The Significance of the Time Element in Tuberculous Infiltrations

¹ Tuberculosis Control Unit, Division of Public Institutions, State of Minnesota, Saint Paul, Minnesota.

The establishment of the original tuberculosis infiltration following the primary infection has been discussed from the clinical and epidemiological point of view. The evaluation of old lesions relative to later changes in the infiltration has been reviewed in a group of cases that have been observed over a period of time from one to four years. The time during which the pattern of infiltration becomes set is discussed in relation to the current tendency to confine case finding programs to x-ray surveys on an interval of one to five years.

The large group of individuals showing shadows, usually apical, has been discussed in relationship to the total tuberculosis load requiring continued follow-up supervision. These cases, apparently minimal at the peak of development, have remained consistently negative for the period observed having had at least one series of one to four gastric lavage examinations per year. We do not find our positive cases or our reactivations among this group of patients, in fact, a very considerable number of active cases are not found to be associated with any older evidence of a tuberculosis infection other than a positive tuberculin test. The time element involved between the positive reactors and the onset of symptoms leading to progressive tuberculosis has not yet been determined. A positive tuberculin reaction is the first requirement in the development of clinical disease. There has been no apparent relationship between the recently developing tuberculin positive case and early breakdown with tuberculosis. The inactive cases shown by apical shadows at the present time represent over seventy-five per cent of the total number found on x-ray among our mentally ill. It would seem that this group which does not require therapy or isolation for control purposes must remain Of historical interest only.