Nontreponemal tests look for reagin antibodies. Doctors use them as initial screening tests. These directly look for the syphilis bacteria or for antibodies for that bacteria.
Doctors use treponemal tests to confirm results. These look for the antibodies directed towards the bacteria themselves. They also look for antibodies directed towards antigens — the toxic substances the bacteria produce. They search for other treponemes (toxins that induces an immune response from the body) as well.
The use of one type of test alone can be insufficient, and can produce false positive results.
You will first be screened for syphilis and only given further testing to confirm if the initial screening results turn out positive.
These screening tests include:
- Venereal disease research laboratory (VDRL) test – This test looks for a high amount of antibody production to confirm infection.
- Red plasma reagin (RPR) test – This looks for antibodies produced against syphilis. They specifically look for antibodies directed against the cells already damaged by the infection.
- Rapid immunochromatographic test – This test uses a nitrocellulose strip, similar to a pregnancy test. The strip contains a mix of antigens and a selenium colloid (a serum) which reacts to antibodies against syphilis. Just like a pregnancy test, the area with the colloid will show up as a line if there is a reaction between the antigen-selenium mix and the antibodies that the test is looking for.
More detailed tests to confirm syphilis include: