reduce the risk of infection. It is also recommended to get tested regularly for syphilis and other STIs if sexually active and to have an honest and open talk with a healthcare provider.