Syphilis is a bacterial infection that is usually caught by having sex with someone who is infected.
The bacteria that cause syphilis are called Treponema pallidum. They can enter your body if you have close contact with an infected sore, normally during vaginal, anal or oral sex, or by sharing sex toys with someone who is infected.
It may also be possible to catch syphilis if you are an injecting drug user and you share a needle with somebody who is infected.
Pregnant women can pass the condition on to their unborn baby. If untreated, syphilis can cause serious health problems for the mother and her baby, or cause miscarriage or stillbirth. This is why all pregnant women are offered a blood test to check if they have syphilis as part of routine antenatal screening.
It is extremely rare for syphilis to be spread through blood transfusions , as all blood transfusions in the UK are tested for syphilis.
Syphilis also cannot be spread by using the same toilet, clothing, cutlery or bathroom as an infected person, as the bacteria cannot survive for long outside the human body.
Three stages of disease
The symptoms of syphilis develop in three stages, described below.
stage 1 (primary syphilis) - symptoms of syphilis begin with a painless but highly infectious sore on the genitals, or sometimes around the mouth. If somebody else comes into close contact with the sore, typically during sexual contact, they can also become infected. The sore lasts two to six weeks before disappearing.
stage 2 (secondary syphilis) - secondary symptoms, such as a skin rash and sore throat, then develop. These symptoms may disappear within a few weeks, after which you experience a latent (hidden) phase with no symptoms, which can last for years. After this, syphilis can progress to its third, most dangerous stage.
stage 3 (tertiary syphilis) - around a third of people who are not treated for syphilis will develop tertiary syphilis. At this stage, it can cause serious damage to the body.
The primary and secondary stages are when you are most infectious to other people. In the latent phase (and usually around two years after becoming infected), syphilis cannot be passed on to others.
Tertiary syphilis is rare in the UK.
Read more detailed information about the symptoms of syphilis .
What to do
If you suspect you have syphilis, visit a genitourinary medicine (GUM) clinic, sexual health clinic or your GP as soon as possible.
The earlier syphilis is treated, the less chance there is of serious complications. Find your nearest sexual health clinic by searching by town or postcode.
Read more information about how syphilis is diagnosed .
How common is it?
The number of diagnoses of syphilis has risen substantially in the UK in the past decade. There have been several local outbreaks across England, the largest of which was in London between 2001 and 2004. Rates are highest among men who have sex with men.
However, syphilis is still one of the less common sexually transmitted infections in the UK. Between 2011 and 2012, there were 2,978 cases of syphilis diagnosed in the UK.
It is estimated that people with syphilis are three to five times more likely to catch HIV . This is because the genital sores caused by syphilis can bleed easily, making it easier for the HIV virus to enter the blood during sexual activity.
Infection with both HIV and syphilis can be serious because syphilis can progress much more rapidly than normal.
The only guaranteed way to prevent a syphilis infection is to avoid sexual contact or to only have sexual contact with a faithful partner who has been tested and does not have the infection.
You can reduce your risk of catching syphilis and other sexually transmitted infections (STIs) by:
Read more information about preventing syphilis .