Syphilis is a sexually transmitted infection. New diagnoses of syphilis have increased dramatically in the UK and many other countries over the past few years.

It is an unpleasant infection, and if it is left untreated, syphilis can cause damage to the heart and brain and this can lead to death.

Syphilis can be harder to cure in people with HIV, especially if you have a low CD4 cell count, and it is particularly important that it is treated early.

Syphilis is caused by bacteria. There are three stages to the disease; primary syphilis; secondary syphilis and tertiary syphilis. During the primary and secondary stages it is easy to pass the infection on to other people during sex.

Syphilis can be contracted from contact with syphilitic sores during unprotected anal, oral or vaginal sex. It can also be transmitted by close physical contact with syphilitic rashes and lesions, which can be anywhere on the body. You can also contract syphilis from infected blood.  

Untreated primary and secondary syphilis can make a person with HIV more infectious. Having syphilis may also make it much more likely that an HIV-negative person will be infected with HIV if exposed to the virus.

Using a condom for oral, anal, or vaginal sex offers protection from infection with syphilis, or from passing on the infection to somebody else.

Protection is not complete because sores and rashes aren't always in the area protected by condoms. People who are sexually active are advised to have regular sexual health check-ups. Routine sexual health check-ups include a blood test for syphilis. It's also a good idea to mention to the doctor or nurse any unusual rashes or sores.  

Most HIV clinics have an associated sexual health clinic where free and confidential treatment can be obtained without referral from your GP or your HIV doctor.

Syphilis can cause a range of symptoms or, sometimes, none at all. In the early stage of disease, symptoms may be easily missed. Syphilis can progress more quickly and severely in people with HIV, and may present slightly different symptoms.

Shortly after becoming infected with syphilis (primary syphilis) a small sore, spot or ulcer (called a chancre) may appear at the site of infection – usually the anus, mouth, penis or vagina. The chancre does not hurt and usually heals quite quickly. Some people have swollen glands at this time.

Secondary syphilis can cause a rash, swollen glands, fever, muscle pain, headache, ringing in the ears, and in rare cases, meningitis – inflammation of the lining of the brain. Dark brown sores, about the size of a penny piece may also appear on the hands and feet. The rash and sores are highly infectious. Secondary syphilis normally develops about six months after a person is first infected with syphilis

Tertiary syphilis usually develops within ten years of infection and can cause damage to almost all the internal organs and the brain (neurosyphilis). If left untreated syphilis can cause death.

A general sexual health check-up will include a blood test for syphilis, and any lesions will be swabbed. It can take up to three months for the body to develop antibodies to the bacteria that cause syphilis, so a test taken shortly after exposure may not detect infection. There is some evidence to suggest that tests for syphilis are not as reliable in people with HIV if they have a very low CD4 cell count.

Syphilis is usually treated with a course of penicillin injections. People who are allergic to penicillin are given a course of antibiotic tablets. People with HIV usually receive higher doses of medication for longer. To ensure that the syphilis is completely cured it is vital to have all your prescribed injections or take all your medication. To avoid infecting other people with syphilis, or being re-infected with the bacteria, it is important to avoid sex altogether until treatment has been completed and you have been given the all clear.

If you are allergic to penicillin treatment for syphilis is normally with the oral antibiotic doxycycline for two weeks.

A strain of syphilis has natural resistance to the antibiotic, azithromycin and this drug should not be used for the treatment of syphilis unless tests have shown that this antibiotic works against the infection.

Blood tests will be carried out at intervals of 1, 2, 3, 6, 12 and 24 months to ensure the infection has gone.