Syphilis : Swiss AIDS Federation


Syphilis is caused by the bacterium Treponema pallidum and can progress chronically. Left untreated, syphilis leads to serious health complications.

How is syphilis transmitted?

Syphilis can be transmitted through oral, vaginal or anal intercourse with an infected person in a contagious phase.

During pregnancy, transmission from mother to child is possible. Without treatment, the consequences for the child are serious.

What are its symptoms and its consequences?

Left untreated, syphilis manifests in different stages.

  • The first symptoms can appear as early as one week and as late as three months after infection, for example as lumps, sores or lesions of the mucous membrane at the entry point of the bacterium. Sores in the area of the anus, vagina or throat often remain undiscovered because they are painless. These symptoms disappear, even without treatment, after four to six weeks. However, the disease and its transmissibility remain.
  • The second stage follows within several weeks and is characterised by mainly non-itching skin rashes, which often affect the palms of the hands and the soles of the feet. Swollen lymph nodes, hair loss and other symptoms may also occur. These symptoms likewise disappear on their own, without treatment.
  • Next is a period of several months to several years during which the disease progresses without the appearance of symptoms. During the first year of this stage, those affected may show sporadic damage of the skin and mucous membranes and consequently are potentially still infectious.
  • In the long term, syphilis can lead to severe damage to the heart, brain, bones, skin and other organs.

All stages can lead to damage of the nervous system, which is referred to as neurosyphilis.

How is syphilis tested for?

A syphilis infection is usually diagnosed with a blood test. Rapid tests are available as well, but the Federal Office of Public Health (FOPH) does not recommend them. At the early stage, the pathogen can be detected through a swab of the injured mucosa as well.

How is syphilis treated?

Syphilis is treated with antibiotics. If recognised early, the infection is curable.

Should sexual partners get treatment as well?

The person concerned should consider, together with her or his doctor, where the infection came from and whom it might already have been passed on to. Those sexual partners should be informed about the diagnosis, so they can, if necessary, get treatment.

Current sexual partners need to be treated simultaneously to avoid a “ping-pong effect”, whereby partners repeatedly re-infect each other. An additional benefit is the fact that condom use can be dispensed with during simultaneous treatment.

Note: The incubation period can last up to three months, which means that a lab test may not show an infection for the first three months. For that reason alone, prompt treatment of sexual partners, regardless of their test result, is important.

Non-treatment may eventually lead to severe health problems.

How can the (re)infection be prevented?

Condoms reduce the risk of getting infected with syphilis. But an infection is possible despite condom use. It is important to detect and treat an infection early.

If you have changing or multiple sexual partners during the same time period, talk to your doctor or another specialist about sexually transmitted infections (including HIV) and get advice on whether tests may be necessary.

In case of an infection, provides tips on how to inform your partner.

Source: Federal Office of Public Health (FOPH) 2022,

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