title: [Detection of tuberculosis infection using a whole blood interferon gamma assay in a contact investigation--evaluation using quantiFERon TB-2G].
abstract: OBJECTIVE
  The purpose of this study was to evaluate the usefulness of a novel method of detecting tuberculosis infection, QuantiFERON TB-2G (QFT), in a large scale contact investigation when an outbreak of mass tuberculosis infection was suspected.
  
  
  METHODS
  The index case was a health-care worker who worked in a maternity hospital. The investigated contacts were categorized as follow according to the grade of closeness of contact; the "very close" contact group (11 subjects), the "close" contact group (33 subjects), and the "non-close" contact group (3,791 subjects). For the former two groups, tuberculin skin test (TST), chest X-ray examination and QFT were conducted. For the last contact group, TST and chest X-ray examination were conducted only to subjects who aged less than 29 years old, while only chest X-ray examination was conducted to those aged 30 years or older. The QFT test, i.e., a whole blood interferon-gamma assay using Mycobacterium tuberculosis-specific antigens, was performed to the "very close" and "close" contacts, and for strong tuberculin reactors among the "non-close" contacts.
  
  
  RESULTS
  The number of infected subjects in the "very close" contact group, the "close" contact group, and the "non-close" contact group were 7, 7, and 277, respectively, based on TST results. On the other hand, the number of infected subjects in each group were 3, 2, and 5, respectively, based on the QFT test.
  
  
  CONCLUSIONS
  If the indication of chemoprophylaxis was determined based on TST test, this case would have been regarded a large tuberculosis outbreak. However, the use of the QFT test greatly reduced the number of the infected persons, so that the possibility of such massive TB outbreak was denied. Thus, the use of QFT, with which TB infection could be detected more accurately, seems to be very beneficial in contact investigations.
authors.affiliation: Fukui Public Health Center, 2-8-8, Nishikida, Fukui-shi, Fukui 918-8540 Japan. h-miyashita-sd@pref.fukui.lg.jp
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Miyashita
authors.forename: Kazue
authors.initials: K
authors.lastname: Higuchi
authors.forename: Noriko
authors.initials: N
authors.lastname: Higashiyama
authors.forename: Satoko
authors.initials: S
authors.lastname: Oki
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Harada
authors.forename: Yukie
authors.initials: Y
authors.lastname: Sekiya
authors.forename: Shinji
authors.initials: S
authors.lastname: Shishido
authors.forename: Toru
authors.initials: T
authors.lastname: Mori
mesh_terms: D000328:Adult; D000942:Antigens, Bacterial / Q000276:immunology*; D016358:Contact Tracing; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000097:blood*; D008297:Male; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D014374:Tuberculin Test; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis*
chemical_list: D000942:Antigens, Bacterial; D007371:Interferon-gamma