[Early detection of tuberculosis by the evaluation of contacts]

We have evaluated the close contacts of 191 patients diagnosed of tuberculosis in our center between 1984 and 1987. The overall number of evaluated contacts was 666, and the mean number of contacts for each index case was 3.7. In 55% of the evaluated population PPD reaction was positive, and their mean age was 33.3 years. In 132 cases chemoprophylaxis was given during one year (22%). Forty-one new cases of tuberculosis were detected, with a mean age of 25.6 years. In ten new cases the source of infection was familial. When the contacts were distributed according to the bacteriologic status of the index case (direct investigation of tubercle bacilli positive in 103 cases and negative in 167), the rate of disease and infection was significantly higher among those related to positive patients. In the group related to negative patients we discovered 7 new cases of active tuberculosis. Our results confirm the usefulness of the systematic evaluation of the contacts of tuberculous patients in our area, as it permits the identification of an important number of new patients which should be adequately treated. This practice contributes to interrupt the epidemiologic transmission chain of the disease and to facilitate its eradication.