The role of chest CT scanning in TB outbreak investigation.
BACKGROUND
In TB outbreaks, detecting active cases is the key step in stopping transmission of the disease. The aim of this study was to evaluate the role of high-resolution CT (HRCT) scanning of the chest in the investigation of a TB outbreak that developed in a cohort of 92 soldiers in the South Korean army.


METHODS
Outbreak investigation, including tuberculin skin test (TST), QuantiFERON TB Gold In-Tube (QFT) test, and simple chest radiograph (CXR), was performed. For participants with any abnormal findings in these tests, HRCT scanning was done. Active pulmonary TB was diagnosed based on sputum studies or HRCT scan findings. In addition, participants with positive results in both TST and QFT were treated as having a latent TB infection (LTBI). TST and QFT were repeated in participants with a positive result in one of these tests. CXR was repeated in all participants at 3 and 6 months of follow-up.


RESULTS
Eighty-seven participants completed the study protocol. Among them, 18 active TB cases were diagnosed. Nine of these had normal CXR, but had lesions that were suggestive of active TB on HRCT scan. Twenty-two participants with normal HRCT scans and positive results with TST and QFT at initial investigation were treated as LTBI. Among 13 participants with normal CXR and positive results in either TST or QFT, nine completed a 3-month investigation. All but one of nine participants revealed positive results in both tests.


CONCLUSIONS
Inclusion of HRCT scanning in the outbreak investigation of TB may be helpful in differentiating active TB from LTBI more reliably.


BACKGROUND
clinicaltrials.gov; Identifier: NCT00889759.
Lee
Sei Won
SW
Division of Pulmonary and Critical Care Medicine, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Irwon-dong, Gangnam-gu, Seoul, 135-710, Republic of Korea.
Jang
Yoon Soo
YS
Park
Chang Min
CM
Kang
Hee Yoon
HY
Koh
Won-Jung
WJ
Yim
Jae-Joon
JJ
Jeon
Kyeongman
K
D000328:Adult; D003937:Diagnosis, Differential; D004196:Disease Outbreaks; D005500:Follow-Up Studies; D006801:Humans; D007371:Interferon-gamma / Q000097:blood; D055985:Latent Tuberculosis / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D008297:Male; D008889:Military Personnel; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification; D013902:Radiography, Thoracic; D056910:Republic of Korea / Q000453:epidemiology; D013183:Sputum / Q000382:microbiology; D014057:Tomography, X-Ray Computed / Q000639:trends*; D014374:Tuberculin Test; D014376:Tuberculosis / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000453:epidemiology*
D007371:Interferon-gamma