Syphilis is a sexually transmitted disease, which spreads easily during sexual contact.
Treponema pallidum is a species that causes syphilis in humans.
It is an infectious disease. It is mainly seen in adults between 20-29 years of age who are sexually active.
There are three stages of syphilis, primary syphilis, secondary syphilis, and tertiary syphilis.
During the primary stage, primary sores or chancres will be formed in 2-3 weeks after getting infected, but no symptoms will be seen. These sores will disappear in 4-5 weeks.
If the primary syphilis is not treated properly, secondary syphilis occurs in about 2-8 weeks after primary syphilis. The tertiary syphilis is the final stage and it will spread to the brain, heart, skin, bones, and nervous system.
Blood tests to detect the syphilis bacteria:
Blood tests will be done to detect the bacteria that cause syphilis and to diagnose this disease. Tests that are used to screen this disease are venereal disease research laboratory (VDRL) test, rapid plasma reagin (RPR) test, enzyme immunoassay (EIA) test, and many more.
VDRL is one of the screening tests for syphilis that checks the antibodies produced by Treponema pallidum. This VDRL test is performed on a sample drawn from blood or spinal fluid (if the patient is suspected to have syphilis involving the brain, the VDRL will be performed on the spinal fluid).
If the results are negative, it means no antibodies of syphilis are detected. Most likely, the screening test will be positive in the secondary and latent syphilis. During primary and tertiary syphilis, this screening test will be false negative.
So, VDRL test is not useful in the early or advanced stages of syphilis.
RPR (rapid plasma reagin) test is similar to the VDRL test, which is a screening test for syphilis. RPR test looks for antibodies present in the blood of the patients, who has this disease.
As the body does not always produce antibodies in response to Treponema pallidum bacteria, this test will not be always accurate. More screening tests may be needed in order to rule out syphilis.
EIA (enzyme immunoassay) test is a newer blood test that also screens for the antibodies of syphilis. If the results are positive, it will be confirmed either by VDRL or RPR tests.
Many more new screening tests are available to detect the syphilis, which include line immunoassay, enzyme-linked immunosorbent assay, rapid syphilis test, immunochromatic strip, RPR card, etc.
If the screening test confirms the syphilis by either of the above tests, the next step would be to confirm the diagnosis of syphilis with more specific tests. The tests that are used to diagnose the syphilis include:
- Fluorescent treponemal antibody absorption (FTA-ABS) test.
- Treponema pallidum particle agglutination assay (TPPA) test.
- Darkfield microscopy.
- Microhemagglutination assay (MHA-TP) test.
These tests help in detecting the antibodies of the syphilis bacteria for syphilis treatment.
In addition to screening the patients with signs and symptoms of syphilis, a sexually transmitted disease, screening of syphilis will be done as a part of prenatal care during pregnancy. Also, several states require screening for syphilis before getting married.