Investigations into the significance of routine health examinations for tuberculosis in teachers based on the analysis of results of extraordinary health examinations

Abstract

School teachers are regarded as one of the danger groups in contracting tuberculosis infection and are subjected to strict tuberculosis controls, since when they develop tuberculosis, many school children are exposed to infection to the disease. However, the recent decrease in the incidence of tuberculosis in Japan has led to disputes concerning the significance of routine mass health examinations for tuberculosis. In this study, the significance of routine health examinations for tuberculosis in teachers was investigated by the analysis of the results of extraordinary health examinations carried out for tuberculosis in teachers as the index cases. A total of 496 extraordinary health examinations were carried out by Nagoya City from 1975 to 1986 and by Aichi Prefecture from 1980 to 1995. In 49 instances of these examinations, teachers were regarded as index cases, which included 25 teachers of public primary, middle or high schools and 14 teachers of private schools, including private instructors for piano, painting or calligraphy, and teachers for supplementary education. The results of these examinations in both groups were compared, regarding the routes of notification, the disease status of the index cases, and the frequency and the scale of the infections of tuberculosis observed among contacts with the index cases. "Group infections of tuberculosis" was defined as instances the infection in which 20 or more cases were infected by the index case, "small scale group infection" as 5-19 infected cases, and "cases with infection" as 1-4 infected cases. The result obtained were as follows. 1. The response rates to routine health examinations were 99.9% in the teachers of public primary, middle or high schools, and about 20-30% in the teachers of private schools. 2. The proportion of the cases notefied by routine examinations were 68.0% in the former group and 21.4% in the latter group. The cases notefied before the onset of the symptoms in the former group was significantly more frequent than in the latter group. 3. In the former group, no far advanced cases were identified, whereas 2 (14.3%) far advanced cases were identified in the latter group. The cases with amount of tubercle bacilli in sputum exceed 3 on the Gaffky scale were 32.0% in the former group and 61.5% in the latter group. 4. One (4.0%) case of the "group infections of tuberculosis" was observed in the former group, and 2 (14.3%) cases in the latter group. "Small scale group infection" was observed in 4.0% of the former group and in 21.4% of the latter group, and "cases with infection" in 8.0% of the former group and in 35.7% of the latter group. The frequency and the scale of the infections of tuberculosis observed among contacts with the index cases was significantly smaller in the former group than in the latter group. In conclusion, routine health examinations for tuberculosis for teachers seems valuable for the early diagnosis of tuberculosis cases and for the prevension of the infection of tuberculosis in schools.