Nontreponemal Tests:
VDLR and RPR may be falsely negative for up to four weeks after the appearance of a chancre and cannot reliably rule out primary<unk> 
Rapid Plamsa Reagin (RPR)*
Faster and easier to perform
Venereal Disease Research Laboratory (VDRL)*
Standard for CSF examination
Toludine Red Unheated Serum Test (TRUST)
Faster and easier to perform
Standard for CSF examination
Most commonly in the ED, the VDRL and RPR will be the ordered screening test
Treponemal Test:
Fluorescent treponemal antibody absorption (FTA-ABS)
Microhemagglutination test for antibodies to Treponema pallidum (MHA-TP)
Treponemal pallidum particle agglutination assay (TP-PA)
Treponema pallidum enzyme immunoassay (TP-EIA)
CSF
Pleocytosis (>5 WBC/uL), increased protein (>45mg/dL) or VDRL reactivity
May be confounded by HIV infection
CSF VDRL test is highly specific but is relatively insensitive. Further testing with treponemal antibodies may be necessary.
HIV-infected patients
All newly diagnosed HIV patients should be tested for<unk>  and vice versa
RPR titer and CD4 count can be used to identify patients at higher risk for neurosyphilis for lumbar puncture
Syphilis
Ulcerative STDs
Smallpox
Proctitis
Leprosy
Genital Herpes
Rubella
Chancroid