Diagnosis of Syph: Visualized by immunofluorescence or dark-field microscopy; serology is important – two types of antibodies:
Examples include Venereal Disease Research Lab (VDRL), Rapid plasma Reagin (RPR), Automated Reagin Test (ART), or Recombinant Antigen Test (ICE)
Specific tests for treponemal antibody are more expensive; earliest antibodies bind to spirochetes: these tests are more specific and positive earlier; usually remain positive for life, but positive n patients with other treponemal diseases and may be positive in Mono, RF, Lupus, Leprosy, Lime, and Drug users.
Any answer with treponemes is used to syphilus only and is very specific. That only leaves cardiolipin, which is also elevated in SLE; this is why its sensitive but not specific in Syph.
Non-treponemal tests are sensitive, but not specific - RPR, VRDL