Serologic tests for syphilis.

Not since the early 1950s has the number of new cases of syphilis been as high as it is now. The infectious agent, Treponema pallidum, is extremely difficult to culture in vitro and almost impossible to see by conventional light microscopy. A nonspecific antibody test is used for screening and a specific treponemal antibody test for confirmation. Because of the complexity of the disease, the sensitivity and specificity of a given test can vary according to disease stage. The physician must understand the limits imposed on testing by the disease process and the special circumstances that prevail in testing patients for prenatal and congenital syphilis as well as neurosyphilis. With early detection and treatment, cure can be achieved and long-term complications avoided.