Syphilis - including symptoms, treatment and prevention

Syphilis is a bacterial infection caused by Treponema pallidum.

Syphilis and congenital syphilis are notifiable conditions1

How syphilis is spread

Almost all cases occur as sexually transmitted infections (STIs), though an infected pregnant woman can infect her baby in the uterus or during vaginal delivery. Some babies with congenital syphilis are stillborn and others may have severe deformities.

Signs and symptoms of syphilis

Syphilis acquired as an adult may occur in three stages: 

Primary stage

A primary stage in which a hard, usually painless, ulcer called a chancre develops at the site of infection, usually on the genitals. Untreated, the primary chancre usually goes away within 4 weeks. There is often painless swelling of lymph glands during this stage. The chancre may be inside the vagina in women, or inside of the mouth or anus, depending on how the infection was acquired. The person may not know they have the infection.

Secondary stage

A secondary stage occurs 2 to 4 months after infection, lasts several weeks and often comes back in the following 2 years. The most common feature is a flat, red rash over the whole body. Syphilis is one of the few causes of this sort of rash on the palms and soles. Many other symptoms commonly occur and almost any part of the body may be involved.

After this secondary stage a prolonged latent period frequently occurs. A latent period is a time during which there are no symptoms or obvious signs of disease.

Tertiary stage

A tertiary (third) stage may occur in up to 30% of untreated individuals after a latent period which may be many years. In some cases the disease may involve the brain and spinal cord (neurosyphilis), or the heart and blood vessels (cardiovascular syphilis), producing severe complications, disability and even death.

Diagnosis of syphilis

Diagnosis of syphilis can be made during the primary stage by microscopic examination of a scraping from the base of the chancre, though this test is not commonly performed. Later, diagnosis is made by blood tests.

Syphilis involving the brain and spinal cord is confirmed by testing of CSF (cerebrospinal fluid: the fluid surrounding the brain and spinal cord).

Incubation period

(time between becoming infected and developing symptoms)

9 to 90 days, with an average of 3 weeks from contact to the development of a chancre.

Infectious period

(time during which an infected person can infect others)

During primary and secondary stages and possibly the first 2 years of the latent period. A person is no longer infectious 24 to 48 hours after starting appropriate antibiotic treatment.

Treatment for syphilis

Effective antibiotic treatment is available. Treatment needs to be supervised carefully and long-term follow-up is required, particularly for patients with late stage syphilis infection.

Treatment of the mother during pregnancy may be sufficient to prevent fetal infection. Sometimes babies require an additional course of antibiotics after birth.

Prevention of syphilis

  • People with syphilis should refrain from any sexual contact for at least 1 week after completing treatment or until the lesions of early syphilis (if they were present) are fully healed
  • people with syphilis should also refrain from any sexual contact until sexual partners have been contacted, tested, if indicated treated
  • follow-up blood tests must be done to make sure that treatment has cleared the infection
  • pregnant women are screened for syphilis in early pregnancy and again in late pregnancy if they are at increased risk of acquiring syphilis
  • testing to exclude other sexually transmitted infections is advisable.

Useful links

1 – In South Australia the law requires doctors and laboratories to report some infections or diseases to SA Health. These infections or diseases are commonly referred to as 'notifiable conditions'.

Also in this section