Syphilis

Essentials

• Suspected syphilis should be verified with serological tests and the patient should be treated with the most efficient antimicrobial drugs.
• Syphilis is a notifiable infectious disease. Its treatment and contact tracing should be centralized to specialist STD centres or to other experts.

Aetiology and transmission

• The pathogen is the spirochete Treponema pallidum.
• Easily transmitted sexually and also from the mother to the foetus
• Untreated syphilis is contagious for about 2 years.
• Untreated syphilis in a pregnant woman may infect the foetus in all stages of the disease.

Clinical picture

• Asymptomatic incubation period lasts for 3-4 weeks after which two thirds of the patients have visible symptoms.

1. Primary symptoms (local infection)
   • An indurated non-tender ulcer (picture 1) in the genital region, sometimes also in the anus or the oral region
   • Local non-tender lymph node enlargement
2. Secondary stage 6-8 weeks after exposure (general infection)
   • General symptoms include malaise, fever and enlarged lymph nodes.
   • Roseola eczema (picture 2) resembles widely spread viral eczema or drug eruption.
   • Syphilides, i.e. formations of papules are found in the hands (picture 3) and feet (picture 4) or spread all over the body. May be large, cauliflower-like formations (condylomata latum) around the anus or necrotic in patients with a poor immune response (e.g. HIV).
   • Alopecia syphilitica, typical "moth-eaten" spotty baldness in some patients
3. Late symptoms occur in about one third of untreated patients in 10-30 years. The most important are neurological (atypical psychosis, paralytic dementia) and vascular symptoms (aortic aneurysm, valvular regurgitation).

Differential diagnosis

• Primary syphilis
  • Genital herpes Genital Herpes. Incubation time is short in primary infection, lesions occur in groups and they are painful. Lymph node enlargement is less pronounced, and the nodes are tender.
  • Infected coital or other traumas
  • Ulcus molle (soft chancre) Rare Sexually Transmitted Diseases: Chancres
• Secondary syphilis
  • Roseola may resemble pityriasis rosea Pityriasis Rosea, drug eruption Hypersensitivity to Drugs, measles (rubeola), German measles (rubella) or scarlet fever (scarlatina) Measles, Mumps and Rubella (Mmr).
  • Syphilides (picture 5) may resemble papular lichen ruber planus, psoriasis, scabies or infectious eczema of the feet (e.g. tinea). Condyloma latum may resemble condyloma acuminata Human Papillomavirus (Hpv) Infection.

Diagnosis

• Clinical picture
• Serology
  • Determination of Treponema pallidum antibodies is the primary screening test. The enzyme immunoassay test is specific and sensitive.
    • The test becomes positive within 3-4 weeks after infection.
    • The test identifies Treponema antibodies also in previously treated or latent cases in which the cardiolipin test remains negative.
    • Remember always to ask whether the patient has been treated for syphilis earlier.
    • A positive result is verified by immunoblotting.
    • The cardiolipin test becomes positive 3-4 weeks after infection. A low titre may suggest a serological scar of an earlier treated infection or latent syphilis.
  • TPHA test is used to confirm the cardiolipin test.
    • Becomes positive slightly later than that of the cardiolipin test.
    • Specific (almost 100%)
  • FTA-abs (fluorescence test) is a specific syphilis test used in special cases (neurosyphilis, suspicion of neonatal syphilis) as it detects also IgM antibodies.
• Nucleic acid detection methods are not in routine use.

Treatment Antibiotics for Syphilis during Pregnancy, Penicillin and Ceftriaxone for Early Syphilis

• Benzathine penicillin 2.4 million IU i.m. as a single dose (primary and secondary syfilis) or once a week for 3 weeks (latent syphilis).
• Neurosyphilis is treated with i.v. penicillin.
• For patients allergic to penicillin, ceftriaxone injections (1 g/day for 10-21 days) are an alternative.

Follow-up and identification of partners

• After antimicrobial therapy the cardiolipin test is performed at 1, 3 and 6 months, and if necessary at 12 months. In primary stage infection, the cardiolipin becomes negative in most cases, in other recent infections the titre falls by at least two dilutions when the treatment has been successful.
• All sexual partners who have been exposed to infection should be screened with the Treponema pallidum antibody test. If the result is negative, the test should be repeated after 2-3 months.
• The infection is reported to the health authorities according to the local regulations.