Syphilis is a sexually transmitted communicable disease. The infection progresses in several stages and often remains undetected. It is highly treatable if discovered early. This article provides an overview about the cause, diagnosis, prevention and treatment of syphilis.

At a glance

  • Syphilis, also called lues, is a sexually transmitted communicable disease.
  • Syphilis is caused by the bacterium Treponema pallidum, which only occurs in humans.
  • An untreated syphilis infection has a three-stage progression.
  • If the infection is detected early, it can be easily treated with antibiotics.
  • If the infection is detected late, it can permanently damage the organs.
  • Condoms, femidoms and dental dams can protect against transmission.

Note: The information in this article cannot and should not replace a medical consultation and must not be used for self-diagnosis or treatment.

Syphilis: man sitting on a couch with his hands forming a diamond shape. A doctor is sitting obliquely opposite him holding a clipboard and ballpoint pen in his hands.

What is syphilis?

Syphilis is also called venereal syphilis, Lues venerea or chancre. It is a globally prevalent sexually transmitted disease.

If syphilis is not treated, it can progress in three stages, but also heal spontaneously. There are sometimes no symptoms at all between the stages. The symptoms can be very mild and not all people notice when they have been infected with syphilis. Those affected can thus spread the pathogens unnoticed.

In Germany, syphilis currently occurs predominantly in men who have sex with men. Among other things, the reason is that homosexual men in Germany have used condoms less often since there have been drugs to prevent an HIV infection

Syphilis can be transmitted by sexual contact, minor wounds or from pregnant women to fetus.

The treponema bacteria can be transmitted the following ways: 

  • by direct sexual contact, intense mucosal contacts 
  • small wounds in the skin or mucous membranes 
  • via the womb to the unborn child of an infected pregnant woman (congenital syphilis)

The pathogens can also be transmitted via blood transfusions. But due to systematic testing of blood donations, this practically no longer occurs. 

What are the indications of syphilis?

Only about half the patients with syphilis show symptoms of the disease. If it remains untreated, it can progress in three stages with various symptoms, but also heal spontaneously.  

First stage (Lues I, primary syphilis) 

To begin with, a small lump develops where the bacteria invade the body. This is usually on the penis or labia, but also in the area of the mouth or anus, depending on sexual practice. The nearby lymph nodes swell up and the lump develops into a hard ulcer. The ulcers on the genitals are not painful. The first stage heals by itself after 4 to 6 weeks. 

Second stage (Lues II, secondary syphilis) 

The bacteria spread in the entire body and the following symptoms can occur with varying severity: 

  • fever 
  • headaches, joint pain or muscle aches 
  • swelling of many lymph nodes 
  • moth-eaten alopecia (hair loss) 
  • skin rashes: from blotches to small lumps, later scaly, in rare cases there may be small skin sores and similar changes to the mucous membranes 
  • additional callus formation on the palms and soles of the feet 
  • neurological consequences such as meningitis and visual and hearing disorders 

This stage can last for several years and the symptoms may flare up repeatedly.  

Important: The one-year period from the time of infection is called early syphilis. In stage 1 and 2 of syphilis, patients are contagious to others, especially in the first stage. All sexual partners of the last three months (in the first stage) and the last twelve months (in the second stage) should therefore be advised about a possible infection. After that, the disease may be without symptoms for several years (latent syphilis). There is also a risk of infection in the early stage of this latency. In the subsequent stages (late syphilis), infected people are no longer contagious.  

Third stage (Lues III, tertiary syphilis) 

In this phase, the following symptoms can appear with varying severity: 

  • lumps on the skin 
  • nodal sores (gummas or gummata) on the skin and internal organs 
  • vascular changes to the aorta, bulging vessels (aneurysms) that can rupture 
  • neurological consequences: meningitis, infection of peripheral nerves, cranial nerves, the spinal cord and the brain  

Neurological symptoms of the third stage of syphilis can be: 

  • pain and numbness in the lower abdomen and legs (Tabes dorsalis) 
  • palsies and sensory disturbances 
  • speech disorders (aphasia) 
  • seizures 
  • altered pupillary reaction to light  
  • mental symptoms such as confusion, mood swings, thought disorders, hallucinations, delirium or coma 

If this final stage is not treated either, the progressive palsies result in death after about 4 to 5 years. In principle, syphilis can heal at any stage, but the resulting organ damage cannot be repaired. 

Important: Because syphilis is highly treatable nowadays, stage 3 (tertiary syphilis) has become very rare. However, early neurosyphilis occurs more frequently in HIV-positive patients and the progression of the disease can be more severe overall.

What causes syphilis?

The cause of syphilis is the bacterium Treponema pallidum. It is globally prevalent and only occurs in humans.

Having unprotected sex and frequently changing partners increases the risk of being infected with syphilis.

Would you like to calculate your risk of syphilis and other sexually transmitted infections (STIs)? WIR – Walk In Ruhr, Zentrum für Sexuelle Gesundheit und Medizin (Center for Sexual Health and Medicine) offers an online STI risk test.

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How common is syphilis?

Around 8,000 people catch syphilis every year in Germany.

The number of reported cases of syphilis has increased continuously since 2010. In Germany, around 8,000 people currently catch syphilis every year. 

About 12 million people are affected around the world, 90% of whom are in developing countries.

How does a syphilis illness progress?

The progression of syphilis is in stages. A spontaneous recovery is absolutely possible. If the infection is detected early, it can be easily treated with antibiotics. But if left untreated, the disease occasionally causes very severe disabilities and can even be fatal.

How can syphilis be prevented?

A syphilis infection can be prevented with safe sex. Condoms, femidoms and dental dams can all protect against an infection. Using them consistently and correctly is important. Syphilis can also be transmitted mouth-to-mouth and from the mouth to the genitals or anus. People with a verified syphilis illness should refrain from all sexual contact until the end of their treatment. 

Important: Anyone noticing suspicious changes on their skin or mucous membranes, or those of their partner, should not hesitate to talk to a doctor. A syphilis treatment is simple and effective, and reduces the further spread of the disease.

How is syphilis diagnosed?

If syphilis is suspected, doctors can take swabs of the affected sites and examine them under a special microscope or with specific laboratory tests. The bacteria can be detected directly in a lab. A positive pathogen detection should always lead to a treatment.  

Laboratories can detect various antibodies in blood samples. There are antibodies with which it is possible to detect contact with syphilis pathogens and antibodies with which the activity of the disease can be determined. With these antibody tests, doctors can decide whether patients must be treated and later whether the therapy was successful. 

To diagnose neurosyphilis, doctors must take spinal fluid from those affected and test this for antibodies. 

Results of rapid syphilis tests are not as reliable as lab tests. But they can be used as screening procedures and give an indication of an infection. Further antibody tests must then be carried out for accurate diagnostic confirmation.  

Important: Clinical signs of early syphilis appear from about 3 weeks after infection. If syphilis is suspected, sexual partners should also be tested for a possible infection.   

How is syphilis treated?

Syphilis is caused by bacteria. The disease can therefore be easily treated with antibiotics. As a general rule, penicillin is used in all stages of the disease. Depending on its stage, syphilis is treated with 1 to 3 depot injections into the gluteal muscle at weekly intervals. For neurosyphilis, an intravenous therapy over 2 to 3 weeks is required. Regular antibody tests verify the therapy success. 

If the bacteria decay too quickly as a result of penicillin therapy, the pathogens’ toxic ingredients may cause severe immune system reactions. Symptoms like shivering, fever and headaches then occur. To relieve these symptoms, doctors often additionally administer cortisone, with one dose immediately before therapy is initiated.  

After the end of the therapy, a quarterly check-up is performed in which doctors check the extent to which the clinical symptoms have eased and that the number of specific antibodies in the patient’s blood has decreased. 

With early syphilis, the symptoms usually recede quickly after therapy. Sufferers should avoid sexual contact until full recovery. With late syphilis, permanent impairments may develop due to organ damage. 

What other useful information is there?

Syphilis is a notifiable disease. The report is made anonymously through a laboratory and by the doctor treating it.  

Points of contact for syphilis 

Liebesleben is the website of the Federal Center for Health Education (BZgA). You can find information about love, sex and protection there.

WIR – Walk in Ruhr, Zentrum für Sexuelle Gesundheit und Medizin (Center for Sexual Health and Medicine) also provides useful information on syphilis and other sexually transmitted diseases.

Reviewed by the Deutsche STI-Gesellschaft.

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