Qualitative differences in tuberculin reactivity in patients with tuberculosis, occupational contacts and non-contacts.

Qualitative differences in tuberculin reactivity between patients with pulmonary tuberculosis, occupational contacts and non-contacts were observed. An erythematous reaction at 6-8 hours was frequently observed in both patients and contacts but much less frequently in non-contacts. Itching and the presence of superficial bullae occurred principally in the contact group, and the erythematous reactions at 48 hours were largest in this group. Attention needs to be paid therefore to several characteristics, other than size, of the tuberculin reaction.