Syphilis

Comments from Expert Advisory Group

1. Syphilis is caused by the spirochete Treponema pallidum (T. pallidum).
2. Acquired syphilis is commonly transmitted through sexual contact, but can also be transmitted by direct vascular inoculation (people who inject drugs or rarely through transfusions) or direct cutaneous contact with infectious lesions. Vertical transmission can occur in utero or in the peripartum period leading to congenital syphilis.
3. Acquired syphilis can be divided into two phases: early and late.
4. Early syphilis is more infectious than late syphilis and is further divided into primary syphilis (chancre); secondary syphilis (systemic phase commonly presenting with a rash) and early latent (asymptomatic within 2 years of acquisition).
5. Late syphilis can present as late latent infection (asymptomatic greater than 2 years since acquisition); gummatous syphilis; cardiovascular syphilis or neurosyphilis. Symptomatic late syphilis can present 20 to 30 years after acquisition.
6. In Ireland since the 2000’s the majority of early infectious cases of syphilis have been in gay, bisexual and other men who have sex with men (gbMSM). There have been concerns more recently regarding an increase in cases of syphilis among the heterosexual population. Syphilis testing is indicated in all sexually active gbMSM presenting with an anogenital ulcer or generalised rash and should be offered to all gbMSM requesting STI testing or considered to be at risk of STIs.
7. Congenital syphilis is uncommon in Ireland and preventable with antenatal screening and appropriate maternal and neonatal management. It is important to note that other countries have observed increases in congenital syphilis cases, highlighting the importance of offering syphilis testing to all people booking for antenatal care. People with positive syphilis serology in pregnancy should be referred promptly to a dedicated GUM clinic for assessment and management to reduce the risk of congenital infection.
8. The screening test for syphilis is T. pallidum EIA (enzyme immunoassay) which checks for antibodies to T. pallidum. In individuals with syphilis, this test remains positive regardless of treatment or risk of reinfection. All patients with positive syphilis serology should be discussed with a specialist in Genitourinary Medicine or Infectious Diseases.
9. Parenteral penicillin is first line treatment. The type and duration of treatment is determined by the clinical presentation and stage of syphilis at presentation. Patients with newly diagnosed syphilis should be referred to a GUM clinic for further management and treatment.
10. Individuals diagnosed with syphilis should be offered testing for other STIs including HIV, hepatitis B, chlamydia and gonorrhoea.
11. Hepatitis C (HCV) testing should be considered part of routine sexual health screening in the following circumstances: gbMSM; People living with HIV; Commercial sex workers; People who inject drugs (PWID); Partners of the above should also be considered for HCV testing.
12. Partner notification is an important part of the management of early syphilis and is best done within a specialist sexual health clinic. Patients with newly diagnosed syphilis should be referred to a GUM clinic for management and treatment.
13. Syphilis is a notifiable disease. Notification process is usually initiated by the testing laboratory.

Treatment options

• Parenteral penicillin – the dose, duration and route (IV versus IM) is determined by the stage of infection and clinical circumstances.
• Oral doxycycline – the dose and duration is determined by the clinical circumstances.
• Decisions around treatment should be made by a clinician with expertise and experience in managing syphilis.

Patient information

• Syphilis patient information leaflet
• Patient information on STIs and genital conditions is available at the HSE Sexual Health and Crisis Pregnancy website.
• Information for gbMSM on sexual health is available at the Man2Man website.
• Information on the free HSE home STI testing service.

Safe Prescribing

Visit the safe prescribing page

• Visit the Health Products Regulatory Authority (HPRA) website for detailed drug information (summary of product characteristics and patient information leaflets). Dosing details, contraindications and drug interactions can also be found in the Irish Medicines Formulary (IMF) or other reference sources such as British National Formulary (BNF) / BNF for children (BNFC).

Reviewed April 2024