[Outbreak of pulmonary tuberculosis in which tuberculosis developed from QuantiFERON-TB second generation (QFT-2G) test negative persons].
OBJECTIVE
To clarify the points to be considered when QFT-2G tests are used in the contacts examination by public health center.


OBJECTIVE
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 2 showed doubtful reaction. The latter 12 persons underwent chemoprophylaxis. After 6 months, however, out of 31 QFT-2G 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.


CONCLUSIONS
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.
Yamaguchi
Junichi
J
Department of Health Promotion, Public Health Office of Chiba City, 1-3-9, Saiwai-cho, Mihama-ku, Chiba-shi, Chiba 261-8755, Japan. junichi-yamaguchi@city.chiba.jp
Ooba
Yuko
Y
Kaneda
Mie
M
Uchida
Kiyomi
K
Ishikawa
Yo
Y
Suzuki
Kiminori
K
Yagi
Takenori
T
Sasaki
Yuka
Y
Yamagishi
Fumio
F
D000328:Adult; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000097:blood*; D008297:Male; D008403:Mass Screening / Q000379:methods*; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000635:transmission
D007371:Interferon-gamma