In a routine PPD skin test among 1st grade pupils in 4 elementary schools, Fukushimaprefecture in April 1989, the number of pupils that showed strongly positive was unusuallyhigh. Moreover, 2 tuberculosis cases were detected among them. Since those childrengraduated the same kindergarten, and one of 6 kindergarten teachers had been complainingcough and hoarseness for about 3 to 5 months before being diagnosed as a smear positivepatient in the contact survey, she was suspected to be the source of infection. Meanwhile, she had been treated for common cold and chronic bronchitis in several clinics, therefore, the main cause of this epidemic was due to the doctor's delay in detecting the case.
With the discovery of 2 additional cases in the contact survey of the kindergarten, therewere 5 cases altogether including the index cases. Three of 4 children's cases had beenvaccinated with BCG. If the children who showed strong reaction to tuberculin andeventually treated prophylactically with isoniazid were asumed the infected, the rate ofdevelopment of disease among the infected was 13.6 to 27.3%. Usually, lymphnodeenlargement of the hilum is said not to be observed among vaccinated, though slightly, itwas evident among the cases in this epidemic.
