School Papers

Mother by the infection, as well as to

Mother to child transmission in syphilis
is an important preventable cause of maternal morbidity and
new
born morbidity and mortality. Untreated maternal syphilis leads to adverse outcomes in 50% of
cases like spontaneous
abortions,
stillbirths, low birth weight babies and congenital syphilis(1).

 

Syphilis is caused by the spirochete Treponema
pallidum. The infection is systemic
and the disease is
characterized by periods of latency. These features, together with
the fact that
T. Pallidum cannot be isolated in culture, mean
that serologic techniques play a major role in the diagnosis and
follow-up

of treatment for syphilis(3).
As a result of routine serologic
screening for syphilis
in antenatal
clinics and treatment with penicillin,
congenital syphilis
is now rare worldwide
but
is still common in India
with a prevalence of 0.38% in pregnant women(2). Pregnancy often masks
the early signs of
syphilis but the mother
has serological evidence of treponemal infection. Vertical
transmission most commonly takes place after
17
weeks of gestation, therefore treatment must be started by 17 weeks (4)

 

Serological
tests for syphilis
can be divided in
two major
groups, the nontreponemal and the treponemal tests.
The nontreponemal tests or standard tests for syphilis detect antibodies
against the phospholipid hapten cardiolipin,
in complex with lecithin and cholesterol which
is used either in a complement fixation test (Wassermann test) or in agglutination tests such as the
Venereal Disease
Research Laboratory (VDRL) test, the automated reagin test (ART), or
the
rapid plasma reagin test.
The serological diagnosis
of
syphilis still depends to a large extent on the results of a nontreponemal
test, supplemented when
necessary by a confirmatory treponemal antibody test (6).
The nontreponemal tests are extremely valuable
for
screening purposes and may have even
higher specificities for syphilis than the treponemal tests (5).Currently, screening for syphilis is
done using VDRL
slide flocculation test during the first antenatal visit.
This test detects anti-lipid IgG
and IgM formed in
response to lipoidal
material
released from the
cells damaged by
the infection, as well as

to lipids on the surface of T. pallidum(4). Though
inexpensive and easy,
it shows positivity only 4 to 6 weeks after exposure (7). Hence, sensitivity is less in primary
syphilis
(7) and with patients on
antibiotic therapy. Overtime 25% patients
with untreated
latent and tertiary syphilis test
negative (3). Also since cardiolipin is a non-specific antigen, antibodies other than those against syphilitic antigens will also show positivity.
These reactions are
called biological
false positive reactions. The prozone phenomenon, occuring in
2% of infected persons,
especially in secondary syphilis
and pregnancy may lead to false negatives (3) and serial dilutions
are time consuming in
a high volume laboratory. The nontreponemal tests presently used are not ideal.
None of the tests used today is
able to distinguish
between immunoglobulin G (IgG) and IgM without previous separation of serum. These
samples must be confirmed with
specific tests (6).

 

Specific
tests measure antibodies
against specific T. Pallidum antigens.
The need for skilled
professionals and subjective results in Treponema
pallidum particle
agglutination assay (3), living
pathogenic T.
pallidum in Treponema pallidum Immobilization test .Variable interpretation in
fluorescent treponemal antibody absorption test(8) combined with
absence of fluorescent
microscopes(9) in resource poor settings has given the enzyme linked immunosorbent assay an
important
place in syphilis screening. This specific test
detects IgM and IgG using recombinant
proteins or treponemal
antigens extracted from T.
pallidum. This test becomes positive earlier than non treponemal
tests. Patients on antibiotic therapy and patients
with latent and tertiary syphilis
also test positive. Therefore this test may be
used to screen pregnant women.
Since treated patients also show positivity, this must be followed by a nontreponemal
test
for active infection.
Unlike

nontreponemal tests, the number of false negatives is less.
The
false positives can be ruled out with
VDRL test. This project aims
to
confirm this reverse algorithm for screening of syphilis in pregnant women
and
to compare its performance with VDRL test.Mother to child transmission in syphilis
is an important preventable cause of maternal morbidity and
new
born morbidity and mortality. Untreated maternal syphilis leads to adverse outcomes in 50% of
cases like spontaneous
abortions,
stillbirths, low birth weight babies and congenital syphilis(1).

 

Syphilis is caused by the spirochete Treponema
pallidum. The infection is systemic
and the disease is
characterized by periods of latency. These features, together with
the fact that
T. Pallidum cannot be isolated in culture, mean
that serologic techniques play a major role in the diagnosis and
follow-up

of treatment for syphilis(3).
As a result of routine serologic
screening for syphilis
in antenatal
clinics and treatment with penicillin,
congenital syphilis
is now rare worldwide
but
is still common in India
with a prevalence of 0.38% in pregnant women(2). Pregnancy often masks
the early signs of
syphilis but the mother
has serological evidence of treponemal infection. Vertical
transmission most commonly takes place after
17
weeks of gestation, therefore treatment must be started by 17 weeks (4)

 

Serological
tests for syphilis
can be divided in
two major
groups, the nontreponemal and the treponemal tests.
The nontreponemal tests or standard tests for syphilis detect antibodies
against the phospholipid hapten cardiolipin,
in complex with lecithin and cholesterol which
is used either in a complement fixation test (Wassermann test) or in agglutination tests such as the
Venereal Disease
Research Laboratory (VDRL) test, the automated reagin test (ART), or
the
rapid plasma reagin test.
The serological diagnosis
of
syphilis still depends to a large extent on the results of a nontreponemal
test, supplemented when
necessary by a confirmatory treponemal antibody test (6).
The nontreponemal tests are extremely valuable
for
screening purposes and may have even
higher specificities for syphilis than the treponemal tests (5).Currently, screening for syphilis is
done using VDRL
slide flocculation test during the first antenatal visit.
This test detects anti-lipid IgG
and IgM formed in
response to lipoidal
material
released from the
cells damaged by
the infection, as well as

to lipids on the surface of T. pallidum(4). Though
inexpensive and easy,
it shows positivity only 4 to 6 weeks after exposure (7). Hence, sensitivity is less in primary
syphilis
(7) and with patients on
antibiotic therapy. Overtime 25% patients
with untreated
latent and tertiary syphilis test
negative (3). Also since cardiolipin is a non-specific antigen, antibodies other than those against syphilitic antigens will also show positivity.
These reactions are
called biological
false positive reactions. The prozone phenomenon, occuring in
2% of infected persons,
especially in secondary syphilis
and pregnancy may lead to false negatives (3) and serial dilutions
are time consuming in
a high volume laboratory. The nontreponemal tests presently used are not ideal.
None of the tests used today is
able to distinguish
between immunoglobulin G (IgG) and IgM without previous separation of serum. These
samples must be confirmed with
specific tests (6).

 

Specific
tests measure antibodies
against specific T. Pallidum antigens.
The need for skilled
professionals and subjective results in Treponema
pallidum particle
agglutination assay (3), living
pathogenic T.
pallidum in Treponema pallidum Immobilization test .Variable interpretation in
fluorescent treponemal antibody absorption test(8) combined with
absence of fluorescent
microscopes(9) in resource poor settings has given the enzyme linked immunosorbent assay an
important
place in syphilis screening. This specific test
detects IgM and IgG using recombinant
proteins or treponemal
antigens extracted from T.
pallidum. This test becomes positive earlier than non treponemal
tests. Patients on antibiotic therapy and patients
with latent and tertiary syphilis
also test positive. Therefore this test may be
used to screen pregnant women.
Since treated patients also show positivity, this must be followed by a nontreponemal
test
for active infection.
Unlike

nontreponemal tests, the number of false negatives is less.
The
false positives can be ruled out with
VDRL test. This project aims
to
confirm this reverse algorithm for screening of syphilis in pregnant women
and
to compare its performance with VDRL test.