1. Treponema pallidum
Buga Rudolf
HTC LECTURE SERIES
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2. Introduction
•Causes syphilis
•Family – Spirochaetaceae
•Genus – Treponema
•Species -: T.pallidum sub. spp pallidum
T. pallidum sub. spp pertenue
T.caratenum
•Distribution – worldwide with 12m new cases yearly
(WHO)
•Remains problematic in developing countries due to
sequelae and the risks of congenital infections
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3. Transmission
• T.pallidum enters the body through minute abrasions on
the skin or mucous membrane
• Horizontal spread is through sexual contact
• Vertical spread is via transplacental infection of the
foetus
• Requires close personal contact
• Fragile outside the body
• Very sensitive to drying, heat & disinfectants
• Local multiplication leads to plasma cell, polymorph
and macrophage infiltration with later endarteritis
• Slow multiplication
• Incubation period is three weeks
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4. T. pallidum infection
•Infection is in three stages, i.e. primary, secondary
and tertiary
•Not all patients go through all the 3 stages
•A substantial proportion of patients remain
permanently free of the diseases after suffering 10
or 20 stages of infection
•20 stage may be followed by latent period of 3 – 30
years after which the disease may occur in the
tertiary stage
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5. T.Pallidum infection…
•Can survive in the body for many years despite a
vigorous immune response
•A healthy treponeme evades recognition and
elimination by the host by covering its surface richly
with lipid
•Tissue damage is mostly due to the host response
•Cannot be cultivated on artificial media
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6. Pathogenesis of syphilis
Transmission is through sexual contact
•Initial contact: Incubation period: 2-10 weeks,
depending on the infective dose
•Primary chancre at the site of infection
•Multiplication of treponemes at the site of infection,
associated with host response
•Further dissemination and invasion lead to host
response ( cell-mediated hypersensitivity)
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7. Pathogenesis of syphilis…
10 Syphilis.
• May occur within 1-3 months
• Enlarged inguinal nodes and spontaneous healing
• Treponemes proliferate in regional lymph nodes
20 Syphilis
• Incubation period: 2-6 wks
• Characterized by flu-like illness, myalgia, headache,
fever, mucocutaneous rash with spontaneous resolution.
Latent syphilis
• Incubation period: 3-30 years
• Treponemes dormant in liver and spleen
7

8. Pathogenesis…
Re-awakening and multiplication of
treponemes.
30 Syphilis
•Characterized by:
•Neurosyphilis, general paralysis of the
insane, tabes dorsalis
•Cardiovascular syphilis, aortic lesions,
heart failure
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9. Pathogenesis…
•Further dissemination and invasion leads
to host response (cell-mediated
hypersensitivity).
• Gummas in skin, bone, testis
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10. Pathogenesis…
Congenital syphilis
• Acquired after the first 3 months of
pregnancy
• Disease manifestations
•Serious infection results in intrauterine
death.
•Congenital abnormalities (may be
obvious at birth).
•Silent infection, which may not appear10

11. Laboratory diagnosis
• T. pallidum not be grown in-vitro
• Laboratory diagnosis depends on
• microscopy
• serology
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12. Laboratory diagnosis…
1. Microscopy:
• Specimens
•Exudates from primary chancre
•Dark ground microscopy (immediate)
•Ultra violet (UV) microscopy after staining
with fluorescein labeled anti-treponema
antibodies
•Organisms have tightly wound, slender coils with
pointed ends
•Sluggishly motile in unstained preparations
•Very thin, about 0.2mm in diameter
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13. Laboratory diagnosis…
• Cannot be Gram-stained
•Silver impregnation can be used to demonstrate the
organisms in biopsy material
2. Serology
•Serological tests divided into non-specific and
specific tests.
•Non-specific tests non-treponemal tests
• VDRL
• RPR.
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14. Laboratory diagnosis…
o Antigens are not treponemal in origin but extracted
from normal mammalian tissues (cardiolipin)
o Positive after 4-6 weeks of infection or 1-2 weeks of
primary infection
o Good screening tests
oFalse +ves:
oViral infection
o Collagen vascular diseases
oAcute febrile disease
o Post-immunization
oLeprosy
oMalaria
oPregnacy.
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15. Laboratory diagnosis…
•Specific tests:
• FTA-ABS
• TPHA
• TPHA uses Antigens extracted from T. pallidum
•FTA-ABS uses absorbed patient’s serum to remove
cross-reacting Abs.
•TPHA is a confirmatory test for the screening tests
•Remains positive for years and even after treatment
•Good for late syphilis
• But not a good indicator therapeutic response
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16. Laboratory diagnosis…
•False positives due to:
•Diseases associated with increased or
abnormal globulins
•Lupus erythematosus
•Skin diseases
•Antinuclear Abs
•Drug misuse
•Pregnancy
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17. Antibiotics/Control
•Antibiotics
• Penicillin is drug of choice for cases and carriers
• Tetracycline, doxycycline or erythromycin for patients
allergic to penicillin
•Control
• Prevention of 20 and 30 disease depends on early
diagnosis and adequate treatment
• Contact tracing with screening and treatment
• Screen for syphilis in those with several STDs
• Screen for syphilis in pregnant mothers to prevent
congenital syphilis
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