Diagnosis of syphilis is made using both non-treponemal and treponemal serologic tests and should not be made on the basis of a single test result. Many laboratories have moved toward using the reverse sequence algorithm as the traditional algorithm can miss late latent disease. In all cases, clinical history and symptoms must also be taken into consideration when diagnosing and staging individuals. The Illinois Department of Public Health provides a comprehensive guide for understanding the syphilis screening algorithms.
FIGURE 3. Algorithms that can be applied to screening for syphilis with serologic tests — CDC laboratory recommendations for syphilis testing in the United States, 2024