OUTBREAK OF PULMONARY TUBERCULOSIS IN WHICH TUBERCULOSIS DEVELOPED FROM QuantiFERON®-TB SECOND GENERATION (QFT-2G) TEST NEGATIVE PERSONS

• Published in: Kekkaku Vol. 82; no. 8; pp. 629 - 634
• Main Authors: YAMAGUCHI, Junichi, OOBA, Yuko, KANEDA, Mie, UCHIDA, Kiyomi, ISHIKAWA, Yo, SUZUKI, Kiminori, YAGI, Takenori, SASAKI, Yuka, YAMAGISHI, Fumio
• Format: Journal Article
• Language: Japanese
• Published: Japan JAPANESE SOCIETY FOR TUBERCULOSIS 01.08.2007
• Subjects: Adult; Chemoprophylaxis; Contacts examination; Disease Outbreaks; False negative; Female; Humans; Interferon-gamma - blood; Male; Mass Screening - methods; QuantiFERO®-TB second generation (QFT2G); Tuberculosis, Pulmonary - diagnosis; Tuberculosis, Pulmonary - transmission
• ISSN: 0022-9776; 1884-2410
• DOI: 10.11400/kekkaku1923.82.629

[Purpose] To clarify the points to be considered when QFT-2G tests are used in the contacts examination by public health center. [Object & Method] We analyzed the results of contacts examination on 43 workplace colleagues (39 y/o and younger)of a pulmonary tuberculosis patient (bII2, Gaffky 9, cough for 1.5 months). [Results] After two months of the last contact with the index case, tuberculin skin tests, QFT-2G tests and chest X-rays were undertaken. After 6 months, chest X-rays were taken, and after 9 months, QFT-2G tests and chest CT scans were also undertaken. The tuberculin skin tests after two months showed a bimodal distribution, and 10 were QFT-2G positive and 2showed doubtful reaction. The latter 12 persons underwent chemoprophylaxis. After 6 months, however, out of 31 QFT2G negative persons, 2 developed pulmonary tuberculosis. Moreover, after 9 months, chest CT scans revealed 5 pulmonary tuberculosis patients. Three out of 7 new patients showed positive or doubtful reactions in QFT-2G tests undertaken after 9 months. [Dis cussion and Conclusion] The sensitivity of QFT-2G tests is reported to be 80 to 90%, and the possibility of false negative is not negligible. We propose measures for public health center to conduct the contacts examination as follows; In case of high QFT-2G positive (including doubtful reaction)rate and/or a bimodal distribution of tuberculin skin test result, many infected persons are likely to be included in the group; and the following measures are recommended; 1) Necessity of chemoprophylaxis should be judged considering both tuberculin skin test results and the situation of contact with the index case, and not only by QFT-2G test results. 2) QFT-2G negative persons also need to be followed with chest X-rays.