Syphilis

What is it?

Syphilis is a sexually transmitted infection (STI) caused by the bacterium Treponema pallidum. The disease only occurs in humans. Millions of people worldwide contract the disease every year.

In developing countries, congenital syphilis is a major cause of infant mortality.

Symptoms

There are different stages of the disease:

• A painless ulcer at the site of the first infection, e.g. on the genitals or near the mouth, a few weeks after contact. Usually a painless swelling of the surrounding lymph nodes also occurs. The ulcer disappears spontaneously after 4-6 weeks
• A stage with non-itchy skin abnormalities (the soles of the feet and palms of the hands are often affected), a flu-like sensation (fever, headache, sore throat, muscle pain, malaise) and other abnormalities, a few months later. At this stage, the disease is highly contagious.
• During the third stage (many years after infection), the central nervous system is affected with severe neurological and psychiatric symptoms. Eventually, the third stage can result in cardiovascular syphilis, affecting the heart and the large blood vessels.

By no means does everyone who goes through the first stage proceed to the second or third stage. Between stage two and three, there is an interval of several years in which there are no signs of disease, but the blood tests are positive for syphilis.

How is the diagnosis determined?

The disease can take many forms, often resembling other diseases. Moreover, the disease is rare in Western Europe today. For both these reasons, the diagnosis is sometimes missed.

A positive diagnosis can be obtained with a blood test that detects antibodies against the bacteria. The bacteria can also be diagnosed in the fluid from an ulcer.

Additional difficulty: given the incubation period of three months, after a first negative result it cannot be completely excluded that there is no syphilis infection. Certainty can only be obtained after a second negative control test three months later.

Treatment

In the early stages, syphilis is easy to treat with repeated injections of antibiotics (Penicillin G).

Latest publication date: 12/12/2023
Supervising author: Dr Ameye Filip