Results of tuberculosis contact tracing: Blackburn 1982-90.

Between 1982 and 1990, 649 index cases of tuberculosis were seen of which 429 (66.1%) were of Indian Subcontinent (ISC) ethnic origin: 7017 close contacts of these cases were screened, 50 cases of tuberculosis were detected (7.7% of notifications) and 372 children given chemoprophylaxis. All cases of tuberculosis detected in the white ethnic group were contacts of smear-positive pulmonary disease, six (46%) found at initial screening, five (38%) at 1 year and one (8%) at 2 year follow-up. Of 37 cases detected in the ISC ethnic group, only 14 (38%) were contacts of smear-positive disease, 17 (46%) being contacts of other respiratory disease, and six (16%) contacts of non-respiratory disease. Eighteen (49%) of ISC cases detected were at initial screening, with six (16%), eight (22%) and three (8%), respectively, at 6 month, 1 year and 2 year follow-up. The results support the revised Joint Tuberculosis Committee advice on contact tracing, with differential contact programmes depending on type of disease and ethnic group of index cases.