Next generation open access visualization of neuroanatomy through 3D modeling and 3D printing.

Syphilis is a sexually and vertically transmitted infection caused by the spirochete subspecies . Untreated infections can progress through four clinical stages with sometimes nonspecific symptoms that can be mistaken for other diseases. Severe clinical manifestations include neurosyphilis, ocular syphilis, and cardiovascular syphilis, and untreated maternal infection frequently results in pregnancy loss or significant birth defects. Although syphilis is effectively treated with benzathine penicillin G, challenges inherent to both clinical and laboratory diagnosis have hampered public health efforts to control the spread of disease. The currently recommended approach for the diagnosis of syphilis involves algorithmic use of indirect serological tests, and additional direct methods such as darkfield microscopy, molecular assays, and immunohistochemistry are applied in specific settings. Serologic assays are categorized as treponemal or nontreponemal (also referred to as lipoidal). Nontreponemal tests such as the rapid plasma reagin (RPR) detect antibodies produced in response to antigens such as cardiolipin, phosphatidylcholine, and cholesterol originating from both and damaged host tissue during infection. Sequential RPR titers can be compared to assess for possible re-infection with rising titers or a successful treatment response with decreasing titers over time. Treponemal tests, including enzyme immunoassays (EIA), chemiluminescence immunoassays (CMIA), and particle agglutination assays (TPPA), detect antibodies specific for In contrast to nontreponemal antibodies, treponemal antibodies typically remain detectable for life even after successful antibiotic treatment. Both classes of serological tests have known limitations that must be considered when interpreting results. Serological tests can yield false negative results, particularly in cases of early primary infection. Biological false positive results can occur due to nontreponemal test cross-reactivity in patients with other conditions including autoimmune diseases, other bacterial or viral infections, and in older or pregnant indivduals. Additionally, treponemal tests exhibit lower positive predictive value when the prevalence of infection is low. As no single assay is sufficiently sensitive and specific to be used as a standalone test, algorithmic testing is recommended. The traditional or forward algorithm for testing begins with a nontreponemal test with reflexive performance of a confirmatory treponemal test when positive. Alternatively, an increasing number of laboratories utilize a reverse algorithm that begins with a treponemal test performed on an automated platform, with positive results confirmed by a nontreponemal test. An additional treponemal test, ideally using antigens different from the ones tested in the initial step, is used as a third step as needed to arbitrate discrepant results. Previously infected patients can have detectable treponemal antibodies for life, regardless of treatment status. Test results must be considered together with a patient’s symptoms, exposures, and treatment history, and in some cases retesting is warranted.