Syphilis is one of the most common sexually transmitted infections (STIs). Over 74,000 new cases were reported in the United States in 2015. The majority of cases in 2015 were found in gay, bisexual, and other men who have male sexual partners.  The bacterium Treponema pallidum is what causes the infection, and is passed from person to person through sexual contact: oral, vaginal, or anal intercourse.

It does have a cure, but if the disease progresses far enough, the treatment cannot reverse or heal tissue or organ damage already caused by the infection. To learn about syphilis and pregnancy, view our article Syphilis During Pregnancy.

Syphilis: Transmission & Symptoms

How is it transmitted?

Syphilis is transmitted through skin-to-skin contact during intercourse, whether oral, vaginal, or anal. Because it can be passed to a sexual partner from bacteria present on the skin, a condom cannot completely protect against transmission.

What are the symptoms?

Syphilis infection has four different stages that each present different symptoms. The first symptoms will present anywhere from 10 to 90 days after initial infection (the average is 21 days).

  • Primary syphilis:  the development of one or multiple papules which develops into a clean, painless ulcer (similar to a chancre sore), usually located on the genitals. The sore will often heal four to six weeks after appearing.
  • Secondary syphilis:  starting two to ten weeks after the sore heals (or sometimes during its healing process), you may experience a rash, which can cover the whole body (red or brownish rough spots); sores in the mouth, vagina, or anus; grayish or white wart-like growths; fever; swollen lymph nodes; headaches; weight loss; and/or a sore throat and other flu-like symptoms, like fatigue.
  • Latent syphilis:  1-2 months after the onset of secondary syphilis, the symptoms may disappear for several years.
  • Late-stage or tertiary syphilis:  you may experience neurological and cardiovascular issues, along with problems with other organs. Symptoms depend on the organ affected.
  • Neurosyphilis and Ocular syphilis:  these can become issues during any stage of infection if the bacteria reaches the nervous system or the eyes, respectively. Possible symptoms of neurosyphilis:  headaches, movement or coordination issues, changes in behavior, paralysis, dementia, and/or sensory issues. Possible symptoms of ocular syphilis:  vision changes, a decrease in visual range, and/or blindness.

How can I get tested?

If you suspect that you may have syphilis, it is important to get tested. The test that is typically used is a serological test that checks for the presence of antibodies in your blood. Initially, one of the two tests is used to check for the presence of antibodies for syphilis-like infections, called nontreponemal testing:

  • RPR (Rapid Plasma Reagen) – A good screening test which can also be used to monitor the level of infection after treatment has begun.
  • VDLR (Venereal Disease Research Laboratory) – Uses a blood sample or a sample of CSF (cerebral spinal fluid), and is mostly used to diagnose neurosyphilis.

To confirm initial screens like the RPR test, treponemal testing can be done to specifically target syphilis-only antibodies:

  • FTA-ABS (fluorescent treponemal antibody absorption) – Typically used for the first 3-4 weeks post-exposure. Uses a blood or CSF sample to identify specific syphilis bacterium antibodies and diagnose syphilis (or neurosyphilis).
  • TP-PA (T. pallidum particle agglutination assay) – More specific and has less false positives than FTA-ABS.
  • MHA-TP (microhemagglutination assay) – Another test to confirm a syphilis diagnosis, but is less commonly used now.
  • Immunoassays (IA) – Automated tests that make screening specifically for syphilis easy.

Though much less commonly used, there are two tests available that can detect the presence of the bacteria (not just the antibodies):

  • Dark-field microscopy – When syphilis is first suspected, a scraping of the chancre can be placed on a slide and viewed using a specific type of microscope.
  • PCR (polymerase chain reaction) – Using a sample of blood, CSF, or of the sore itself, PCR can specifically detect genetic material (DNA) from the bacteria.

Based on the results, you and your primary healthcare provider can take the necessary steps to clear the infection from your body.

The US Preventative Services Task Force (USPTF) now recommends that ALL pregnant women are screened for syphilis.

What treatment options are available?

The good news is that it is easily treated with antibiotics. Penicillin G is the only effective treatment, meaning that those persons with a penicillin allergy may not have a suitable alternative treatment. Talk to your doctor if this applies to you.
Treatment with penicillin G will rid your body of the infection, but cannot undo organ/tissue damage that has already occurred. Most often, diagnoses are made in the primary or secondary stages before most tissue or organ damage occurs unless the disease has already moved to ocular or neurosyphilis.

Can it be prevented?

Like most STIs, the only two 100% ways to avoid contracting it are (1) to abstain from any and all sexual activity, and (2) to be in a monogamous relationship where each partner has only had intercourse with the other, and neither are currently infected with any STIs.

The consistent and correct use of condoms is always suggested with oral, vaginal, and anal sex. However, since the bacteria which cause syphilis can be present on the skin not protected by a condom, usage does not significantly reduce your chances of transmitting or picking up the disease.

Compiled using information from the following sources:

1. Harms, R. W. (2004). Mayo Clinic guide to a healthy pregnancy. New York: HarperResource.

2. Kliegman, R. (2007). Nelson textbook of pediatrics (18th ed.). Philadelphia: Saunders.

3. M.D., R. J. (1994). Lifestyle During Pregnancy. Mayo Clinic Complete Book of Pregnancy and Baby’s First Year. New York: William Morrow and Company Inc.

4. Centers for Disease Control and Prevention (CDC).

5. Mayo Clinic.

6. AACC, Lab Tests Online