What is syphilis?

Syphilis infection is a sexually transmitted infection caused by the bacteria Treponema pallidum.

How common is syphilis?

Nationally, Primary and Secondary (P&S) syphilis rates increased in every age group among those aged 15 years or older and in every race/ethnicity group during 2015-2016. The total number of cases of syphilis (all stages) reported to the CDC increased 17.8% during 2015-2016 (from 74,707 cases to 88,042 cases).2

Most cases of Primary and Secondary Syphilis in 2016 (58%) were associated with men having sex with men (MSM). In 2016, the highest rate of syphilis was found in men ages 20 – 34 years.2

In 2016, the number of congenital syphilis cases was the highest it’s been since 1998.1

Rising rates of syphilis among pregnant women in the United States have increased the number of infants born with congenital syphilis.1 Congenital syphilis has a mortality rate of 50% and there is an 80% risk of infection for untreated mother to fetus.3

How is syphilis spread?

 Syphilis infection can be spread through direct contact with a syphilis sore during vaginal, anal, or oral sex. Syphilis is most commonly sexually transmitted, but sexual penetration or ejaculation does not need to occur for syphilis to spread, because this disease is spread via direct contact with syphilis sores in any location on the body. The bacterium (T. Pallidum) doesn’t stay confined to the area of first contact: it spreads rapidly through the body within hours of initial infection.3An infected pregnant woman can pass the infection to her unborn child during childbirth.

Syphilis can be spread to other people during the primary, secondary, and early latent periods (see below.)

Does syphilis cause symptoms?

Syphilis is also known as the great mimic or the great imitator because in its advanced stages its symptoms can resemble those of many other diseases, making it indistinguishable. The first stage of syphilis is called primary syphilis. During primary syphilis, one or several sores may appear where the infection entered the body. These sores or chancres are usually found on the genitalia, but may be found in other areas that contacted an infected person. The sores are painless ulcers that can heal themselves in 3 to 6 weeks. If the infected person does not realize that they have syphilis and get treated, the infection goes into the second stage of syphilis, called secondary syphilis.

Secondary syphilis occurs during the appearance of ulcers and involves flu-like symptoms and a skin rash. The sores often appear in or around the mouth, vagina, or penis. The rash can be found on hands and soles of feet. Wart patches can also appear in the genital area or skin folds. If the syphilis infection is not treated in this stage, it progresses into a third stage called the early latent period.

In the early latent period, also known as the “hidden stage”, no symptoms may occur, but the infection is still present in the body.

By this time, the infection has spread to many different parts of the body. Without treatment, the syphilis infection may progress to late latent syphilis, also known as tertiary syphilis.

During the tertiary stage, the long term damage of the syphilis infection begins to show. An infected person may begin to notice brain and nerve damage, heart damage, tumors of skin, bones, or liver and other effects throughout the body. The symptoms will depend on what part of the body the syphilis infection has damaged.

Are there any treatments available for syphilis?

Syphilis can be treated effectively with penicillin for all stages. Treatment follow-up is recommended to monitor response to dosage of penicillin.5Damage done to the body before the infection cannot be reversed and reinfection is possible even after successful treatment.6

What complications can result from syphilis?

Syphilis can damage the heart, brain, nerves, eyes, bones, joints, liver, and other organs. It can even cause death. Neurosyphilis, invasion of the central nervous system, can occur 10-20 years after initial infection resulting in difficult muscle movement coordination, paralysis, sensory deficits and dementia. In 2015, there was an increase in reports for ocular syphilis (eye)7, which can lead to permanent blindness.

Women who are infected with syphilis when they are pregnant are at increased risk of miscarriage, stillbirth, prematurity, low birth weight or fatality. Nearly half of all children infected with syphilis while they are in the womb die shortly before or after birth. Infants born to infected mothers who received proper penicillin treatment during pregnancy are at minimal risk for congenital syphilis.8

Does syphilis infection affect the spread of HIV?

When a person has a syphilis infection, they are more likely to acquire HIV from an infected sexual partner. The possibility of clinical relapse after syphilis therapy may be slightly higher in HIV-infected patients.5 There is an estimated 2- to 5-fold increased risk of acquiring HIV if exposed to that infection when syphilis is present.1

In the United States, approximately half of men who have sex with men (MSM) with primary and secondary (P&S) syphilis were also living with HIV.1

Can syphilis infection be prevented?

Yes; syphilis infection can be prevented by refraining from sexual activity until a person is in a lifelong, mutually monogamous relationship with an uninfected partner. Pregnant women should be screened and treated for syphilis infection to prevent the spread of syphilis to their babies.



A syphilis chancre can occur wherever the skin contacted the infection. This man has a chancre on his lip.


Note the chancre on the lower part of the abdomen.


Note the chancre on the inner side of the labia.


This is an example of the rash of secondary syphilis that may occur on the palms and soles of an infected person.

his image shows the “mucous patches” that may occur in the mouth and other mucous membranes during secondary syphilis.


  1. Sexually Transmitted Diseases (STDs).” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 13 Feb. 2017,
  2. 2016 Sexually Transmitted Diseases Surveillance.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 26 Sept. 2017,
  3. Grimes, Jill. “Congenital Syphilis.” Sexually Transmitted Diseases: An Encyclopedia of Diseases, Prevention, Treatment, and Issues, 2:I-Z, ABC-CLIO,LLC, 2014, pp. 627-637.
  4. Centers for Disease Control and Prevention, “Syphilis – CDC Fact Sheet”,, accessed Jan. 2015
  5. “Syphilis.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 17 Aug. 2016,
  6. Schoenstadt, MD Arthur. “Syphilis Treatment.” EMedTV: Health Information Brought To Life, EMedTV,
  7. “Clinical Advisory: Ocular Syphilis in the United States.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 3 Nov. 2016,
  8. “Sexually Transmitted Diseases (STDs).” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 26 Sept. 2017,
  9. “Morbidity and Mortality Weekly Report (MMWR).” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 17 Aug. 2017,



Updated: November 2017