Update on syphilis diagnostics.

Abstract

Purpose of review: Syphilis is rising globally, with resultant increases in morbidity and mortality that disproportionately impact underserved populations. Appropriate screening and testing for syphilis with accurate, reliable, affordable, and timely assays is crucial for combating this epidemic. This review provides a brief overview of laboratory methods for syphilis diagnosis, with a focus on recent updates in diagnostics and directions for future research.

Recent findings: Syphilis can be complex and time-consuming to diagnose and stage appropriately. The historic use of darkfield microscopy for diagnosis has been eclipsed by algorithms that include both nontreponemal and treponemal antibody tests for screening and confirmation of active Treponema pallidum infection. Newer diagnostic modalities include nucleic acid amplification assays (NAATs) and point-of-care testing (POCT), which hold promise for increasing identification of active syphilis but have notable limitations. More work is needed to develop accurate, reliable, affordable, and expeditious tests to optimize syphilis diagnosis.

Summary: Algorithms utilizing a combination of serological treponemal and nontreponemal assays remain standard of care for the diagnosis of syphilis, but recently developed NAATs and POCT assays present opportunities to increase syphilis detection. Further research is warranted to improve upon these testing modalities and explore other markers that could aid in syphilis diagnosis.