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How can you tell if a man has syphilis?

Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum. It has often been called “the great imitator” because so many of the signs and symptoms are indistinguishable from those of other diseases. The infection has three stages, each with its own set of symptoms. Without treatment, syphilis can damage the heart, aorta, brain, eyes, and bones over time.

What are the symptoms of syphilis?

There are three stages of syphilis, each with different symptoms:

Primary syphilis

The first sign of infection is a small sore, called a chancre. The sore appears at the spot where the bacteria entered the body. While most people infected with syphilis develop only one chancre, some develop several. The chancre usually develops about 3 weeks after exposure, but can range from 10 to 90 days. A chancre is usually firm, round, and painless. It lasts 3 to 6 weeks and heals without treatment. However, the underlying disease still remains and may reappear in the second (secondary) or third (tertiary) stage.

Secondary syphilis

Secondary syphilis occurs 2 to 10 weeks after the chancre appears. At this stage, people may have:

  • Mucous membrane lesions in the mouth, vagina, or anus
  • Skin rash, often on the palms of the hands and soles of the feet
  • Condyloma lata (moist, flat, whitish or gray growths in warm, moist areas including the mouth, underarm, and groin)
  • Patchy hair loss
  • Latent syphilis, with no visible symptoms

Without treatment, symptoms disappear, and the person enters a latent phase. The latent phase can last for years.

Late (tertiary) syphilis

About 20% to 30% of people with untreated syphilis develop late-stage complications. This can happen 10 to 20 years after the initial infection. At this point, the infection may damage the heart, eyes, brain, nervous system, bones, joints, and other parts of the body. Symptoms include:

  • Difficulty coordinating muscle movements
  • Paralysis
  • Numbness
  • Gradual blindness
  • Dementia

In the late stages, syphilis can lead to death.

How is syphilis spread?

Syphilis spreads from person to person through direct contact with syphilis sores. Sores mainly occur on the external genitals, vagina, anus, or in the rectum. Sores also can occur on the lips and in the mouth.

Transmission occurs during vaginal, anal, or oral sex. Pregnant women with the disease can pass it to their unborn children.

Syphilis cannot be spread through contact with toilet seats, door knobs, swimming pools, hot tubs, bath tubs, shared clothing, or eating utensils.

Who is most at risk?

Men who have sex with men are most at risk. About 53% of new syphilis cases occur in this group. Heterosexual people account for about 15% of new cases. The rate of syphilis is also higher in HIV-infected persons. The infection is most common in developing nations among men age 15 to 49.

How do doctors diagnose syphilis?

Doctors use several tests to diagnose syphilis:

Blood tests

Blood tests are the most common way to screen for syphilis. Two screening tests are used. The first, known as the VDRL or RPR test, looks for antibodies made by the body when infected with syphilis. The second screening test, called the FTA-ABS, measures antibodies made specifically against the syphilis bacteria. If the results of the initial screening tests are abnormal, doctors will run a confirmatory blood test called the TP-PA (or T. pallidum particle agglutination assay).

Microscope examination

Doctors may examine fluid from a chancre under a microscope. This allows them to see the syphilis bacteria directly and confirm a diagnosis.

Brain imaging

An MRI or CT scan of the brain may reveal syphilis has infected the nervous system.

Spinal tap

A spinal tap (also called a lumbar puncture) helps doctors look for signs of syphilis in the fluid that surrounds the brain and spinal cord.

How is syphilis treated?

Syphilis is easy to cure in its early stages. Penicillin, an antibiotic, injected into a muscle, is the preferred treatment for syphilis. Penicillin is the only known effective antibiotic for treating syphilis in all stages. Alternatives for patients allergic to penicillin include:

  • Doxycycline
  • Tetracycline
  • Ceftriaxone

Treatment will kill the syphilis bacterium and prevent further damage, but it will not repair any damage already done. For that reason, doctors recommend prompt treatment. Treatment usually involves:

  • One injection of penicillin for primary, secondary, or early latent syphilis
  • Weekly injections of penicillin for late latent syphilis or infections of more than one year’s duration
  • Daily oral antibiotics for patients with neurosyphilis

Patients with late-stage syphilis may need to repeat doses every 1 to 3 weeks. Treatment usually lasts 10 to 14 days. Even after treatment, blood tests may remain positive for syphilis for about 1 year.

What complications can occur?

Untreated syphilis can cause severe health problems. Complications include:

  • Damage to the aorta, heart valves, and brain
  • Blindness or deafness
  • Meningitis and stroke
  • Stillbirth or newborn death
  • Bone damage

How can syphilis be prevented?

There are several ways to avoid syphilis infection:

  • Abstain from sex or limit sex to one uninfected partner
  • Use condoms consistently and correctly during any type of sex
  • Get regular syphilis screenings if you are sexually active or pregnant
  • Ask partners to get screened and treated


Syphilis is a bacterial infection spread through oral, vaginal, and anal sex. The disease progresses in stages if untreated. Syphilis starts with painless sores at the site of infection. Later, it causes rashes and lesions throughout the body. Without treatment, syphilis damages the heart, brain, eyes, and other organs. Screening blood tests can diagnose syphilis in its early stages. Penicillin injections can cure the disease before complications develop. Using condoms, limiting sex partners, and screening can help prevent syphilis infection.