[Minor outbreak of Tuberculosis infection in a junior high school--infection from a preventable case]

A second-year junior high school student (14 years old) was diagnosed as pulmonary tuberculosis. She was a member of the volleyball club in the school. She complained a high fever of 39 degrees at first on September 13, 2001. She visited a local physician and was administered medicine for a cold. On September 18, she was seen again for cough and fever, and informed the physician that her father was under treatment for pulmonary tuberculosis since June 2000. As a result, she was examined by chest X-ray, and was diagnosed as pulmonary tuberculosis with moderately positive smear and she was referred to hospital "N" where she was admitted on the next day. Three days after admission, a smear specimen of her sputum was heavily positive for tuberculosis bacilli. She had not been given any preventive chemotherapy when her father was diagnosed with TB because the results of her tuberculin skin test performed two months after her father's onset did not meet the criteria for preventive chemotherapy. Restriction fragment length polymorphism (RFLP) was carried out with 2 strains of tuberculosis bacillus isolated from her and her father, and the RFLP pattern of both strains was same. Thus, it can be concluded that the patient was infected from her father and developed pulmonary tuberculosis. A contact survey was subsequently carried out on October 4, 2001 for 107 students and 20 teachers at the school. None of the subjects examined showed any abnormalities on their chest X-ray. A tuberculin skin test survey of 105 students and one teacher was also carried out on November 12, 2001, about 2 months after the final contact. The diameter of skin reactions revealed a monomodal distribution pattern in subjects. The results of the present tuberculin skin test were verified with respect to the degree of contact and last tuberculin test in routine health examination at the school. Four students who had close contact with the patient evidently and showed a strong positive skin reaction of more than 30 mm in diameter in the present tuberculin skin test, accompanied by enhanced reaction of more than 20 mm compared with the last tuberculin skin test, were administered preventive chemotherapy.