Syphilis Testing

A syphilis test is done to detect if a person is positive for the bacteria Treponema pallidum. Since the symptoms of syphilis are common for any disease, a syphilis test is done to verify the infection.

There are two types of blood tests that diagnose a syphilis infection.

  • syphilis testingTreponemal antibody tests: These tests detect antibodies that specifically fight the bacteria T. pallidum. Once treponemal antibodies are developed by the body of a syphilis infected person, these antibodies stay in the blood forever even if syphilis is already successfully treated. On the other hand, non-treponemal antibodies will stay in the blood of an infected person for about three years after treatment. Thus, treponemal antibody tests are best used to detect an untreated active syphilis infection. The following are the different treponemal antibody tests:
    • Fluorescent treponemal antibody absorption (FTA-ABS) – this test is mostly used to detect syphilis bacteria for the first three to four weeks after an exposure. This test is done by taking a blood or fluid sample from the infected area of the patient.
    • Treponema pallidum particle agglutination assay (TPPA) – this test is more accurate than FTA-ABS and is only done by taking blood sample.
    • Microhemagglutination assay (MHA-TP) – this test is done after a test has detected positive for syphilis, but this is not commonly performed now.
    • Immunoassays (AIA) – this is one of the most developed testing methods for syphilis and is more convenient.
  • Nontreponemal antibody tests: These tests detect antibodies that fight not only syphilis bacteria but also other diseases. Nontreponemal antibody tests are very sensitive but do not specifically detect syphilis bacteria only. Thus, these tests are only done to confirm an initial treponemal antibody test. Nontreponemal antibody tests are the following:
    • Rapid Plasma Reagin test (RPR) – this test is mostly used to monitor treatment for syphilis and measure the titer of the antibodies.
    • Venereal Disease Research Laboratory (VDRL): this test is mostly done to detect neurosyphilis