Health A-Z

Medical Content Created by the Faculty of the
Harvard Medical School

Syphilis

What Is It?

Syphilis is a sexually transmitted disease (STD) caused by a type of bacteria called Treponema pallidum. In its earliest stage, syphilis produces an open sore (ulcer) that leaks fluid filled with syphilis bacteria. Syphilis can be transmitted by contact with this ulcer or other infectious sores that form later in the disease, usually during vaginal, oral or anal sex. If untreated, syphilis moves through a series of stages that affect different parts of the body, although the stages can overlap:

• Primary syphilis — In this first stage, syphilis causes a painless ulcer called a chancre, usually in the genital area where syphilis bacteria enter the body. This stage begins 10 to 90 days (average three weeks) after a person has been exposed to someone with syphilis. The sore goes away without treatment in about four to eight weeks.

• Secondary syphilis — In this stage, syphilis bacteria spread throughout the body. This usually causes a rash over most of the body along with fever, aches and pains, and other symptoms. This stage begins six to eight weeks after a person is exposed to syphilis, and it lasts up to one year.

• Latent syphilis — This stage begins when the secondary stage ends. Although there are no symptoms, the person remains infected. This stage can last for many years, even for the rest of a person's life. About one-third of cases of latent syphilis progress to tertiary syphilis.

• Tertiary syphilis — In this stage, syphilis bacteria can cause severe damage to many different internal organs, including the brain and spinal cord. It usually begins within 10 years of infection and can end in death.

Pregnant women with syphilis can pass the bacteria to their babies, causing a condition known as congenital syphilis. Congenital syphilis causes a variety of skin and organ problems in infants, and it can be deadly. Pregnant women with syphilis also have about a 40% chance of having a baby that is stillborn.

If you are infected with syphilis, it may be easier for you to become infected with HIV. If you already have HIV, a syphilis infection may make you more likely to spread HIV to others.