What is syphilis?

Syphilis is a sexually-transmitted infection that is caused by bacteria called Treponema pallidum. It is transmitted during unprotected sexual activity with an infected person.

Signs and symptoms

The symptoms of syphilis vary according to the stage of infection:

Primary syphilis

The primary stage of infection is generally marked by the appearance of a painless ulcer, usually on the genitals. Sometimes there can be multiple ulcers, which can also appear on other areas of the body. However, one in four people do not develop this ulcer and the infection can continue unknown.

Secondary syphilis

If primary syphilis is left untreated, it can progress to secondary syphilis several weeks after the initial infection. It presents as a widespread rash on the trunk of the body, face, or extremities. In oral syphilis, red ulcers can also appear on the tongue. These symptoms can come and go for up to two years.

Other symptoms include:

  • Fever;
  • Fatigue;
  • Head and muscle aches;
  • Hair loss, and;
  • Sore throat and swollen lymph nodes.

It can also lead to liver, kidney, joint and eye problems.

Latent syphilis

Secondary syphilis can enter a latent stage if it continues to be untreated. Latent syphilis does not have any physical symptoms. However, individuals can remain infectious during the latency stage. Two-thirds of untreated people develop latent syphilis.

Tertiary syphilis

Up to one in three people with latent syphilis develop tertiary syphilis. It is caused by the body's immune response, triggered by the infection, damaging tissues such as the nervous system and blood vessels. This causes neurological and cardiovascular complications. It can also cause soft lumps in the skin called gummas, and/or red, scaly plaques that resemble psoriasis. Symptoms typically develop 3-20 years after the initial infection.

Typical symptoms include:

  • Loss of muscle coordination;
  • Numbness and paralysis;
  • Gradual onset of blindness, and;
  • Dementia.

Syphilis rash.A widespread rash on the back due to secondary syphilis. 


A collection of symptoms caused by permanent disorders of the brain. People with dementia lose their ability to think and reason clearly, which has an impact on their daily functioning.


An open sore in the skin or mucous membranes such as those of the stomach lining, intestine or mouth.


Syphilis is caused by bacteria called Treponema palladium. It can be spread through skin-to-skin contact or bodily fluids during unprotected vaginal, anal or oral sex with an infected person. The risk is increased if the infected person has a genital ulcer.

Risk factors

The risk factors for syphilis are:

  • Unprotected sex;
  • Multiple sexual partners, and;
  • Male-to-male sex.

Methods for diagnosis

Syphilis is diagnosed from blood and mouth swab samples. Regular sexual health check-ups are important if you are sexually active, particularly if involved in high-risk sexual behavior, such as men who have sex with men.

Types of treatment

Syphilis is treated with antibiotics, most commonly penicillin. If you are allergic to penicillin, and not pregnant, other treatment options include doxycycline and tetracycline. A single injection is enough to clear the infection which is in a primary, secondary or early latent stage. If the infection is in the late stages of latency or the stage of infection is unknown, three injections are administered over a three-week period, one injection per week.

The earlier you are treated, the less likely you are to have complications associated with the infection. All sexual contact should be avoided until the treatment course is finished. This is to reduce the risk of transmitting the infection on to others.

Potential complications


Syphilis of the brain (neurosyphilis) can occur at any stage of infection. This can cause mood swings and psychosis, as well as loss of memory and loss of sensation in the legs and feet.


Syphilis can be passed on to a unborn baby during pregnancy or at birth, by a mother with an untreated infection. Testing for syphilis prior to getting pregnant can allow for treatment, which then prevents the unborn baby from developing long-term complications and possibly death. Nearly half of all unborn babies infected with syphilis die shortly before or after birth. If the baby survives, they may be blind, deaf, have deformities of the face and/or nervous system problems.

HIV co-infection

Syphilis has been linked to an increased risk of contracting a HIV infection. One theory for this is that the sexual behaviors that lead to individuals acquiring syphilis, such as male-to-male sex and unprotected sex, increase the risk of acquiring HIV. Another theory is that genital ulcers caused by syphilis provide an entry point for HIV infection.

The signs and symptoms of syphilis in individuals with HIV infection can also be different. These individuals are likely to have more severe and unusual symptoms, such as multiple ulcers that are deeper and ulcers on the skin and mouth. There is an increased risk of neurosyphilis. HIV infection can also speed up the course of the syphilis infection. Similarly, some evidence suggests that syphilis can further lower immunity in individuals with HIV infection.


A virus transmitted mainly by sexual or blood-to-blood contact, that infects cells of the immune system. It is the causative agent of acquired immune deficiency syndrome (AIDS).


An abnormal mental state characterized by a loss of contact with reality.


An open sore in the skin or mucous membranes such as those of the stomach lining, intestine or mouth.


Treatment with antibiotics clears up the infection in a few weeks. An infection with syphilis does not prevent contracting future infections.


It is important to practice sex safe using appropriate protection, limiting the number of sexual partners to those who are free of sexually-transmitted infections, and regularly testing for such infections. You can reduce your risk of becoming infected with syphilis by wearing a condom during oral, vaginal and anal sex. If you have syphilis you should inform your sexual partner for timely treatment and minimizing of reinfections.

Using condoms can reduce the risk of contracting syphilis during sex. 


  1. Clinics - Oral manifestations of syphilis. Accessed 10 July 2014 from link here
  2. Effectiveness of condoms in preventing sexually transmitted infections. Accessed 10 July 2014 from link here
  3. STD Facts - Syphilis (Detailed). Accessed 10 July 2014 from link here
  4. Syphilis: A Reemerging Infection - American Family Physician. Accessed 10 July 2014 from link here

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