The diagnostic value of the Wassermann reaction, now well recognized, has, as a direct corollary, the importance of the test as a guide to treatment.
In much of the earlier work it was found that the frequency of negative reactions, especially in the latent stage, bore a direct relation to the amount and efficiency of previous treatment. Later statistics have confirmed the early observations, and to-day it is recognized that the value of a negative reaction, from a diagnostic standpoint, is much affected by recent specific medication.
The view one takes of a positive reaction in the latent stage has much to do with his opinion in regard to the reaction as a guide to treatment. Two possibilities exist: A positive reaction may indicate (1) that the patient once had syphilis and his serum still shows evidence of the old infection, and (2) that spirochetes are present
SWIFT HF. THE EFFECT OF TREATMENT ON THE WASSERMANN REACTION. Arch Intern Med (Chic). 1910;VI(6):626–637. doi:10.1001/archinte.1910.00050340012002