What is the diagnostic test commonly used for syphilis?

The VDRL (Venereal Disease Research Laboratory) and RPR (Rapid Plasma Reagin) tests are the primary screening tools used to diagnose syphilis. These tests detect non-treponemal antibodies that are produced in response to the syphilis-causing bacterium, Treponema pallidum. They are commonly used due to their ability to quickly indicate the presence of syphilis, often before more specific tests are conducted.

While the ELISA test can also detect syphilis by identifying treponemal antibodies, it is generally used as a confirmatory test rather than as a primary screening tool. Culturing the bacteria is not typically performed for syphilis due to the difficulty of growing Treponema pallidum in vitro. Additionally, a CT scan is not relevant to the diagnosis of syphilis, as it is primarily used for imaging purposes and does not provide information about infectious diseases. Thus, the VDRL/RPR tests are essential for the rapid and effective diagnosis of syphilis.