A tuberculosis contact investigation involving a large number of contacts tested with interferon-gamma release assay at a nursing school: Kanagawa, Japan, 2012
DOI:
https://doi.org/10.5365/wpsar.2018.9.1.001Abstract
Objectives: In May 2012, a teacher of a nursing school with nearly 300 staff members and students in Japan was diagnosed with sputum smear-positive pulmonary tuberculosis (TB), leading to a large contact investigation involving nearly 300 contacts. Herein we describe the contacts’ closeness to the index TB patient and the positivity of interferon-gamma release assay (IGRA).
Methods: TB was diagnosed when a person had samples that tested bacteriologically positive for TB, or was determined to have TB by a physician. A latent TB infection (LTBI) case was defined as one in which a person tested positive in IGRA.
Results: A total of 288 persons were screened with IGRA; however, two were excluded because of histories of TB and LTBI treatment; thus 286 were analyzed. Eleven persons (3.8%, 95% confidence interval [95%CI]: 1.9-6.8) tested positive for IGRA. Of the 11, a third year student was found to have pulmonary TB disease by chest X-ray. The positivity in IGRA among close contact staff members (4 of 21, 19%, 95%CI: 5.4-42%) with a statistically significant relative risk of 17 (95%CI: 2.0-140) was high compared with that of the third year students (1 of 88, 1.1% [95%CI: 0.028-6.2]). The Cochran-Armitage test revealed a statistically significant trend in the risk of TB infection among the staff and students (close contact staff> 2nd year> 1st year> 3rd year students, p<0.0025).
Discussion: The authors thus recommend that teachers should undergo health examinations, including regular chest X-ray examinations.
References
Katsuda N, Hirosawa T, Reyer JA, Hamajima N. Roles of public health centers (Hokenjo) in tuberculosis control in Japan. Nagoya J Med Sci. 2015;77(1-2):19-28.PMID: 25797967
Ota M, Kato S. Risk of tuberculosis among air passengers estimated by interferon gamma release assay: survey of contact investigations, Japan, 2012 to 2015. Euro Surveill. 2017;22(12):30492 10.2807/1560-7917.ES.2017.22.12.30492
Centers for Disease Control and Prevention Guidelines for the investigation of contacts of persons with infectious tuberculosis; recommendations from the National Tuberculosis Controllers Association and CDC, and Guidelines for using the QuantiFERON-TB Gold test for detecting Mycobacterium tuberculosis infection, United States. MMWR Recomm Rep. 2005;54:1-37.
Higuchi K, Sekiya Y, Igari H, Watanabe A, Harada N. Comparison of specificities between two interferon-gamma release assays in Japan. Int J Tuberc Lung Dis. 2012;16(9):1190-2. 10.5588/ijtld.11.0829
Diel R, Loddenkemper R, Nienhaus A. Evidence-based comparison of commercial interferon-gamma release assays for detecting active TB: a metaanalysis. Chest. 2010;137(4):952-68. 10.1378/chest.09-2350
Sester M, Sotgiu G, Lange C, Giehl C, Girardi E, Migliori GB, et al. Interferon-γ release assays for the diagnosis of active tuberculosis: a systematic review and meta-analysis. Eur Respir J. 2011;37(1):100-11. 10.1183/09031936.00114810
Ogiwara T, Kimura T, Tokue Y, Watanabe R, Nara M, Obuchi T, et al. Tuberculosis screening using a T-cell interferon-γ release assay in Japanese medical students and non-Japanese international students. Tohoku J Exp Med. 2013;230(2):87-91. 10.1620/tjem.230.87
Fujikawa A, Fujii T, Mimura S, Takahashi R, Sakai M, Suzuki S, et al. Tuberculosis contact investigation using interferon-gamma release assay with chest x-ray and computed tomography. PLoS One. 2014;9(1):e85612. 10.1371/journal.pone.0085612
Tuberculosis Surveillance Centre, Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association. Patient classification 2015 In: Tuberculosis in Japan Annual Report - 2016. (available at: http://www.jata.or.jp/rit/ekigaku/index.php/download_file/-/view/3804/) Accessed on 31 May 2017.
School Safety and Health Act, (In Japanese. available at http://law.e-gov.go.jp/htmldata/S33/S33HO056.html) Accessed on 26 May 2017.