A 36-year-old man, an unemployed waiter, a regular patron of two bars living in a Czech city suffered for about a year from disorders caused probably by tuberculosis (TB). When hospitalised, diabetes mellitus and extensive lung TB were diagnosed. TB was found also at the post mortem examination when the patient died one week later. Screening of his contacts by tuberculin s kin tests (2TU RT 23 W.Tw.80) provided data for analyzing the usefulness of tuberculin tests for monitoring of propagation of TB infection among BC G vaccinated population with high TB prevalence in the past. A statistically significant difference was found in tuberculin reactivity between 543 contacts and 232 individuals who had not reported contact with the patient. A skin reaction of 12 mm and more was found in 55.6 % contacts while only in 2.6 % of those included in the second group. The high tuberculin reactivity was proved in the individuals exposed to massive TB infe ction. Neither BCG vaccination, nor possible previous contact with TB in the past seemed to influence the actual tuberculin reactivity in the group of non-contacts. Furthermore, it is indicative of the fact that unknown TB sources are rare among the Czech population. The high tuberculin reactivity is suggestive of a fresh infection and justifies the tuberculin testing and the application of chemoprophylaxis.

        Key words: contact with tuberculosis, tuberculous infection, tuberculin test, BCG vaccinated population