The Infectivity of Pulmonary Tuberculosis in Korean Army Units: Evidence from Outbreak Investigations / 결핵및호흡기질환

BACKGROUND@#Tuberculosis (TB) causes substantial health burden to the Korean military. This study aims to assess the impact of infectious TB cases on close and casual contacts in the Korean Army settings based on contact investigation data.@*METHODS@#Six Army units with infectious TB cases from September 2012 to May 2013 were enrolled in the study. We analyzed the clinical data from close and casual contacts screened using the tuberculin skin test (TST) and QuantiFERON-TB Gold In-Tube to identify latent tuberculosis infection (LTBI) cases. For the control group, 286 military conscripts with no reported TB exposure were tested by TST only.@*RESULTS@#Of the 667 contacts of index cases, LTBI cases identified were as follows: 21.8% of close contacts of smear-positive cases (71/326), 8.5% of casual contacts of smear-positive cases (26/305), and 2.8% of close contacts of smear-negative cases (1/36). In the control group, 16.8% showed positivity in TST. In a multivariate analysis, having stayed in the same room or next room with TB patients was identified as a risk factor of LTBI.@*CONCLUSION@#Using the data from TB contact investigations in the Korean Army units, we found an overall LTBI rate of 14.7% among the contacts screened. This study demonstrates that contacts living in the same building, especially the same room or next room, with TB patients are at a high risk of acquiring LTBI, serving as additional evidence for defining close and casual contacts of a TB patient with regard to Army barrack settings.

The Infectivity of Pulmonary Tuberculosis in Korean Army Units: Evidence from Outbreak Investigations / 결핵

BACKGROUND: Tuberculosis (TB) causes substantial health burden to the Korean military. This study aims to assess the impact of infectious TB cases on close and casual contacts in the Korean Army settings based on contact investigation data. METHODS: Six Army units with infectious TB cases from September 2012 to May 2013 were enrolled in the study. We analyzed the clinical data from close and casual contacts screened using the tuberculin skin test (TST) and QuantiFERON-TB Gold In-Tube to identify latent tuberculosis infection (LTBI) cases. For the control group, 286 military conscripts with no reported TB exposure were tested by TST only. RESULTS: Of the 667 contacts of index cases, LTBI cases identified were as follows: 21.8% of close contacts of smear-positive cases (71/326), 8.5% of casual contacts of smear-positive cases (26/305), and 2.8% of close contacts of smear-negative cases (1/36). In the control group, 16.8% showed positivity in TST. In a multivariate analysis, having stayed in the same room or next room with TB patients was identified as a risk factor of LTBI. CONCLUSION: Using the data from TB contact investigations in the Korean Army units, we found an overall LTBI rate of 14.7% among the contacts screened. This study demonstrates that contacts living in the same building, especially the same room or next room, with TB patients are at a high risk of acquiring LTBI, serving as additional evidence for defining close and casual contacts of a TB patient with regard to Army barrack settings.

Occupational Risk of Latent Tuberculosis Infection in Health Workers of 14 Military Hospitals

Tuberculosis (TB) is a known occupational risk to health workers. Identifying risk factors in health care settings is critical to the prevention of TB for health workers and patients. In 2014, we carried out a TB screening and survey for 902 health workers from 14 selected military hospitals to determine the prevalence rate of latent tuberculosis infection (LTBI) as well as occupational risk factors. Of all subjects, 19.5% reported having provided TB patient care for 1 year or more (176/902), and 26.9% (243/902) were positive for the tuberculin skin test (TST) (10 mm or more of induration). Additionally, 21.4% (52/243) of those who tested positive were also positive for the interferon-gamma release assay (IGRA). The proportion of LTBI in the study population was 5.8% (52/902). In a multivariate logistic regression analysis, providing TB patient care for one year or more was the only significant occupational risk factor (adjusted odds ratio [aOR], 2.27; 95% confidence interval [CI], 1.13–4.56). This study suggests that military health workers working with TB patients should be regularly examined by chest radiography, TST and IGRA to detect LTBI in the early stage and control nosocomial infection of TB.

The diagnostic accuracy of notified new culture-negative pulmonary tuberculosis patients in public healthcare centers / 대한내과학회지

BACKGROUND/AIMS: The notification rate based on the Korean tuberculosis (TB) surveillance system has been widely used to evaluate the TB burden in Korea. However, few studies have examined the accuracy of TB diagnosis among notified cases. This study evaluated the diagnostic accuracy of microbiologically not proven cases notified as 'new pulmonary TB patients' at public healthcare centers. METHODS: We reviewed the clinical symptoms and initial and follow-up chest radiographs of notified smear-and-culture- negative TB cases in randomly selected healthcare centers between Jan 2005 and Dec 2005. Patients who had symptoms, initial chest radiographs compatible with pulmonary TB, and radiological improvements after treatment were diagnosed as 'probable TB', while patients who did not meet these three criteria were diagnosed as 'probably not TB'. RESULTS: The analysis included 263 patients. The median age of the notified TB cases was 41 years, 60.8% of them were male, and 43.2% were 'probable TB' patients. Overall, 82.0% of the patients had either initial chest radiographs compatible with pulmonary TB or radiological improvements after treatment. Ultimately, 4.9% were 'probably not TB' patients. CONCLUSIONS: Most of the new notified pulmonary TB patients not confirmed microbiologically in public clinics can be considered real TB patients, although there are some over diagnosed cases.

Boosted Reaction on Two-Step Tuberculin Skin Test among Military Personnel in South Korea, a Setting with an Intermediate Burden of Tuberculosis and Routine Bacille Calmette-Guerin Vaccination

This study was performed to estimate the rate of boosted reaction in the two-step tuberculin skin test (TST) and to evaluate the associated factors among military personnel of South Korea, which has an intermediate burden of tuberculosis (TB) and a routine bacille Calmette-Guerin (BCG) vaccination policy. Two-step TST was performed on 264 military personnel who did not have a history of close contact to TB. Subjects with a negative reaction to the first test of or =10 mm) on the initial TST was observed in 126 (48%) of the subjects. A boosted reaction on the second TST developed in 32 (23%) of the 124 subjects with a negative initial TST. In multiple logistic regression analysis, the size of the initial TST reaction was the only factor associated with a boosted reaction on the second TST. The high rate of boosted reaction among healthy adults in South Korea suggests that two-step TST should be performed to assess the baseline TST reactivity in settings with an intermediate burden of TB and routine BCG vaccination policy, especially among subjects with an initial TST reaction that is > or =5 mm.

Tuberculosis among Dislocated North Koreans Entering Republic of Korea since 1999

The collapse of North Korea's public health system has increased the development of tuberculosis (TB) in its populace. This study investigated the prevalence of active and latent TB infection (LTBI) in such people who have settled in the Republic of Korea since 1999. From 1999 to August 2006, 7,722 dislocated North Koreans entered the Republic of Korea and all were screened immediately for active TB. Demographic and clinical characteristics were reviewed from the official records of the Settlement Support Office for Dislocated North Koreans, based in the Ministry of Unification. Of 7,722 participants, 87 (1.13%) were diagnosed with active TB from 1999 to August 2006. Of these, 78 (90%) had pulmonary TB. Checking for the presence of a Bacille Calmette-Guerin (BCG) scar and tuberculin skin test has been performed in all dislocated North Koreans since November 2005. Of 1,112 participants, BCG vaccination scars were found in 67.4%. The tuberculin-positive rate using two tuberculin unit doses of the purified protein derivative RT23 (> or =10 mm in diameter) was 81.5%. The prevalence of active TB and LTBI in dislocated North Koreans was high. Because this group bears a disproportionate burden of TB, we need to initiate a specific control programme and to plan for the impact of this disease in the Republic of Korea.