Medically Fit For Exams
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Syphilis - Dr Deac Pimp


  • A bacterial sexually transmitted infection caused by spirochete Treponema Pallidum


Risk factors

  • Unprotected sex
  • MSM
  • Sex abroad
  • Multiple partners


Differential diagnoses

  • Herpes
  • Chancroid
  • LGV
  • Warts (HPV)
  • Molluscum contagiosum
  • Donovanosis
  • Ingrown hair
  • Dermatitis



  • 10.6 million cases worldwide per year
  • 5,288 new cases in England in 2015, a 19.9% increase from the previous year
  • Rapid rise in new cases, especially in MSM



  • Infection with Treponema pallidum, a spirochete bacteria
  • Can be caught through:
    • Oral, anal or vaginal sex
    • Kissing
    • Direct physical contact
    • Vertical transmission in pregnancy or childbirth


Clinical features

  • Primary syphilis
    • Lump which develops into painless ulcer: chancre
      • Red base, clean base, discharging clear fluid
      • Most commonly around coronal sulcus, glans, inner prepuce, vulva
      • Also found on shaft, mouth, throat, perianal, fingers, buttocks, cervix
    • Lasts 4-6 weeks
    • Lymphadenopathy in groin
  • Secondary syphilis:
    • Usually 6 weeks after primary syphilis, but can be months
    • Approx 25% progress to secondary syphilis
    • Condyloma lata: round (flat) grey/pink papules in moist areas
    • Macular rash, non-itchy, on palms, soles, face
    • Mild systemic symptoms:
      • Nocturnal headache
      • Fever
      • Malaise
    • Less common:
      • Moth-eaten alopecia (round patches of hair loss)
      • Meningitis
      • Anterior uveitis
      • Cranial nerve palsies
  • Latent syphilis
    • Early latent = positive serology, but no symptoms or signs, first 2 years
    • Late latent = positive serology, infected over 2 years, but no clinical manifestations. No longer infectious
  • Tertiary syphilis
    • Is no longer infectious
    • This is also called ‘late syphilis’ and is said to occur 2 years after initial infection
    • Neurological
      • Evidence of treponema in CSF
      • May or may not be symptomatic
      • Usually occurs many years after infection
      • Tabes dorsalis: demyelination of dorsal columns, signs and symptoms are varied, but can include paraesthesia, ataxia, incontinence, deafness, visual impairment
      • Dementia
      • Meningeal abnormalities
    • Cardiovascular
      • Aortitis
      • Manifests as aortic regurgitation, aortic aneurysm or angina
    • Gummatous
      • Fibrous nodules occurring typically on face, but can be anywhere, especially bone and skin
      • Can grow very large and be disfiguring



  • Progressive infection with spirochete bacteria Treponema pallidum
  • When viewing on darkfield microscopy:
    • Is 10 micrometers long, 0.2 micrometres wide
    • Twisting/corkscrew like movement
    • 8-10 coils visible



  • Dark field microscopy
  • Serology:
    • Antigen based assays
    • Treponemal/specific markers TPPA (T. pallidum particle agglutination)/TPHA (T. pallidum haemagglutination assay)
    • Non-treponemal/non-specific cell markers VDRL (venereal disease reference lab)/RPR (rapid pasmin regain), can be used to stage disease – is a marker of disease activity. Should be performed if specific markers are positive
  • PCR



  • Staging to allow correct treatment
  • Early syphilis:
    • Benzathine penicillin IM into buttock 2.4mu 1 dose
    • If in 3rd trimester pregnancy, give 2 doses 1 week apart
  • Late syphilis:
    • Benzathine penicillin IM into buttock 2.4mu 3 doses over 3 weeks
  • Neurosyphilis
    • Benzathine penicillin IM 1.8-2.4 mega units once daily IM for 14 days
    • AND oral probenecid 500mg QDS
  • Can use doxycycline if anaphylactic to penicillin, but try to avoid as it is not as effective



  • If untreated 1/3 develop late syphilis complications
  • Serology remains positive for life
    • Antibodies
    • VDRL/RPR reduce with treatment and progression
  • If infected with early syphilis during pregnancy, there is a 70-100% chance of passing on to the child. They require testing at birth and every 3 months until negative
    • All pregnant women offered screening
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