[Outbreak of tuberculosis among middle aged employees in an office]

We experienced an outbreak of tuberculosis in a salesmen's office during the period from 1993 to 1997. The outbreak was detected retrospectively. In July, 1997, a 47-year-old man was diagnosed as pulmonary tuberculosis. As he worked with a 42-year-old man who was already registered in our health center, we suspected an outbreak and started a survey. Contact examinations were carried out for 9 employees of his office and 3 members of his friends. As the result of these examinations, one employee showed strongly positive tuberculin skin test, and was indicated isoniazid chemoprophylaxis. Furthermore, some contacts told us that seven cases of active tuberculosis and three cases of primary infection indicated chemoprophylaxis had occurred among employees and their family members. The index case was a 41-year-old man who was diagnosed as tuberculosis in January, 1993. The second case among employees had previous history of pulmonary tuberculosis. Almost the patients among the employees had a hard life suffering from debts, and had heavy alcohol use. These facts may partly explain the spread of tuberculosis in this office. As each case was registered at different health centers, we hadn't noticed the outbreak for 4 years. But it is true that insufficient approach of health centers to contacts caused a serious delay of detecting the outbreak. A thorough investigation for contacts and complete contact examinations are needed.