What is the risk for false-positive (BFP) test results in the diagnosis of neurosyphilis?

Updated: Jul 17, 2018
  • Author: Richard P Knudsen, MD, FAAN, FAAP; Chief Editor: Niranjan N Singh, MBBS, MD, DM, FAHS, FAANEM  more...
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The cardiolipin antigen used in the nontreponemal tests is found in other tissues, resulting in false-positive serologic test results. These false-positive results can be found in persons with nonvenereal treponemal infections (eg, yaws, pinta, bejel), those who have received certain immunizations (eg, smallpox), pregnant women, patients with acute or chronic infections (eg, infectious mononucleosis, malaria), or those with certain chronic conditions (eg, aging, intravenous drug usage, autoimmune disorders, malignancy). False-positive RPR test results are identified by excluding syphilis with a nonreactive treponemal test. Biological false-positive CSF reagin test results may result from tuberculosis or pyogenic or aseptic meningitis. However, even with sufficient treatment, patients sometimes have a persistent low-level positive nontreponemal test, which is referred to as a serofast reaction.

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