Syphilis is a sexually transmitted infection caused by a spiral-shaped bacterium called Treponema pallidum. It spreads mainly through sexual contact but may also spread from mother to fetus during pregnancy. Syphilis is common in developing countries, and in recent years it has reappeared in many developed countries due to unsafe sexual practices.
Mode of Transmission
a) Sexual Transmission
- Entry through broken skin or mucous membranes of genitals, mouth or rectum
- Spread through vaginal, anal and oral sex
- Can spread through intimate kissing if oral lesions are present
b) Non-Sexual Transmission
- Rare accidental inoculation
- Blood transfusion from an infected person
- Mother-to-child transmission during pregnancy
Stages of Syphilis (Simplified)
Syphilis progresses in three main stages, depending on how long the infection has been present.
1. Primary Syphilis
Appears after an incubation period of 10–90 days (average 21 days).
- Main symptom: a single, painless ulcer called a chancre
- Firm, round and clean-looking ulcer
- Commonly on genitals, anus, mouth or lips
- Regional lymph node enlargement
- Chancre heals on its own in 3–6 weeks — but the infection continues if untreated
2. Secondary Syphilis
Develops about 2–3 months after primary syphilis if not treated.
- Generalized lymph node enlargement
- Widespread rashes: pale red or pink, non-itchy, symmetric
- Rashes appear on trunk, hands and feet
- Soft, painless mucous patches in mouth, pharynx, vagina or penis
- Flu-like symptoms may occur
- Highly infectious stage
3. Tertiary Syphilis
Occurs 2–3 years or more after secondary syphilis if untreated.
- Not highly infectious
- Bacteria difficult to detect in lesions
- Cardiovascular syphilis: aortic aneurysm
- Neurosyphilis: affects brain and spinal cord
- Gummas: rubbery, destructive lesions that may affect liver, bones, skin or testis
Clinical Features
Primary Stage
- Painless chancre at entry site
- Swollen lymph nodes
Secondary Stage
- Non-itchy rashes on various parts of the body
- Mucous patches: silver-grey, painless erosions
- Fever
- Sore throat
- Headache
- Weight loss
- Muscle aches
Tertiary Stage
- Dementia
- Blindness
- Paralysis
- Numbness
- Aortic aneurysm
Diagnosis
The bacteria cannot be cultured, so diagnosis is based on microscopic examination and blood tests.
1. Dark-Field Microscopy
- Used for moist lesions such as chancres
- Shows characteristic motile spirochetes
2. Serological Tests
- VDRL test (Venereal Disease Research Laboratory): detects antibodies against cardiolipin
- RPR (Rapid Plasma Reagin): similar to VDRL
- TP-PA (Treponema pallidum particle agglutination) test
- DFA-TP (Direct fluorescent antibody test)
VDRL is also used for diagnosing neurosyphilis through cerebrospinal fluid.
Management of Syphilis
First-Line Treatment: Penicillins
- Benzathine penicillin G 2.4 million units IM — long-acting, treats early syphilis
- Maintains adequate serum levels for 3–4 weeks
- Procaine penicillin: 600,000 units IM daily for 10–14 days
- 1% lidocaine may be added to reduce injection pain
Alternative Options
- Ceftriaxone (IM or IV)
- Doxycycline: good CSF penetration
- Tetracycline
- Azithromycin: effective for early stages
- Erythromycin: least effective; poor CSF penetration
Note: Penicillin allergy is an absolute contraindication for ceftriaxone due to possible cross-reaction.
Treatment for Late/Tertiary Syphilis
- Benzathine penicillin 2.4 million units IM once weekly for 3 weeks
- Procaine penicillin daily for 17–21 days
- If allergic or refusing injections: doxycycline or tetracycline for 28 days
Prevention
- Use condoms during sexual contact
- Sex education for teenagers and high-risk groups
- Awareness about sexually transmitted infections
- People with syphilis must avoid sexual activity until lesions heal
- Sex partners should be tested and treated if needed
- Follow-up blood tests to confirm cure
- Pregnant women should be screened early for syphilis
- Test for other STIs such as HIV, gonorrhoea, chlamydia
Detailed Notes:
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