Virology / Serology: Syphilis FAQs
Frequently Asked Questions
- Can we download the Syphilis Serology Form DHHS #3446 from this site and use it to request both RPR and confirmatory testing?
Yes. The DHHS Syphilis Serology Form #3446 (PDF, 88 KB) has been updated to include the option for ordering confirmatory testing. It is no longer necessary to use a separate DHHS Special Serology Form #3445 to order confirmatory testing. Please use white paper only.
- Why are the FTA-ABS and VDRL tests no longer available at the State Laboratory?
In an effort to conserve limited resources, reviews were conducted to evaluate the necessity of offering these two low-volume assays. Studies showed an agreement correlation of 99.9% between the TP-PA (the confirmatory test in use at the time) and FTA-ABS assays in our laboratory. The VDRL non-treponemal screening assay for suspected cases of neurosyphilis was mostly used by private health care providers and was of limited public health value. These tests are commercially available from private sector reference laboratories in North Carolina and elsewhere.
- How long can we hold serum for syphilis testing before shipping (i.e., during courier interruptions due to adverse weather)?
Serum specimens for syphilis serology testing, if aseptically collected and maintained, are stable at ambient temperature for several days or refrigerated (4-8 ºC) for up to four weeks.
- What is the turnaround time for syphilis serology test results?
RPR test results are available within three working days after receipt of specimen in the laboratory. TREP-SURE EIA test results are available within four working days after specimen receipt.
- Can we request a RPR titer if the RPR result is Non-Reactive?
No. RPR titers can only be performed if the RPR test is Reactive.
- Can a TREP-SURE EIA result be falsely positive?
False positive results may occur in otherwise normal or healthy persons (biological false positives), or in patients with underlying diseases such as infectious mononucleosis, leprosy, autoimmune diseases, or drug addiction. The TREP-SURE EIA may also be reactive in patients from geographic areas where yaws or pinta is endemic.
- Can the RPR and TREP-SURE EIA tests be performed on plasma?
Serum is the most appropriate specimen for both the RPR and TREP-SURE EIA tests.
- Which screening test is more accurate, RPR or TRUST?
Both RPR and TRUST are non-treponemal standard status diagnostic tests for syphilis, with similar levels of sensitivity and specificity in qualitative assays. However, since endpoint titers may vary between these two tests, the same test used in the initial testing should be used to monitor treatment.