Syphilis. Syphilis is a sexually transmitted infection (STI). It is spread by vaginal, oral, or anal sex. A pregnant woman can also spread syphilis to her baby. Syphilis is easy to treat with medicine in the early stages. But without treatment, syphilis progresses to a late stage and can damage your body's organs, leading to severe illness and.

Most laboratories offer serologic detection of syphilis. Unfortunately, the assays and their interpretation are complex and often misunderstood by physicians and patients. Because no one single test definitively diagnoses untreated syphilis, laboratories rely on testing algorithms.