1. Overview of Reverse Sequence Syphilis Testing u Presented May 2012 at Oregon Epidemiologist Conference by Doug Harger, Manager, STD Prevention and Control Program, HIV/STD/TB Program, Center for Public Health Practice, Oregon Health Division –971-673-0181; douglas.r.harger@state.or.us u Modifed July 23, 2012

2. Syphilis Testing: Something New? u There are 2 classes of blood test for syphilis

3. Syphilis Testing: Something New? u (1) non-treponemal, cardiolipin antibody tests—used for screening asymptomatic people and assessing response to treatment –Rapid Plasma Reagin (RPR) –Venereal Disease Research Laboratory test (VDRL)

4. Syphilis Testing: Something New? u (2) Treponemal tests—in US generally used as confirmatory tests but EIA and CIA sometimes used for screening. –Fluorescent treponemal antibody absorbtion test (FTA- ABS) –Treponema Pallidum-Particle Agglutination Test (TP- PA) –Microhemaglutination Treponema Pallidum (MHA- TP) –Enzyme Immunoassay (EIA) –Chemiluminescent Immunoassay (CIA),

5. Syphilis Testing Points u If an individual has newly acquired syphilis, a treponemal test generally is positive before the non-treponemal test. u Example: a person has a primary syphilitic lesion for 5 days – the FTA may be reactive and the RPR non reactive.

6. Traditional Sequence Testi ng u non-treponemal test first, e.g., RPR, if non-reactive, generally no further testing; u If RPR is reactive, the specimen is reflexed for a treponemal test, e.g., FTA, TP-PA.

7. Reverse Sequence Syphilis Testing u Testing serum for syphilis first with a confirmatory test, generally a treponemal EIA (enzyme immunoassay), or chemiluminescence immunoassay (CIA). u If the treponemal EIA result is non-reactive the result is reported as negative – no further testing generally recommended.

8. Reverse Sequence Syphilis Testing u If the treponemal EIA or CIA is reactive, the specimen is reflexed for an RPR. u If the RPR is reactive, the interpretation is past or present syphilis infection. If no treatment history—treat

9. Reverse Sequence Syphilis Testing u If the RPR is non-reactive after a positive EIA or CIA, the specimen should be tested reflexively with another treponeme specific test, ideally TP-PA. If the TP-PA is non- reactive, the EIA is likely a false positive. u If the TP-PA is reactive, likely represents and old infection, or possibly a very new infection.

10. Why Switch to EIA/CIA? u Automated u Lower costs u No false negatives due to prozone reaction u Objective results u May be useful for dx of early primary syphilis—positive earlier in infection than non-treponemal tests

11. Limitations of EIA/CIA u Cannot distinguish between new/active disease & old disease - treated or untreated. u Confusion about management of patients with discrepant serology – positive EIA/CIA and a negative RPR

12. Recent Examples u Patient presents with a rash, EIA is highly reactive > 8.0, reflexed RPR is 1:128; patient is treated as secondary syphilis. u Routine draw on a patient, EIA is reactive, reflexed RPR is non-reactive, TP-PA is non-reactive, the EIA result is considered false positive, patient not infected.

13. CDC Recommendations u “CDC continues to recommend the traditional syphilis screening algorithm …, however, if reverse sequence screening is used, reactive sera by a treponemal test should be tested reflexively with a quantitative non-treponemal test.” For example, a RPR.