Are There Paradoxic Serologic Reactions in Syphilis?

The serology of syphilis during late years has reached a high degree of perfection. The number of syphilitic persons being detected by means of tests of the blood and spinal fluid is larger today than ever before. Yet, there are instances in which one may encounter frank syphilis and a negative serologic reaction. Indeed, a test which is sensitive enough to detect latent syphilis without symptoms may give a negative reaction in the face of a definite clinical picture of syphilis. Then, again, there are the fluctuating serologic reactions following therapy, so annoying to the clinician. A serologic test at a given time after therapy might give negative results, leading the clinician to believe that the therapy is having definite effect on the serologic picture, but a subsequent examination might reveal a positive reaction. On the other hand, the reaction may be positive some time after therapy and become negative