[Influence of occupation of the index cases in recent outbreaks of tuberculosis]

PURPOSE, MATERIALS AND METHODS: In order to elucidate risk factors of TB outbreaks, 223 outbreaks reported between 2000 and 2006 in Japan were analyzed according to sex, occupation and outbreaking place of the index case.

In male, the most frequent occupation was permanent workers who infected contacts mainly at workplaces, followed by unemployed people at general hospital or nursing home for the aged. The third was students who infected contacts mostly at school, followed by customer relations workers at companies or amusement places. In female, the most frequent occupation was students who infected contacts at school. Second most frequent was unemployed who infected contacts at general hospitals and nursing homes for the aged, followed by nurses at general hospitals or mental hospitals. Frequent outbreak places were workplaces, schools, general hospitals, amusement places and mental hospitals in male, and general hospitals and schools in female. The risk of becoming the source of TB outbreak was high in teachers/doctors, students, unemployed as well as customer relations workers in male, and teachers/doctors, students as well as nurses in female.

The most important point to prevent outbreaks of TB is to find out TB suspects with relevant symptoms for tuberculosis as early as possible to minimize patient's delay, especially from people with high risk of TB infection to others such as teachers/doctors, students and medical nurses. As most frequent job and place were general permanent workers at workplaces, TB control activities to minimize patient's delay at general workplace is also important.