Syphilis tests tell if a person has this disease. They look for antibodies to the bacterium, or germ, that causes syphilis. Some tests look for the syphilis germ itself.
Syphilis is a sexually transmitted infection. That means it is spread through sexual contact: vaginal, anal, or oral sex.
Testing is done on blood, body fluid, or tissue samples.
If a first screening test shows signs of syphilis, another test is done to confirm a syphilis infection.
Tests used to screen for syphilis include:
Venereal disease research laboratory (VDRL) test. The VDRL test checks blood or spinal fluid for an antibody that can be produced in people who have syphilis. This antibody is not produced as a reaction to syphilis specifically, so the test result could be "abnormal" for reasons other than syphilis.
Rapid plasma reagin (RPR) test. The RPR test also finds syphilis antibodies.
Tests to confirm syphilis
Tests used to confirm a syphilis infection include:
Enzyme immunoassay (EIA) test. This blood test checks for syphilis antibodies. A positive EIA test should be confirmed with either the VDRL or RPR tests.
Fluorescent treponemal antibody absorption (FTA-ABS) test. This test also checks for antibodies. It can be used to find syphilis except during the first 3 to 4 weeks after exposure. The test can be done on a sample of blood or spinal fluid.
Treponema pallidum particle agglutination assay (TPPA). This test also checks for antibodies. It is used after another method tests positive for syphilis. This test is not done on spinal fluid.
Darkfield microscopy. This test uses a special microscope to look for the syphilis germ in a sample of fluid or tissue from an open sore. This test is used mainly to diagnose syphilis in an early stage.
Microhemagglutination assay (MHA-TP). The MHA-TP is used to confirm a syphilis infection after another test shows positive results for syphilis.
Why It Is Done
A syphilis infection can spread through the bloodstream to all parts of the body. If not treated, syphilis can cause severe heart disease, brain damage, spinal cord damage, blindness, and death.