Syphilis: Causes, risk factors, symptoms, and treatment

Syphilis is a sexually transmitted bacterial infection. It is treatable in the early stages. Without treatment, it can lead to disability, neurological disorders, and death.

It is caused by the bacterium Treponema pallidum (T. pallidum). There are three stages: Primary, secondary, and tertiary.

In 2015, the Centers for Disease Control and Prevention (CDC) noted that 60 percent of cases affect men who have sex with men or with both men and women.

Syphilis is treatable with antibiotics, especially in the early stages. It will not go away without treatment.

Anyone concerned about a possible sexually transmitted infection (STI) should seek medical advice as soon as possible.

Fast facts on syphilis

Here are some key points about syphilis. More detail information is in the main article.

Syphilis is a sexually transmitted infection (STI) that can escalate severely without treatment.

It is spread through sexual contact with sores, known as chancres. Shared contact with surfaces like doorknobs or tables will not spread the infection.

Early treatment with penicillin can cure it.

Syphilis will not come back after treatment, but it can recur with further exposure to the bacteria. Having syphilis once does not prevent a person from contracting it again.

Women can pass syphilis to their unborn child during pregnancy, with potentially disfiguring or fatal consequences.

The infection can lie dormant for up to 30 years before returning as tertiary syphilis.

What is syphilis?

Syphilis is spread by the T. pallidum bacterium.

Syphilis is an infection by the T. pallidum bacteria that is transmitted by direct contact with a syphilitic sore on the skin, and in mucous membranes.

A sore can occur on the vagina, anus, rectum, lips, and mouth.

It is most likely to spread during oral, anal, or vaginal sexual activity. Rarely, it can be passed on through kissing.

The first sign is a painless sore on the genitals, rectum, mouth, or skin surface. Some people do not notice the sore because it doesn’t hurt.

These sores resolve on their own, but the bacteria remain in the body if not treated. The bacteria can remain dormant in the body for decades before returning to damage organs, including the brain.


Syphilis is caused when T. pallidum transfers from one person to another during sexual activity.

It can also be passed from mother to a fetus during pregnancy, or to an infant during delivery. This is called congenital syphilis.

It cannot spread through shared contact with objects like doorknobs and toilet seats.

Syphilis sore
Syphilis is spread through the sores it causes, known as chancres.

Syphilis is categorized by three stages with varied symptoms associated with each stage.

However, in some cases, there can be no symptoms for several years.

Contagious stages include primary, secondary, and, occasionally, the early latent phase.

Tertiary syphilis is not contagious, but it has the most dangerous symptoms.

Primary symptoms

The symptoms of primary syphilis are one or many painless, firm, and round syphilitic sores called chancres. These appear about 3 weeks after exposure.

Chancres disappear within 3 to 6 weeks, but, without treatment, the disease may progress to the next phase.

Secondary symptoms

Secondary syphilis symptoms include:

a non-itchy rash that starts on the trunk and spreads to the entire body, including the palms of the hands and soles of the feet. It may be rough, red, or reddish-brown in color

oral, anal, and genital wart-like sores

muscle aches


sore throat

swollen lymph nodes

patchy hair loss


weight loss


These symptoms can resolve a few weeks after they appear, or they can return several times over a longer period.

Untreated, secondary syphilis can progress to the latent and late stages.

Latent syphilis

The latent phase can last several years. During this time the body will harbor the disease without symptoms.

After this, tertiary syphilis may develop, or the symptoms may never come back. However, the T. pallidum bacteria remain dormant in the body, and there is always a risk of recurrence.

Treatment is still recommended, even if symptoms are not present.

Late or tertiary syphilis

Tertiary syphilis can occur 10 to 30 years after onset of the infection, normally after a period of latency, where there are no symptoms.

Symptoms include:

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