Syphilis is caused by the spirochete Treponema pallidum. It is transmitted sexually or congenitally from mother to fetus. Syphilis increases the risk of HIV transmission. It has various stages including primary, secondary, latent, and tertiary syphilis. Laboratory diagnosis involves direct visualization of T. pallidum via darkfield microscopy or detection of antibodies to T. pallidum via non-treponemal and treponemal tests. Penicillin is the treatment of choice for all stages of syphilis.

1. Syphilis

2. Syphilis
Caused by Treponema pallidum.
Transmission: sexual; maternal-fetal, and rarely by other means
Syphilis increases the risk of both transmitting and getting infected with HIV.

3. TREPONEMA

4. TREPONEMA
Pathogenic species
-T. pallidum subspecies pallidum
-T. pallidum subspecies pertenue
-T. pallidum subspecies endemicum
-T. carateum
Almost identical in their morphology, antigenic structure and in genetic composition

5. TREPONEMA PALLIDUM
Morphology: extremely thin and delicate
with tapering ends
Size: 6–14 μm × 0.2 μm
Spirals: 6–12 spirals at intervals of 1 μm
Motility: flexion extension, translatory,
and corkscrew motility
Endoflagella: About 3–4 flagella - motility
& highly antigenic

6. Microscopy
Dark ground or phase contrast microscope
Staining: Do not take up the ordinary stain.
-Fluorescence staining
-Sliver impregnation methods
Cultivation: Pathogenic treponemes cannot be grown in artificial culture media.
Maintained in rabbit testes. E.g,Nichols strain
Non-pathogenic Treponemes – grow in Smith Noguchi medium under strict anerobic
conditions

7. Antigens
1. Group-specific antigen: Protein antigen
- Present in all treponemes
- Antibodies detected using antigens of Reiter treponemes.
1. Species-specific antigen: Polysaccharide
- Antibodies detected by using specific T. pallidum antigens
1. Non-specific antigen: Heterophile antigen
- Antibody detected using beef heart antigen

8. PATHOGENESIS OF SYPHILIS
Mode of transmission:
-Venereal
-Non-venereal - direct contact, blood transfusion or transplacental
Spread: T. pallidum penetrates through mucosa or abraded skin  Enter lymphatics
and blood  systemic  primary lesion
Incubation period - Variable (9–90 days)
- Inversely proportional to the number of organisms inoculated

9. STAGES OF SYPHILIS
1. Primary
2. Secondary
3. Latent
Early latent
Late latent
4. Late or tertiary
May involve any organ, but main parts are:
Neurosyphilis
Cardiovascular syphilis
Late benign (gumma)

10. CLINICAL MANIFESTATIONS OF SYPHILIS
Primary Syphilis
Incubation period 9-90 days, usually ~21
days.
Develops at site of contact/inoculation.
Primary (or hard) chancre:
-Single painless papule ulcerated &
indurated
-Covered by thick exudate rich in
spirochetes
-Common sites – penis, cervix or labia
-Heals within 4–6 weeks

11. Regional (usually inguinal)
lymphadenopathy
-Painless firm, non-suppurative, and often
bilateral
-May persist for months
If acquired by non-venereal mode -
primary syphilis
-Direct contact → extragenital, usually on
the fingers
- Blood transfusion → primary chancre
does not occur Oral chancres

12. Secondary Syphilis
Develops 4–8 weeks after healing of
primary lesion
Skin and mucous membranes -Usually w
diffuse non-pruritic, indurated rash,
including palms & soles.

13. Secondary Syphilis
Condylomata lata- mucocutaneous papules
coalesce to form large pink to grey lesion in
warm moist intertriginous areas (such as
perianal region, vulva, and scrotum)
Mucous patches (superficial mucosal
erosions)
-30% of secondary syphilis patients develop
mucous patch
-slightly raised, oval area covered by a
grayish white membrane, with a pink base
that does not bleed.
-Highly infectious

14. Secondary Syphilis
May also cause:
Fever, malaise, headache, sore throat, myalgia, arthralgia, generalized
lymphadenopathy
Hepatitis (10%)
Renal: an immune complex type of nephropathy with transient nephrotic syndrome
Iritis or an anterior uveitis
Bone: periostitis
CSF pleocytosis in 10 - 30% (but, symptomatic meningitis is seen in <1%)

15. Latent Syphilis
Absence of clinical manifestations of syphilis with positive serological tests and
normal CSF findings.
Patients are still infectious - bloodstream or in utero
May lead to :
-Persistent lifelong infection (common)
-Development of late syphilis (rare)
-Spontaneous cure

16. Early latent:
• The first year after the resolution of primary or secondary lesions, or
• A reactive serologic test for syphilis in an asymptomatic individual who has had a
negative serologic test within the preceding year.
• Infectious.
Late latent:
Usually not infectious, except for the pregnant woman, who may transmit infection
to her fetus.
Latent Syphilis

17. -1/3 of untreated pts will proceed to tertiary syphilis
•Is the destructive stage of the disease.
•Lesions develop in skin, bone, & visceral organs (any organ).
•Can be crippling and life threatening
•Blindness, deafness, deformity, lack of coordination, paralysis, dementia may occur
•It is usually very slowly progressive, barring certain neurologic syndromes which may
develop suddenly due to endarteritis and thrombosis in the CNS
•Late syphilis is noninfectious.
Late or Tertiary Syphilis

18. Late or Tertiary Syphilis
The main types are:
Gumma (late benign syphilis): Locally destructive granulomatous lesions - bone and
skin
Neurosyphilis:
-Meningeal syphilis (meningitis)
- Meningovascular syphilis (vasculitis of arteries embolic stroke)
-General paresis of insane
-Tabes dorsalis
Cardiovascular syphilis: aneurysm of ascending aorta and aortic regurgitation

20. Congenital Syphilis
Transmission - at any stage of pregnancy
Fetal damage - after fourth month of gestation
Manifestations of congenital syphilis include:
Earliest manifestations : (within 2 years of age) & infectious
- Snuffles, mucocutaneous & bone changes, hepatosplenomegaly
Late congenital syphilis: (after 2 years) & non-infectious
-Interstitial keratitis, eighth-nerve deafness, bilateral knee effusions
Residual stigmata - Hutchinson’s teeth (notched central incisors), Mulberry molars,
Saddle nose, and saber shins

21. Residual stigmata
- Hutchinson’s teeth (notched central incisors), Mulberry molars, Saddle nose, and saber shins

22. LABORATORY DIAGNOSIS
Dark field Microscopy
VDRL, RPR
FTA-ABS, MHA-TP
Direct Fluorescent Antibody (DFA)

23. LABORATORY DIAGNOSIS OF SYPHILIS
Direct Microscopy
Dark Ground Microscopy (DGM)
-Slender, flexible, spirally coiled bacilli with tapering ends
Motility: Flexion-extension type, corkscrew motility, Soft
bending at right angle to the midpoint
Sensitivity of DGM - 80%
Detection limit of 104 bacilli/mL

25. LABORATORY DIAGNOSIS OF SYPHILIS
Direct Fluorescent Antibody Staining
- Distinct, sharply outlined, apple green
fluorescent bacilli
Sensitivity - 100% when smear made from fresh
lesions are examined

26. LABORATORY DIAGNOSIS OF SYPHILIS
Silver Impregnation Staining
Increase thickness
- Levaditi stain -tissue section
- Fontana stain – exudate smears
Cultivation- maintained by
subcultures in rabbit testes

27. Serology (Antibody Detection)
Non-treponemal tests: Detect non-specific reagin antibody by using cardiolipin
antigen derived from bovine heart
Treponemal tests: Detect species-specific antibody by using T. pallidum specific
antigen
Group-specific tests: Detect group or genus-specific antibody by using Reiter
treponemal strains possessing protein antigen present in all treponemes.

28. Standard Tests for Syphilis
Non-treponemal or Non-specific tests or STS (Standard Tests for Syphilis)
Detect reagin antibody using cardiolipin antigen extracted from beef heart
Cardiolipin antigen - diphosphatidyl glycerol
Reagin antibodies are IgG or rarely IgM type
-Slide flocculation tests - VDRL, RPR, USR, TRUST
-Wassermann test (e.g. of complement fixation test)
-Kahn test (e.g. of tube flocculation test

29. Venereal Disease Research Laboratory
(VDRL)
Widely used, simple and rapid
serological test
VDRL antigen - cardiolipin antigen
to which cholesterol and lecithin
are added
Slide Flocculation test

30. Venereal Disease Research Laboratory
(VDRL)
Qualitative test: Inactivated serum + a drop of VDRL antigen rotated at 180 rpm
for 4 minutes in a VDRL rotator  examined under microscope
- Non-reactive: Uniformly distributed fusiform crystals
- Reactive: Medium to large clumps
Quantitative test: Test performed with serial dilutions (1:2, 1:4, 1:8 and so on) of
serum done with 0.9% saline
VDRL-CSF:No preheating of CSF is needed

31. VDRL v/s RPR
VDRL RPR
Results read microscopically - clumps
are smaller
Results read macroscopically - Finely
divided carbon particles coated
cardiolipin antigens are used so that
larger visible clumps are formed
Antigen, once reconstituted, should
be used within 24 hours
EDTA is used as stabilizer; hence RPR
antigen can be stored longer (up to 6
months at 4-100C)
Preheating of serum is required to
remove non specific inhibitors
Preheating of serum is not required as
choline chloride is used to remove
inhibitors

32. VDRL v/s RPR
VDRL RPR
Blood, plasma, serum, and CSF can be
tested
Blood, plasma and serum can be tested
but not CSF
Rotation of slide is done for 4 mins Rotation of card is done for 8 mins
Sensitivity in primary syphilis is 78% Sensitivity in primary syphilis is 86%
It is cheaper; one vial of VDRL antigen
can be used for 250 tests. It is preferred
for field studies and for antenatal
screening
RPR is expensive than VDRL. It is
preferred when sample load is less.

33. Other Reagin Antibody Tests
Unheated Serum Reagin Test (USR) is similar to VDRL except for:
-EDTA - antigen stabilizer  daily preparation of antigen is eliminated
-Choline chloride - inhibit the non-specific inhibitors in serum  pre-heating of
serum is not needed
Toluidine Red Unheated Serum Test (TRUST)
-Modified RPR test where toluidine red pigment particles
-Does not require microscope for examination

34. Advantages of Non-treponemal Tests
To monitor the response to treatment
- Reagin tests usually become negative 6–18 months after the effective treatment
Neurosyphilis: VDRL detects CSF antibodies
Detectable 7–10 days after the appearance of primary chancre (or 3–5 weeks after
acquiring the infection)
Sensitivity: Varies from 78 to 85% in primary stage, 100% in secondary stage and 95–
98% in latent stage

35. Disadvantages of Non-treponemal
Tests
Biological false-positive (BFP) reactions: Positive non-treponemal tests, with negative
treponemal tests, in absence of syphilis and no technical faults. BFP Antibodies - 1% of
normal sera, IgM type
Conditions - lepromatous leprosy, relapsing fever, malaria, tropical pulmonary
eosinophilia, viral hepatitis, infectious mononucleosis, HIV, pregnancy and IV drug
abusers
Prozone phenomena
Sensitivity of non-treponemal tests is low in late stage
Non-treponemal tests are used as screening tests

36. Treponemal or Specific Tests
T. pallidum Immobilization (TPI) test
-Principle: patient’s antibody and complement to immobilize the live
actively motile T.pallidum (Nichols strain) - observed under dark ground
microscope

37. Treponemal or Specific Tests
Fluorescent Treponemal Antibody-Absorption Test (FTA -ABS)
-Uses killed T.pallidum, indirect fluorescent antibody technique
-Patient’s serum diluted with an extract of nonpathogenic Reiter treponemes to
remove group specific treponemal antibodies  layered on a slide previously
coatedwith killed T. pallidum  Serum antibodies bound to T. pallidum can be
detected by addition of fluorescent labeled anti-human immunoglobulin
examined under fluorescent microscope

38. Treponemal or Specific Tests
IgM-FTA-ABS test
Advantages: Highly sensitive and specific in all stages of syphilis
-First serological test to be positive following infection
-Detects CSF antibodies
-Disadvantage: False positive in other treponemal diseases (pinta, yaws..) and other
spirochete diseases (Lyme, leptospirosis…)
-Remains reactive for lifein most, despite adequate therapy. Only 15-25 % of those
treated for primay syphilis may turn negative by 2-3 yrs.

39. Treponemal or Specific Tests
T. pallidum Hemagglutination Assay (TPHA)
- Tanned sheep RBCs coated with T.pallidum antigens
-Reactive result: Smooth mat of agglutinated cells in microtiter plate
-Nonreactive result: Compact button in the center of the well
Quantitation - done by serial dilution of patient’s sera
Advantages: Affordable, easy to perform, available as commercial kit and no special
equipment is needed, detects CSF antibodies
- Sensitivity and specificity of TPHA are excellent

40. Treponemal or Specific Tests
Enzyme Immunoassays
-ELISA specific to IgG and IgM, ™
They have excellent sensitivity and
specificity
Western Blot
-Detects IgG and IgM antibodies separately, highly sensitive and specific
Group-specific Test
- Reiter’s protein complement fixation test (RP-CFT)
Molecular Methods - PCR-based techniques

41. Diagnosis of congenital syphilis
Definitive diagnosis:
Demonstration of T. pallidum by DGM of umbilical cord, placenta, nasal
discharge, or skin lesion material
Presumptive diagnosis:
-Infant born to a mother who had syphilis at the time of delivery regardless
of findings in the infant
-Reactive treponemal test in infant

42. Diagnosis of congenital syphilis
One of the following additional criteria:
-Clinical signs/symptoms of congenital syphilis
-Abnormal CSF findings without other cause
-Reactive VDRL-CSF test
-Reactive IgM antibody test specific for syphilis (IgM FTA ABS or IgM
ELISA).
Presence of specific IgM in neonatal serum confirms the diagnosis

43. Syphilis and HIV
Both syphilis and HIV affect each other’s pathogenesis
Problems in the diagnosis of syphilis in HIV infected people are:
-Confusing clinical picture, Lack of serologic response
-Unusually high titers in non-treponemal tests
-Failure of non-treponemal test titers to decline even after treatment
-Disappearance of treponemal test reactivity over time

44. Treatment Syphilis
Penicillin is the drug of choice for all the stages of syphilis
-Primary, secondary, or early latent syphilis: single dose of Penicillin G
-Late latent CVS or benign tertiary stage: penicillin G is given single dose weekly for 3
weeks
-Alternative drug is used in patients with penicillin allergy:
-Primary, secondary, latent, CVS or benign tertiary syphilis—tetracycline
-Neurosyphilis or pregnancy or associated HIV—desensitization to penicillin

45. Evaluation after Treatment
Non-treponemal tests
For primary and secondary syphilis:
-at least fourfold decline in the titer by the third or fourth month and an eightfold
decline in the titer by sixth to eighth month
Latent or late syphilis, or patients with multiple episodes of syphilis:
-gradual decline in titer, low titers may persist for years

46. NON-VENEREAL
TREPONEMATOSES

47. NON-VENEREAL TREPONEMATOSES
Feature Venereal
Syphilis
Yaws Endemic
Syphilis
Pinta
Agent T. pallidum T. pertenue T. endemicum T.carateum
Mode of
transmission
Sexual,
Transplacental
Blood
Skin-to-skin Household
contacts:
kissing,
sharing
utensils or
insect vector
Skin-to-Skin
Age Adulthood Early
childhood
Early
childhood
Late
childhood

48. NON-VENEREAL TREPONEMATOSES
Feature Venereal
Syphilis
Yaws Endemic
Syphilis
Pinta
Primary lesion Chancre-
painless
non-
indurated
Lymphadenop
athy
Papilloma,
often
ulcerative
Lymphadenop
athy
Rarely seen Non
ulcerating
pruritic
papule
Site of lesion Genital, oral,
anal
Extremities Oral Extremities,
face

49. NON-VENEREAL TREPONEMATOSES
Feature Venereal
Syphilis
Yaws Endemic
Syphilis
Pinta
Secondary
lesions
Skin rashes
Mucosal
patches
Condylomata
lata
Skin lesions-
macular or
papular
Periostitis
Oral mucous
patches
Periostitis,
Lymphadenop
athy
Pintides,
Pigmented &
pruritic
Relapses 25% Common Unknown None

50. NON-VENEREAL TREPONEMATOSES
Feature Venereal
Syphilis
Yaws Endemic
Syphilis
Pinta
Late
complications
Gummas,
CVS and CNS
lesion
Destructive gummas of skin,
bone, cartilage
Destruction of the nose,
maxilla, palate, and pharynx is
termed as gangosa
Non
destructive,
dyschromic
macule

51. THANK YOU