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The rapid plasma reagin (RPR) 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. Many other medical conditions can produce false positive results, including some viruses ...
Replacement tests such as the VDRL test and the RPR test, initially based on flocculation techniques (Hinton), have been shown to produce far fewer false positive results. [citation needed] Indeed, the "biologic false positives" of modern tests usually indicate a serious alternate condition, often an autoimmune disease.
This reaction is the foundation of “nontreponemal” assays such as the VDRL (Venereal Disease Research Laboratory) test and Rapid Plasma Reagin (RPR) test. Both these test are flocculation type tests that use an antigen-antibody interaction. The complexes remain suspended in solution and therefore visible due to the lipid based antigens.
Another test often used to screen for syphilis is the Venereal Disease Research Laboratory (VDRL) slide test. However, the RPR test is generally preferred due to its ease of use. Other types of tests are being evaluated as possible alternatives to standard manual RPR testing. One of these alternatives is a fully automated RPR syphilis analyzer. [3]
The VDRL test of the CSF is a common test for making a diagnosis of neurosyphilis. A positive VDRL test in the presence of neurological symptoms is sufficient to confirm a diagnosis of neurosyphilis. [4] However, a negative VDRL result does not rule out neurosyphilis.
Since the antibodies do not bridge between antigens, no agglutination occurs. Because no agglutination occurs, the test is interpreted as negative. In this case, the result is a false negative. The range of relatively high antibody concentrations within which no reaction occurs is called the prozone. [5]
The fluorescent treponemal antibody absorption (FTA-ABS) test is a diagnostic test for syphilis.Using antibodies specific for the Treponema pallidum species, such tests would be assumed to be more specific than non-treponemal testing such as VDRL but have been shown repeatedly to be sensitive but not specific for the diagnosis of neurosyphilis in cerebrospinal fluid (CSF).
They include the venereal disease research laboratory (VDRL; requires microscopy) and rapid plasma reagin (RPR; naked-eye result) tests, both of which flocculate patient-derived antibodies with antigens. [2] Serological tests cannot distinguish yaws from the closely related syphilis; [2] no test distinguishing yaws from syphilis is widely ...