What are the tests for syphilis?

Syphilis blood test

Blood tests for syphilis are the main method of diagnosis for syphilis. There are two groups of tests:

• treponemal (specific)
• non-treponemal (non-specific)

Enzyme immunoassay (EIA) tests

In recent years, enzyme immunoassay (EIA) tests have become established as the screening test of choice in syphilis. A positive screening test with both positive specific and non-specific treponemal tests on the initial sample is needed to demonstrate infection.

EIA for IgM is useful if primary syphilis is suspected. IgM is detectable towards the end of the second week of infection while IgG is detectable usually in the fourth or fifth week. All tests are usually positive in secondary syphilis.