Venereal Disease Research Laboratory test
Encyclopedia
The Venereal Disease Research Laboratory test or VDRL is a blood test for syphilis and was developed by the former Venereal Disease Research Laboratory, now the Treponemal Pathogenesis and Immunology Branch, of the United States Public Health Service
. The VDRL type test was invented before World War I
, with its first iteration being that developed by August Paul von Wasserman with the aid of Albert Neisser in 1906.
) test uses the same antigen as the VDRL, but in that test it has been bound to several other molecules including a carbon particle to allow visualization of the flocculation reaction without the need of a microscope.
The (VDRL) is a nontreponemal
serological screening for syphilis
that is also used to assess response to therapy, to detect CNS involvement, and as an aid in the diagnosis of congenital syphilis. The basis of the test is that an antibody produced by a patient with syphilis reacts with an extract of ox heart (diphosphatidyl glycerol). It therefore detects anti-cardiolipin antibodies
(IgG, IgM or IgA), visualized through foaming of the test tube fluid, or "flocculation".
Many other medical conditions can produce false positive results, including some viruses (mononucleosis, hepatitis), drugs, pregnancy, rheumatic fever, rheumatoid arthritis, lupus, and leprosy.
The syphilis anti-cardiolipin antibodies are beta-2 glycoprotein independent, where as those that occur in the antiphospholipid antibody syndrome (associated to lupus for example) are beta-2 glycoprotein dependent, and this can be used to tell them apart in an ELISA
assay. This test is very useful as the trend of titres are correlated to disease activity (i.e. falling titres indicate successful treatment). It has a very good sensitivity for syphilis, except in late tertiary form.
) test, Treponema pallidum hemagglutination assays (TPHA and MHA-TP), Treponema pallidum particle agglutination assay (TP-PA), and the Toluidine red unheated serum test (TRUST) which may be used to confirm a positive VDRL result. These tests are more specific for syphilis than non-treponemal tests and, in the presence of a positive test, more likely indicate active infection. Unfortunately other treponemal infections such as yaws
, bejel
and pinta
and possibly nonpathogenic commensal treponemes can result in a positive.
However it must be noted that all treponemal specific tests will remain positive for life once a person has been infected with syphilis, even if syphilis has been adequately treated. Therefore, these types of tests cannot be used to monitor the treatment of syphilis.
automated RPR test(ART)is available for large scale tests.
United States Public Health Service
The Public Health Service Act of 1944 structured the United States Public Health Service as the primary division of the Department of Health, Education and Welfare , which later became the United States Department of Health and Human Services. The PHS comprises all Agency Divisions of Health and...
. The VDRL type test was invented before World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...
, with its first iteration being that developed by August Paul von Wasserman with the aid of Albert Neisser in 1906.
History
The VDRL test, as it is largely still done today, was developed in 1946 by Harris, Rosenberg, and Riedel.Mechanism
The RPR (Rapid Plasma ReaginRapid Plasma Reagin
Rapid Plasma Reagin refers to a type of test that looks for non-specific antibodies in the blood of the patient that may indicate that the organism that causes syphilis is present...
) test uses the same antigen as the VDRL, but in that test it has been bound to several other molecules including a carbon particle to allow visualization of the flocculation reaction without the need of a microscope.
The (VDRL) is a nontreponemal
Nontreponemal
Nontreponemal tests refer to a class of syphilis diagnostics that detect infection by indirect markers of infection. Nontreponemal Tests detect biomarkers that are released during cellular damage that occurs from the syphilis spirochete...
serological screening for syphilis
Syphilis
Syphilis is a sexually transmitted infection caused by the spirochete bacterium Treponema pallidum subspecies pallidum. The primary route of transmission is through sexual contact; however, it may also be transmitted from mother to fetus during pregnancy or at birth, resulting in congenital syphilis...
that is also used to assess response to therapy, to detect CNS involvement, and as an aid in the diagnosis of congenital syphilis. The basis of the test is that an antibody produced by a patient with syphilis reacts with an extract of ox heart (diphosphatidyl glycerol). It therefore detects anti-cardiolipin antibodies
Anti-cardiolipin antibodies
Anti-cardiolipin antibodies are antibodies often directed against cardiolipin and found in several diseases including syphilis, antiphospholipid syndrome, livedoid vasculitis, vertebrobasilar insufficiency, Behçet's syndrome, idiopathic spontaneous abortion, and systemic lupus erythematosus. They...
(IgG, IgM or IgA), visualized through foaming of the test tube fluid, or "flocculation".
Many other medical conditions can produce false positive results, including some viruses (mononucleosis, hepatitis), drugs, pregnancy, rheumatic fever, rheumatoid arthritis, lupus, and leprosy.
The syphilis anti-cardiolipin antibodies are beta-2 glycoprotein independent, where as those that occur in the antiphospholipid antibody syndrome (associated to lupus for example) are beta-2 glycoprotein dependent, and this can be used to tell them apart in an ELISA
ELISA
Enzyme-linked immunosorbent assay , is a popular format of a "wet-lab" type analytic biochemistry assay that uses one sub-type of heterogeneous, solid-phase enzyme immunoassay to detect the presence of a substance in a liquid sample."Wet lab" analytic biochemistry assays involves detection of an...
assay. This test is very useful as the trend of titres are correlated to disease activity (i.e. falling titres indicate successful treatment). It has a very good sensitivity for syphilis, except in late tertiary form.
Other tests
There are a number of treponemal-specific tests such as the Fluorescent treponemal antibody-absorption (FTA-ABSFTA-ABS
FTA-Abs is a treponemal test for syphilis. Using antibodies specific for the Treponema pallidum species, such tests are more specific than non-treponemal testing such as VDRL. In addition, FTA-Abs turns positive earlier and remains positive longer than VDRL. Other treponemes, such as T...
) test, Treponema pallidum hemagglutination assays (TPHA and MHA-TP), Treponema pallidum particle agglutination assay (TP-PA), and the Toluidine red unheated serum test (TRUST) which may be used to confirm a positive VDRL result. These tests are more specific for syphilis than non-treponemal tests and, in the presence of a positive test, more likely indicate active infection. Unfortunately other treponemal infections such as yaws
Yaws
Yaws is a tropical infection of the skin, bones and joints caused by the spirochete bacterium Treponema pallidum pertenue...
, bejel
Bejel
Bejel, or endemic syphilis, is a chronic skin and tissue disease caused by infection by a subspecies of the spirochete Treponema pallidum....
and pinta
Pinta
-External links:* List of crew members on the Pinta....
and possibly nonpathogenic commensal treponemes can result in a positive.
However it must be noted that all treponemal specific tests will remain positive for life once a person has been infected with syphilis, even if syphilis has been adequately treated. Therefore, these types of tests cannot be used to monitor the treatment of syphilis.
automated RPR test(ART)is available for large scale tests.