• Tuberculosis and Respiratory Diseases
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• v.82 no.4
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• pp.306-310
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• 2019

Background: Tuberculosis (TB) is increasing in immigrants. We aimed to investigate the current status of latent tuberculosis infection (LTBI) treatment for North Korean Refugees (NKR) compared to South Koreans Contacts (SKC). Methods: TB close contacts in a closed facility of SKC and NKR who underwent LTBI screening in a settlement support center for NKR were analyzed retrospectively. Results: Among tuberculin skin test (TST) ${\geq}10mm$ (n=298) reactors, the males accounted for 72.2% in SKC (n=126) and 19.5% in NKR (n=172) (p<0.01). The mean age was higher in South Korea ($42.8{\pm}9.9years$ vs. $35.4{\pm}10.0years$, p<0.01). Additionally, the mean TST size was significantly bigger in NKR ($17.39{\pm}3.9mm$ vs. $16.57{\pm}4.2mm$, p=0.03). The LTBI treatments were initiated for all screened NKR, and LTBI completion rate was only 68.0%. However, in NKR, LTBI treatment completion rate was significantly increased by shorter 4R regimen (odds ratio [OR], 9.296; 95% confidence interval [CI], 4.159-20.774; p<0.01) and male (OR, 3.447; 95% CI, 1.191-9.974; p=0.02). Conclusion: LTBI treatment compliance must be improved in NKR with a shorter regimen. In addition, a larger study regarding a focus on LTBI with easy access to related data for NKR should be conducted.

• Pediatric Infection and Vaccine
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• v.26 no.1
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• pp.32-41
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• 2019

Purpose: In order to prevent tuberculosis transmission early, it is important to diagnose and treat tuberculosis infection by investigating people who have contact with patients with active tuberculosis. Methods: From July 2014 to June 2017, the intrafamilial childhood contacts of the patients who were diagnosed with active tuberculosis at Chungnam National University Hospital were investigated for the presence of tuberculosis infection. We also retrospectively analyzed the treatment status of children treated with latent tuberculosis infection (LTBI) during the same period. Results: Among the 269 children who had intrafamilial contact with active tuberculosis patient, 20 (7.4%) did not receive any screening. At the first screening, one (0.4%) was diagnosed with pulmonary tuberculosis, seven (2.8%) had a previous history of tuberculosis infection, and 42 patients (16.9%) were diagnosed with LTBI. At the second screening, 29 patients (11.6%) were diagnosed with LTBI, and 61 patients did not finish the investigation. Only 188 (69.9%) out of 269 patients completed the investigation. Ninety patients received treatment for LTBI and 83 patients (92.2%) completed the treatment, of which 18 patients had side effects such as rash, fatigue, and gastrointestinal symptoms. However, there were no serious side effects requiring treatment discontinuation. Conclusions: The completion rate of childhood tuberculosis contact investigation was low, but the completion rate of LTBI treatment was high in children without serious side effects. In order to prevent and manage the spread of tuberculosis, active private-public partnership efforts and education of the patient and guardian are needed.

• Journal of applied mathematics & informatics
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• v.29 no.5_6
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• pp.1097-1115
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• 2011

We consider the global stability of a general tuberculosis model with two differential infectivity, n classes of latent individuals and mass action incidence. This system exhibits the traditional threshold behavior. There is always a globally asymptotically stable equilibrium state. Depending on the value of the basic reproduction ratio $\mathcal{R}_0$, this state can be either endemic ($\mathcal{R}_0$ > 1), or infection-free ($\mathcal{R}_0{\leq}1$). The global stability of this model is derived through the use of Lyapunov stability theory and LaSalle's invariant set theorem. Both the analytical results and numerical simulations suggest that patients should be strongly encouraged to complete their treatment and sputum examination.

• Tuberculosis and Respiratory Diseases
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• v.80 no.1
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• pp.21-26
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• 2017

It is well established that health care workers (HCWs) have a considerably higher risk of occupationally acquired tuberculosis (TB). To reduce the transmission of TB to HCWs and patients, TB infection control programs should be implemented in health care settings. The first and most important level of all protection and control programs is administrative control. Its goals are to prevent HCWs, other staff, and patients from being exposed to TB, and to reduce the transmission of infection by ensuring rapid diagnosis and treatment of affected individuals. Administrative control measures recommended by the United States Centers for Disease Control and Prevention and the World Health Organization include prompt identification of people with TB symptoms, isolation of infectious patients, control of the spread of the pathogen, and minimization of time spent in health care facilities. Another key component of measures undertaken is the baseline and serial screening for latent TB infection in HCWs who are at risk of exposure to TB. Although the interferon-gamma release assay has some advantages over the tuberculin skin test, the former has serious limitations, mostly due to its high conversion rate.

• The Journal of Internal Korean Medicine
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• v.44 no.5
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• pp.1011-1016
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• 2023

We have experienced a case in which herbal medicine was administered to treat drug-induced liver damage and would like to introduce it. A 49-year-old man exhibited a positive result in the interferon-gamma release assay. He had never suffered from tuberculosis in the past, and the route and time of infection could not be confirmed. He had no respiratory or systemic symptoms suggestive of active tuberculosis, and a chest X-ray examination showed no active lung lesions, so he was diagnosed with latent tuberculosis infection. He was confirmed to be within the normal range in the liver function test, renal function test, and complete blood cell count test, and started taking rifampin (600 mg qd). In the screening test performed on the 19th day of taking the drug, other test items were normal, but alanine aminotransferase (ALT) increased to 50 U/L (reference value: 4-40 U/L). In a test performed on the 29th day of taking the drug, ALT was clearly elevated to 102 U/L. Ursodeoxycholic acid and Injinho-tang were taken together with rifampin, and the patient's progress was observed. In a test performed 14 days later, ALT decreased to 26 U/L, within the normal range. It is presumed that Injinho-tang may have partially contributed to alleviating liver damage in this case.

• Pediatric Infection and Vaccine
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• v.23 no.2
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• pp.94-101
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• 2016

Purpose: This study aimed to describe the results of a contact investigation on health care workers after exposure to a house officer with smear-positive pulmonary tuberculosis (TB). Methods: Eighty nine out of 101 subjects who had close contact with the index patient agreed to be enrolled in the investigation. The first contact investigation was conducted approximately 30 days after the index patient's onset of symptoms, followed by the second investigation after 10 weeks. In both, clinical manifestations were studied, and chest X-ray and tuberculin skin test (TST)/QuantiFERON-TB Gold (QFT-G) in dual screening strategy were conducted. Results: The first TST resulted in positive in 34 subjects (38.2%). QFT-G was conducted on 16 subjects who tested positive in the first TST and aged under 36. Six of them (37.5%) were positive. The second TST was conducted on 41 subjects with negative results in the first TST. Seventeen (41.5%) were positive and among them, three (17.6%) showed positive QFT-G. None of the subjects were diagnosed with active TB. The probability of TB infection through contact with the index patient was 7.3% (3/41) in dual screening strategy while it was 41.5% (17/41) in TST strategy. Conclusions: This first hospital-setting contact investigation for tuberculosis in Korea revealed that latent tuberculosis infection (LTBI) rates vary depending on different diagnostic strategies. This indicates the need for systematic guidelines for diagnosing LTBI in health care workers who have professional exposure to TB.

• Journal of Society of Preventive Korean Medicine
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• v.28 no.2
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• pp.55-65
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• 2024

Background : Tuberculosis (TB) remains a significant public health issue worldwide, particularly among healthcare workers (HCWs) at high risk of exposure. Latent tuberculosis infection (LTBI) is a state where individuals are infected with Mycobacterium tuberculosis but do not show clinical symptoms. Early detection and treatment of LTBI are crucial to prevent progression to active TB. This study aimed to investigate the prevalence and risk factors of LTBI among Korean Medicine (KM) workers in Seoul, South Korea. Methods : This study analyzed 368 adults aged 19 and over working in Korean medicine institutions in Seoul by September 2023. Participants underwent a tuberculin skin test (TST) and completed a survey collecting demographic information, occupation, work duration, smoking status, BCG vaccination, TB history, and comorbidities. Data were analyzed using descriptive statistics and chi-square tests, with significance set at p < 0.05. Results : The average age of participants was 43.1 years, with an LTBI prevalence rate of 3.5%. Significant risk factors included age and history of TB, Older age and a history of TB were associated with higher LTBI positivity. Conclusion : The study identified the prevalence and risk factors of LTBI among Korean medicine workers in Seoul. The findings highlight the need for targeted LTBI screening and preventive measures, especially for older workers and those with a history of TB. While the prevalence was lower than in other healthcare settings, the results emphasize the importance of regular LTBI testing and prevention education for KM workers. Future large-scale studies are needed to confirm these findings and further understand the relationship between various risk factors and LTBI in KM settings.

• Tuberculosis and Respiratory Diseases
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• v.68 no.5
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• pp.280-285
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• 2010

Background: $QuantiFERON^{(R)}$-TB Gold In Tube (QFT-G IT) has been used for diagnosing latent tuberculosis infection and active tuberculosis (TB) since 2007. However, there has not been enough data on QFT-G IT for universal use in children. In this study, we evaluated the clinical usefulness of the QFT-G IT in pediatric practice. Methods: We retrospectively reviewed the clinical records of 70 patients younger than 18 years of age who had taken QFT-G IT and had a tuberculin skin test (TST) between July 2007 and July 2009 at Wonju Christian Hospital. The subjects were divided into two groups, asymptomatic TB exposure group and disease group. Four patients who were taking immunosuppressants during the study period were excluded. Results: A total of 66 immunocompetent children were included in this study. Among 27 asymptomatic children who had contact histories of TB, 6 (22.2%) were found to be positive by QFT-G IT. Eleven (40.7%) and 5 (18.5%) children were found to be positive by TST with cutoff values of ${\geq}5mm$ and ${\geq}10mm$, respectively. Agreement was fair to good between QFT-G IT and TST (${\kappa}=0.59$: cutoff value ${\geq}5mm$, ${\kappa}=0.7$: cutoff value ${\geq}10mm$). In disease group, 14 patients (35.9%) were diagnosed with active tuberculosis, 8/14 (57.1%) were positive on TST and 9/14 (64.3%) on QFT-G IT. The positive rate of acid-fast bacilli smear, TB-polymerase chain reaction, and culture for tuberculosis was 11% (1/9), 27.3% (3/11) and 33.3% (3/9), respectively. Conclusion: Our data support that the QFT-G IT can be used as an additional diagnostic tool for latent and active tuberculosis infection in children.

• Biomedical Science Letters
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• v.24 no.2
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• pp.138-142
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• 2018

The incidence of tuberculosis (TB) in the Republic of Korea remains high when compared to the incidence in other Organization for Economic Cooperation and Development (OECD) countries. The prompt diagnosis and effective treatment of latent TB infection (LTBI) are very important in terms of controlling the burden of TB. The tuberculin skin test (TST) has long been the "gold standard" assay for the diagnosis of LTBI. However, it can show false positive results due to Bacille Calmette-$Gu{\acute{e}}rin$ (BCG) vaccination and infection with many environmental nontuberculous mycobacteria (NTM). The interferon gamma release assay (IGRA) using Mycobacterium tuberculosis (MTB)-specific antigens, was developed for the detection of LTBI. The QuantiFERON-TB Gold In-Tube assay is one of the most commonly used forms of the IGRA. In order to compare the diagnostic efficacy of the TST and IGRA in relation to LTBI among BCG-vaccinated healthy donors, whole blood samples were collected from 51 participants, and the results of the TST and IGRA were compared. Of the 51 cases, 18 cases (35.3%) were positive and 33 cases (64.7%) were negative when using the TST, while four cases (7.8%) were positive and 47 cases (92.2%) negative when using the IGRA. There was no correlation between the size of the induration in the TST and the $IFN-{\gamma}$ protein level. In conclusion, the TST showed higher cross-reactivity among the BCG-vaccinated healthy participants, therefore, the IGRA might be the most suitable assay for the rapid screening of LTBI in BCG-vaccinated healthy population, or for TB contact investigation.

• Tuberculosis and Respiratory Diseases
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• v.68 no.6
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• pp.328-333
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• 2010

Background: There are several active tuberculosis (TB) cases in Korean high schools each school year. The risk of transmission in schools is extremely high due to the considerable time spent in closed classrooms. We evaluated the control of latent tuberculosis infection in Korean high schools. Methods: When a student was identified with active TB, tuberculin skin testing was performed on their classmates and on students in their same school grade. When a student had a positive tuberculin skin tests (TST), they underwent follow-up testing with QuantiFERON-TB Gold In-Tube (QFT). The manufacturer recommended a cut-off of 0.35 IU/mL to determine QFT positivity was applied. Results: A total of 131 pulmonary tuberculosis (TB) patients were included based on the criteria for screening TB contacts in the National Tuberculosis Control Program. Seventy-five (57.2%) students tested smear positive. TST were performed on 7,109 students who were classmates of, or in the same grade as, a TB patient. Of the contacts, 1,231 students (17.3%) were TST positive and they were screened with QFT. Six hundred-sixty-six (55.0%) of the tested students returned a positive QFT result and the rate of positivity was significantly associated with the increasing size of TST indurations (p<0.0001). Conclusion: The use of QFT resulted in approximately 45% of TST positive students not being given chemoprophylaxis.