Although tuberculosis is one of the most common of infectious diseases, it is one of the most difficult to diagnose in its early stages. Very many cases progress to spontaneous recovery without ever giving the slightest possibility of diagnosing the process, and only the statistics of post-mortem examinations show how frequently healed and unhealed undiagnosed tuberculous conditions have existed. It is true that by means of the von Pirquet test many cases in which tuberculosis has existed some time during the patient's life can be diagnosed, but the extreme sensitiveness of this test makes it impossible to differentiate cases in the active stages of the disease from those in which the process of the disease was arrested. For this reason the results of the von Pirquet test, though valuable for the exclusion of tuberculosis, are of little value for the diagnosis of the disease, especially in adults.
BRONFENBRENNER J. THE COMPLEMENT-DEVIATION TEST WITH BESREDKA'S TUBERCULIN AND THE OCCURRENCE OF TUBERCULOSIS AMONG SYPHILITICS AS DIAGNOSED BY THIS TEST. Arch Intern Med (Chic). 1914;XIV(6):786-803. doi:10.1001/archinte.1914.00070180019003