Syphilis survey reveals need for accurate testing for early infection

Although syphilis is one of the oldest known diseases, most health professionals do not have access to the tests necessary to reliably diagnose it in its earliest and most infectious stage. A recent survey of infectious diseases specialists regarding the diagnosis and treatment of syphilis appears in the November 15, 2009 issue of Clinical Infectious Diseases, now available online. Definitive diagnosis of primary syphilis (the earliest stage of syphilis infection) relies on direct fluorescent antibody testing or darkfield microscopy, both of which are often unavailable in a clinical setting. Blood tests are commonly used to diagnose syphilis; however those tests produce false negatives in 20-30 percent of primary syphilis cases, allowing for the possibility of ongoing transmission.

According to study author Deborah Dowell, MD, of the Centers for Disease Control and Prevention (CDC), "Eighty-one percent of our survey respondents did not have access to darkfield microscopy. These clinicians should treat presumptively if they suspect early syphilis in their patients." Dr. Dowell also notes that there is a clinical and public health need for a rapid point of care test to reliably diagnose primary syphilis.

The survey also shows that most respondents treat HIV-positive patients who have secondary syphilis with three weekly penicillin injections although there is no evidence of improved outcomes for treating with more than one injection. Physicians with more syphilis management experience were more likely to treat with the recommended one injection, which suggests that physicians with less experience managing syphilis may lack confidence that management according to established guidelines is sufficient to prevent adverse outcomes.

Source: Infectious Diseases Society of America