What is syphilis?

What is Syphilis?

Syphilis is a systemic disease caused by the spirochete bacterium Treponema pallidum that can progress through multiple stages with varied clinical manifestations if left untreated, affecting multiple organ systems and potentially leading to significant morbidity and mortality. 1

Disease Overview

Syphilis is primarily transmitted through:

• Sexual contact with an infected partner
• Congenital transmission from an infected pregnant woman to her fetus 2

The disease progresses through several well-defined stages:

Primary Syphilis

• Characterized by one or more painless chancres (ulcers) at the site of infection
• Chancres typically appear 3-4 weeks after exposure
• Highly infectious stage
• Regional lymphadenopathy may be present 1

Secondary Syphilis

• Occurs 4-10 weeks after primary infection
• Manifestations include:
  • Disseminated skin rashes (often on palms and soles)
  • Mucocutaneous lesions
  • Generalized lymphadenopathy
  • Condyloma lata (in genital or perineal regions)
  • Fever and other systemic symptoms
• Highly infectious stage 1

Latent Syphilis

• No clinical manifestations present
• Infection detectable only through serologic testing
• Divided into:
  • Early latent (acquired within preceding year)
  • Late latent or unknown duration (all other cases)
• Decreased infectiousness 1

Tertiary (Late) Syphilis

• Can develop years to decades after initial infection
• Manifestations include:
  • Gummatous disease (granulomatous lesions)
  • Cardiovascular syphilis (aortitis, aortic aneurysm, aortic regurgitation)
  • Neurologic involvement
• Associated with significant morbidity and mortality 1, 3

Neurosyphilis

• Can occur at any stage of infection
• Presentations include meningitis, stroke, cranial nerve dysfunction, and tabes dorsalis
• Requires specific diagnostic and treatment approaches 1

Diagnosis

Diagnosis of syphilis involves:

1. Direct detection methods (for early syphilis):

   • Darkfield microscopy of lesion exudate
   • Direct fluorescent antibody tests 1

2. Serologic testing (most common approach):

   • Nontreponemal tests (VDRL, RPR) - correlate with disease activity
   • Treponemal tests (FTA-ABS, MHA-TP, TP-PA) - typically remain positive for life
   • Both test types are required for diagnosis as false positives can occur with nontreponemal tests alone 1

3. CSF examination - required for suspected neurosyphilis 1

Treatment

The cornerstone of syphilis treatment is:

Primary, Secondary, and Early Latent Syphilis

• Benzathine penicillin G 2.4 million units IM in a single dose 1, 2

Late Latent Syphilis or Latent Syphilis of Unknown Duration

• Benzathine penicillin G 7.2 million units total, administered as three doses of 2.4 million units IM at one-week intervals 1

Neurosyphilis

• Requires specific regimens with higher doses of penicillin 1

Alternative Regimens (for non-pregnant patients without neurosyphilis)

• Doxycycline 100 mg orally twice daily for 14 days (primary, secondary) or 28 days (late)
• Tetracycline 500 mg orally four times daily for 14 days (primary, secondary) or 28 days (late)
• Note: Macrolide resistance has limited the use of azithromycin 2, 4

Special Considerations

Pregnancy

• Penicillin is the only proven effective treatment
• Pregnant women with penicillin allergy should undergo desensitization 1, 5

HIV Co-infection

• Treatment regimens are the same as for HIV-negative individuals
• More careful follow-up may be required 1

Congenital Syphilis

• Can cause severe complications including stillbirth, prematurity, and multisystem disease
• Requires specific diagnostic criteria and treatment approaches 1, 6

Follow-up

• Quantitative nontreponemal test titers should be obtained to monitor treatment response
• A fourfold decline in titer (equivalent to two dilutions) is expected within 6 months for primary/secondary syphilis and 12-24 months for latent/late syphilis 1, 4

Prevention

• Regular screening of high-risk populations
• Treatment of infected individuals and their contacts
• Safe sex practices including condom use
• Early prenatal care with universal screening during pregnancy 2, 5