What is syphilis?

Syphilis is an infectious disease caused by a bacterium (germ) called Treponema pallidum. Syphilis is one of the less common sexually transmitted infections (STIs) in the UK. The number of cases are, however, rising. In the UK, the rates of infection are highest amongst homosexual (gay) men – or men who have sex with men.

Syphilis is much more common in other countries, especially in developing parts of the world.

How do you get syphilis?

Syphilis is a sexually transmitted infection. The infection is passed from person to person through contact with a syphilis ulcer (described below). So, depending where the ulcer is, the infection can be passed on during vaginal, anal, or oral sex.

Syphilis is not spread by toilet seats, door knobs, bath tubs, shared clothing, etc. You need to have close direct contact with an infected person.

If you are pregnant, you can pass on syphilis to your fetus (unborn baby) via the placenta. Infection in the fetus can lead to serious problems in pregnancy (see later) and/or congenital syphilis.

Syphilis is also transmitted in the blood. Syphilis can be transmitted through receiving infected blood products (a blood transfusion). In the UK, all blood products are rigorously screened for infections, including syphilis and HIV. However, syphilis can be passed from person to person through sharing needles between injecting intravenous drug users (IVDUs).

Classification of syphilis

Syphilis infection is divided up into:

  • Acquired syphilis. This is generally transmitted through sex with an infected partner. There are several stages:
    • Primary syphilis. This is the earliest stage, and generally occurs from 10 days to 3 months after infection. It typically causes a painless ulcer on the genitals.
    • Secondary syphilis. This is the second stage of syphilis. Many different symptoms can occur (see later) but usually last several weeks. They can, however, come and go for up to two years.
    • Latent (hidden) syphilis. This occurs after the symptoms of secondary syphilis have cleared. With latent syphilis you have no symptoms. Latent syphilis can last for many many years. It is divided into two types:
      • Early latent syphilis. This lasts for a year or so and you are still infectious – that is, you can pass syphilis on to other people.
      • Late latent syphilis. About two years after secondary syphilis has cleared you can become non-infectious and are no longer able to pass syphilis on to others.
    • Tertiary syphilis. This is the final stage of syphilis. It can affect many organs of the body, including the brain and heart. It can result in death.
  • Congenital syphilis. This means syphilis infection that is passed from a pregnant mother to her unborn baby. It is divided into:
    • Early congenital syphilis. This is diagnosed in the first two years of life.
    • Late congenital syphilis. This is diagnosed after the age of two years.

What are the symptoms of syphilis?

If left untreated, the infection typically follows the pattern of four stages as described above – primary, secondary, latent, and tertiary syphilis. Neurosyphilis is considered separately, as it can occur at any stage of syphilis.

Primary syphilis

Typically, one small ulcer (sore) develops where syphilis bacteria enter the body. This ulcer is called a chancre. It is commonly on the penis in men, on the vulva or vagina in women, or on the anus (either men or women). The ulcer usually appears about 2-3 weeks after having sex with an infected person, but it may appear anytime up to three months later.

The ulcer is usually painless and about the size of a small coin. A clear fluid (serum) oozes from the ulcer. This fluid is highly infectious, and teeming with bacteria. The ulcer lasts up to six weeks, then heals – but this does not mean the infection has gone.

When you have a syphilis ulcer, the nearby lymph nodes (glands) in your groin may swell. These feel like small lumps at the top of your legs in the groin crease.

Sometimes the primary stage is non-typical. For example:

  • You may have more than one ulcer.
  • The ulcer may be painful.
  • Pus may come from an ulcer.
  • The ulcer may be in your mouth (if you catch the infection during oral sex), or in the rectum (from anal sex).
  • The ulcer may be on the cervix in women, and is not seen or felt.
  • You may have no symptoms, or very mild symptoms that you take little notice of.

People with human immunodeficiency virus (HIV) infection as well as syphilis tend to get multiple, deep, large chancres.

Secondary syphilis

If the primary ulcer is not treated, or not noticed, the bacteria may spread to many parts of your body. Symptoms of secondary syphilis may then develop. These tend to appear a few weeks after the ulcer has healed, but may develop whilst the ulcer is healing. Symptoms of secondary syphilis are numerous, and vary from person to person. Some symptoms are nonspecific which are similar to those that can occur with other medical problems.

Symptoms of secondary syphilis include:

  • Rash. This is a common symptom of secondary syphilis. The rash consists of dark patches that appear on the skin, each about the size of a penny. The rash may occur in many areas of the body, or be only in a few areas. However, the palms of the hands, and the soles of the feet are almost always involved. The rash is not usually itchy or painful.
  • Condylomata lata are wart-like growths that may develop around the penis in men, or vagina in women.
  • General malaise (feeling of unwellness) and lethargy (tiredness).
  • Mild fever and headaches are common.
  • Sore throat.
  • Joint pains.
  • Swollen lymph nodes may develop in various places in your body (such as your groin, armpits or neck).
  • Patchy hair loss (alopecia) can occur but is not that common.
  • Less commonly, inflammation may develop in other parts of your body such as the liver, eyes, brain, or kidneys.

Without treatment, the rash and other symptoms from secondary syphilis usually go after several weeks. However, they may come and go for up to two years.

Latent (hidden) syphilis

After the symptoms of secondary syphilis have cleared, you may not have any symptoms for several years. In this latent period you may think that the disease has gone. In some cases, there is no further development. In the first year or so of latent syphilis you can still pass the infection on. After this time, you are no longer infectious to others, but you still have syphilis infection. If left untreated, the bacteria can slowly damage various parts of your body, and symptoms of the tertiary (third) stage may eventually appear.

Tertiary syphilis

Tertiary syphilis can develop many years after the initial syphilis infection. Some manifestations of the disease can occur up to 50 years later. Many of these complications are potentially very serious and can make you extremely unwell. Some problems are life-threatening and can lead to death if untreated.

Syphilis is not considered to be infectious in its tertiary stage. Tertiary complications are slowly progressive and can affect any organ of the body.

Tertiary syphilis may cause several types of complications:

  • Neurological complications. This is also called neurosyphilis (see next section).
  • Cardiovascular complications. These are problems affecting the heart and blood vessels (the cardiovascular system). Most commonly, syphilis affects the main blood vessel leading out of the heart (the aorta). Inflammation here can cause weakening of the aorta, which can stretch, forming an aneurysm. Aneurysms have thin weak walls and can rupture (burst), potentially leading to death. Even if an aneurysm does not rupture, it can seriously affect one of the heart valves (the aortic valve), leading to a heart murmur. In turn, the heart does not pump very well, and becomes distended with blood, a condition known as heart failure. (See separate leaflets called ‘Heart Failure’ and ‘Heart and Blood Vessels’ for more information.)
  • Gummatous disease. Gummas are soft growths (tumours) caused by inflammation. They are not cancerous tumours but are chronic (long-term) and can affect any part of the body. They can grow on the skeleton and affect the joints; they can also cause large lumps in or under the skin. Gummas can grow on the internal organs (such as the liver) and affect organ function or even cause organ destruction. Quite commonly they appear on the leg, below the knee. Gummas may be single or multiple, and can vary in size between one and several centimetres. They can cause bone pain at night, and the chronic inflammation can cause a fever and anaemia (a low blood count).


This means that the syphilis infection is affecting the central nervous system (CNS). The CNS includes the brain, the spinal cord and their coverings (the meninges).

Neurosyphilis can occur at any stage of syphilis infection, although, commonly it is thought of as a tertiary complication, occurring late on in untreated disease. Neurosyphilis is generally a slow and gradual loss of mental and physical function, with alterations in mood and personality. It is possible to have a more acute illness which is quicker in onset and more severe. On average it occurs between 1 and 10 years after the initial infection.

Neurosyphilis used to be a lot more common in the days before antibiotic treatment was widely available. Probably between 2 and 4 people in every 10 with syphilis infection, developed neurosyphilis. Neurosyphilis is now more common in people who also have HIV infection.

The four main types of neurosyphilis are:

  • Asymptomatic neurosyphilis (no symptoms). Before effective antibiotic treatment was available, 3-4 people in every 10 with secondary syphilis had asymptomatic neurosyphilis. Lumbar puncture (spinal tap) examination of the cerebrospinal fluid (CSF or spinal fluid) showed the presence of the T. pallidum bacterium.
  • Meningovascular syphilis. This involves inflammation of the coverings and small blood vessels in the brain. On average, this complication occurs about seven years after initial syphilis infection. It can cause headaches and dizziness, and can result in a stroke. Meningitis (inflammation of the meninges – the coverings of the brain), can also occur as a more acute complication. Blindness and deafness can result from meningitis or meningovascular syphilis infection.
  • General paresis. This is also known (historically) as ‘general paresis of the insane’. It is a chronic dementia that represents a severe complication of neurosyphilis, usually in its late stages. On average, death follows within only 2-3 years. There is progressive personality change, memory loss and confusion. Sometimes there is depression or hallucinations.
  • Tabes dorsalis. This is another, late form of neurosyphilis, more common before antibiotic treatment. The nerves in the spinal cord are damaged, leading to poor balance and co-ordination, and problems with walking. Additionally, there is loss of pain and temperature sensation in the feet and, as a result, deep foot ulcers can occur.

Syphilis in pregnancy and congenital syphilis

Syphilis infection can be passed from a pregnant mother to her fetus (unborn baby), via the placenta. This can result in serious pregnancy complications such as:

  • Miscarriage. This means death of the fetus before 24 weeks’ gestation.
  • Stillbirth. This means death of the fetus after 24 weeks’ gestation.
  • Hydrops. This is a condition of severe swelling due to fluid (oedema) in the fetus. It is a serious condition that can result in death of the fetus.
  • Polyhydramnios. This is a condition of pregnancy where there is an abnormally large amount of amniotic fluid surrounding the fetus. This can cause serious pregnancy complications such as preterm (premature) labour, placental abruption (where the placenta suddenly detaches from the uterus) and postpartum haemorrhage (PPH) when there is excessive bleeding at delivery.
  • Preterm (premature) labour. This is labour and delivery of the baby before 37 weeks’ gestation.

Congenital syphilis is syphilis infection in the baby, or child, transmitted from the mother. It is divided into early and late cases, dependent on when the child shows symptoms of syphilis infection (see classification of syphilis section, above).

Early symptoms and signs of untreated congenital syphilis occur before the age of two years. They include: rashes (typically a peeling rash of the palms, the soles and around the mouth and anus), enlarged liver and/or spleen, abnormal bone X-rays, anaemia, enlarged lymph nodes (glands) and jaundice.

Late congenital syphilis is rare. It can cause symptoms similar to neurosyphilis in an adult. Problems affecting the eyes and joints are seen, as well as deafness, gummas and dental abnormalities.

How is syphilis diagnosed?

Syphilis can be difficult to diagnose just based on symptoms. This is because there are very many different symptoms, and often these symptoms can occur with other conditions. This is why syphilis used to be called ‘the Great Imitator’ because it mimics many other illnesses.

Now, however, there are specific tests for syphilis. So, as long as it is suspected as a possibility, it can be easily diagnosed with a test.

Genito-urinary medicine (GUM) clinics often perform STI screening. Testing for syphilis is part of this. There are two main types of test:

  • A swab (small sample) from the sore can be looked at under the microscope. The typical bacteria can be seen.
  • If the ulcer has gone, a blood test can detect if you have syphilis. The blood test looks for proteins in your blood, called antibodies. These antibodies are made by your immune system in order to fight infection. The antibody test can be positive or negative. A negative result might mean the test has been carried out too early. It can take a while for the antibodies to be present in the blood. If this is the case, a repeat test will usually be advised after a period of about 3 months. A positive test will either mean that you have syphilis or have had syphilis in the past.

Additionally, all pregnant women are screened for syphilis. This is part of the routine antenatal blood tests that are usually done between 8 and 16 weeks’ pregnancy.

Are any other tests needed?

In primary and secondary syphilis, generally no other tests are required. However, in tertiary syphilis, where there are complications affecting other parts of the body, further tests may be required.

Other tests may include a chest X-ray or echocardiogram (ultrasound of the heart) in cardiovascular syphilitic disease. Brain scans (such as computed tomography (CT) or magnetic resonance imaging (MRI) may be needed if there is suspected neurological (brain) involvement.

What is the treatment for syphilis?

Because syphilis is caused by a bacterium, it is readily treatable with antibiotics.

  • Penicillin injections are the usual treatment. This kills the bacteria and prevents the disease from progressing any further. The injections are given intramuscularly (IM), usually into the buttock. A single dose can be given for primary and secondary syphilis. Later stages may need a course of three injections, at weekly intervals. Neurosyphilis usually requires more frequent, daily doses for a couple of weeks.
  • Other antibiotics are sometimes used if you are allergic to penicillin.

It is important to avoid sex until the syphilis sores are completely healed and a test confirms that the syphilis infection is gone. Remember that it is not just penetration and ejaculation that lead to transmission of syphilis. It is caught by close skin-to-skin (sexual) contact with the oozing serum from the chancre.

Treatment during the primary or secondary stages of the disease will usually prevent any permanent long-term damage.

Some of the problems associated with tertiary syphilis cannot be completely cured with antibiotics, but antibiotic treatment may prevent further worsening of your condition. Cardiovascular (heart and blood vessel) complications may still get worse, despite treatment.

If you have syphilis, you should usually be investigated, treated and followed up by a GUM clinic. If you have caught syphilis, there is a good chance that you may also have another STI too. A GUM clinic will perform swabs and blood tests to exclude other STIs such as chlamydia, gonorrhoea and HIV. (See separate leaflet called ‘Sexually Transmitted Infections’ for more information.)

The GUM clinic can organise contact tracing which means informing your previous sexual partners (confidentially and anonymously) that they need testing for STIs, including syphilis. This is especially important if you are unable or unwilling to do this yourself.

It is important to tell your current sexual partner(s) so that they can also be tested, and treated if necessary.

Can syphilis be prevented?

If you practise safe sex, and always use a condom, your risk of catching syphilis (and other STIs) is very much reduced. However, condoms do not provide complete protection, as syphilis ulcers can sometimes be on areas not covered by a condom.

If you have had syphilis, and had it treated, you can still be re-infected if you have sex with an infected person. (The antibodies in your blood are not sufficient to protect you from another infection if you come into contact with syphilis again.)

What should I do if I think I have syphilis?

If you suspect that you have syphilis, or another STI, then see your GP or contact your local GUM clinic.

You can go to the local GUM clinic without a referral from your GP, and many clinics offer a ‘walk-in’ service. All treatment at a GUM clinic is completely confidential and your GP does not have to be informed, if you do not wish them to be (although sometimes this can be very helpful as part of your continuing holistic medical care).
You can find out where your nearest GUM clinic is either by asking your GP practice, contacting your local hospital, checking in the telephone directory or looking on the internet.

Further support and information

British Association for Sexual Health and HIV (BASHH)

Web: www.bashh.org
A professional association, but their website includes contact details of GUM clinics as well as lots of information on STIs, including syphilis.


Web: www.fpa.org.uk
Helpline: 0845 122 8690
Provides information and advice on all aspects of contraception and sexual health.

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