• Korean Journal of Clinical Laboratory Science
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• v.42 no.1
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• pp.1-15
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• 2010

Swine influenza virus (SIV) or swine-origin influenza virus (S-OIV) is endemic in swine, and classified into influenza A and influenza C but not influenza B. Swine influenza A includes H1N1, H1N2, H3N1, H3N2 and H2N3 subtypes. Infection of SIV occurs in only swine and that of S-OIV is rare in human. What human can be infected with S-OIV is called as zoonotic swine flu. Pandemic 2009 swine influenza H1N1 virus (2009 H1N1) was emerged in Mexico, America and Canada and spread worldwide. The triple-reassortant H1N1 resulting from antigenic drift was contained with HA, NA and PB1 of human or swine influenza virus, PB2 and PA polymerase of avian influenza virus, and M, NP and NS of swine influenza virus, The 2009 H1N1 enables to transmit to human and swine. The symptoms and signs in human infected with 2009 H1N1 virus are fever, cough and sore throat, pneumonia as well as diarrhea and vomiting. Co-infection with other viruses and bacteria such as Streptococcus pneumoniae can occur high mortality in high-risk population. 2009 H1N1 virus was easily differentiated from seasonal flu by real time RT-PCR which contributed rapid and confirmed diagnosis. The 2009 H1N1 virus was treated with NA inhibitors such as oseltamivir (Tamiflu) and zanamivir (Relenza) but not with adamantanes such as amantadine and rimantadine. Evolution of influenza virus has continued in various hosts. Development of a more effective vaccine against influenza prototypes is needed to protect new influenza infection such as H5 and H7 subtypes to infect to multi-organ and cause high pathogenicity.

• Tuberculosis and Respiratory Diseases
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• v.79 no.2
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• pp.70-73
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• 2016

In late March of 2009, an outbreak of influenza in Mexico, was eventually identified as H1N1 influenza A. In June 2009, the World Health Organization raised a pandemic alert to the highest level. More than 214 countries have reported confirmed cases of pandemic H1N1 influenza A. In Korea, the first case of pandemic influenza A/H1N1 infection was reported on May 2, 2009. Between May 2009 and August 2010, 750,000 cases of pandemic influenza A/H1N1 were confirmed by laboratory test. The H1N1-related death toll was estimated to reach 252 individuals. Almost one billion cases of influenza occurs globally every year, resulting in 300,000 to 500,000 deaths. Influenza vaccination induces virus-neutralizing antibodies, mainly against hemagglutinin, which provide protection from invading virus. New quadrivalent inactivated influenza vaccine generates similar immune responses against the three influenza strains contained in two types of trivalent vaccines and superior responses against the additional B strain.

• Pediatric Infection and Vaccine
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• v.19 no.2
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• pp.61-70
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• 2012

Purpose: This study was performed to compare the clinical characteristics of 2009 pandemic influenza A(H1N1) [A(H1N1) pdm09] and seasonal influenza A infection in the pediatric cancer patients. Methods: A retrospective review was performed in the pediatric cancer patients who had confirmed A(H1N1)pdm09 infection at Samsung Medical Center from August 2009 to February 2010. For the comparison, the medical records of pediatric cancer patients with seasonal influenza A from January 2000 to May 2009 were reviewed retrospectively. Results: Eighty-two A(H1N1)pdm09 infections were confirmed in the pediatric cancer patients. Ten patients (12.2%) developed complicated clinical course by lower respiratory infections or extrapulmonary infections; 4 pneumonia, 1 bronchitis, 1 pericarditis with pneumonia, 1 encephalitis with pneumonia, 2 meningitis and 1 pericarditis. Three patients received mechanical ventilator and ICU care. Three pediatric cancer patients (3.7%) died. The risk factors related to complicated A(H1N1)pdm09 infections were date of infection (44-45th week 2009) and nosocomial infection. When comparing with previous seasonal influenza A infections, more prompt and aggressive antiviral therapy was given in A(H1N1)pdm09 infections. Conclusion: The A(H1N1)pdm09 infections caused a various clinical manifestations including fatal cases in pediatric cancer patient during pandemic season. There was no significant difference in clinical course between influenza A(H1N1)pdm09 and seasonal influenza A infections except the antiviral treatment strategy.

• Journal of Life Science
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• v.30 no.9
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• pp.749-762
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• 2020

Influenza A viruses are circulating in a variety of hosts, including humans, pigs, and poultry. Swine influenza virus is a zoonotic pathogen that can be readily transmitted to humans. The influenza viruses of the 2009 H1N1 pandemic were derived from swine influenza viruses, and it has been suggested that the 1957 H2N2 pandemic and the 1968 H3N2 pandemic both originated in pigs. Pigs are regarded as a mixing vessel in the creation of novel influenza viruses since they are readily infected with human and avian influenza viruses. We isolated three novel H1N2 influenza viruses from pigs showing respiratory symptoms on a Korean farm in 2019. These viruses were reassortants, containing PA and NP genes from those of the 2009 H1N1 influenza virus in addition to PB2, PB1, HA, NA, M, and NS genes from those of triple-reassortant swine H3N2 and classical swine H1N2 influenza viruses circulating in Korean pigs. Mice infected with the isolated H1N2 influenza virus lost up to 17% body weight and exhibited interstitial pneumonia involving infiltration of many inflammatory cells. Results suggest that close surveillance to detect emerging influenza viruses in pigs is necessary for the health of both pigs and humans.

• Tuberculosis and Respiratory Diseases
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• v.70 no.4
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• pp.285-292
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• 2011

After an outbreak of H1N1 influenza A virus infection in Mexico in late March 2009, the World Health Organization raised its pandemic alert level to phase 6, and to the highest level in June 2009. The pandemic H1N1/A influenza was caused by an H1N1 influenza A virus that represents a quadruple reassortment of two swine strains, one human strain, and one avian strain of influenza. After the first case report of H1N1/A infection in early May 2009, South Korea was overwhelmed by this new kind of influenza H1N1/A pandemic, which resulted in a total of 700,000 formally reported cases and 252 deaths. In this article, clinical characteristics of victims of H1N1/A influenza infection, especially those who developed pneumonia and those who were cared for in the intensive care unit, are described. In addition, guidelines for the treatment of H1N1/A influenza virus infection victims in the ICU, which was suggested by the Korean Society of Critical Care Medicine, are introduced.

• Journal of Microbiology and Biotechnology
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• v.20 no.1
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• pp.63-70
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• 2010

Novel influenza A (H1N1) is a newly emerged flu virus that was first detected in April 2009. Unlike the avian influenza (H5N1), this virus has been known to be able to spread from human to human directly. Although it is uncertain how severe this novel H1N1 virus will be in terms of human illness, the illness may be more widespread because most people will not have immunity to it. In this study, we compared the codon usage bias between the novel H1N1 influenza A viruses and other viruses such as H1N1 and H5N1 subtypes to investigate the genomic patterns of novel influenza A (H1N1). Totally, 1,675 nucleotide sequences of the hemagglutinin (HA) and neuraminidase (NA) genes of influenza A virus, including H1N1 and H5N1 subtypes occurring from 2004 to 2009, were used. As a result, we found that the novel H1N1 influenza A viruses showed the most close correlations with the swine-origin H1N1 subtypes than other H1N1 viruses, in the result from not only the analysis of nucleotide compositions, but also the phylogenetic analysis. Although the genetic sequences of novel H1N1 subtypes were not exactly the same as the other H1N1 subtypes, the HA and NA genes of novel H1N1s showed very similar codon usage patterns with other H1N1 subtypes, especially with the swine-origin H1N1 influenza A viruses. Our findings strongly suggested that those novel H1N1 viruses seemed to be originated from the swine-host H1N1 viruses in terms of the codon usage patterns.

• Journal of Korean Clinical Nursing Research
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• v.15 no.3
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• pp.85-94
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• 2009

Purpose: The purpose of this study was to identify the relationship of influenza A (H1N1) knowledge, attitude and practice for nurses. Methods: Data were collected by self-report questionnaires from a total of 325 nurses working in an Influenza A (H1N1) base-zone hospital in C city during September, 2009. The collected data were analyzed using of SPSS/WIN 17.0. Results: The knowledge of influenza A (H1N1) was not statistically different for gender, age, education, work unit, clinical experience, position, or previous education of Influenza A (H1N1). The attitude to influenza A (H1N1) was statistically significant according to age or clinical experience. Practice related to influenza A (H1N1) was statistically different for education, clinical experience or previous education of influenza A (H1N1). Knowledge of influenza A (H1N1) was lowest for etiology and definition compared to other subcategories. Attitude and practice were significantly different for all items. The biggest difference in items was for 'use of physical barriers (protective goggles, face masks and gowns) during procedures that may involve contact with aerosol'. There was a positive association between attitude and practice. Conclusion: An educational program focusing on strategy to change nurses's knowledge, attitude and practice can be effective for infection control in an influenza A (H1N1) base-zone hospital.

• Journal of the Korean Society of School Health
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• v.24 no.1
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• pp.61-70
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• 2011

Purpose: To identify factors associated with children's discriminatory attitudes towards fully recovered children who contracted the 2009 Influenza A (H1N1), in order to provide fundamental information to improve health education for children. Methods: Cross-sectional data were collected from the entire 6th grade classes (N=2,323) of 11 elementary schools randomly selected from 11 school districts in the Seoul Metropolitan Area of South Korea. Questionnaires were used to assess participants' knowledge of and attitudes towards the Influenza A (H1N1) virus. Results: Multiple regression analyses were used to investigate the factors associated with children's discriminatory attitudes toward fully recovered children who had contracted the 2009 Influenza A (H1N1). Multiple regression analysis revealed that perceived risk of contracting and knowledge of 2009 influenza A (H1N1) were significant factors in predicting a child's attitude toward fully recovered Influenza A (H1N1) patients, after controlling for socioeconomic variables. Conclusion: The findings suggests that perceived risk and knowledge play important roles in formulating children's appropriate attitudes towards Novel influenza A (H1N1) patients who are fully recovered from the disease. To promote and maximize children's attitudes in this area, health education needs to be directed at children to reduce excessive concern about contracting the virus and to improve their overall health knowledge.

• Korean Journal of Adult Nursing
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• v.21 no.6
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• pp.593-602
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• 2009

Purpose: This study was to provide baseline data about nurses' Influenza A (H1N1) knowledge, awareness, and practice of infection control and to identify the significant factor affecting the level of practice. Methods: The subjects of this study were 144 nurses who worked at Influenza A (H1N1) regional base Hospital in D city. Data were collected by self-reported questionnaires during September 2009. The collected data were analyzed using SPSS/WIN 12.0 program. Results: The knowledge of Influenza A (H1N1) was statistically different according to age, unit, career and experience of seasonal influenza vaccination during the last year. The awareness of infection control was statistically different according to age, career, experience of seasonal influenza vaccination for last year and intention to get seasonal influenza vaccination for this year. The practice of infection control was statistically different according to unit, experience of seasonal influenza vaccination for last year, intention to get seasonal influenza vaccination for this year and intention to get Influenza A (H1N1) vaccination for this year. There was positive correlation among knowledge, awareness and practice (p < .05). Awareness was the significant factor affecting the level of practice. Conclusion: An educational program focusing on strategy to change nurse's awareness can be effective for infection control of Influenza A (H1N1) in regional base hospitals.

• Tuberculosis and Respiratory Diseases
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• v.68 no.4
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• pp.205-211
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• 2010

Background: Procalcitonin is a well known marker in infection that plays a role in distinguishing between bacterial and viral infections in screening. The aim of the present study was to evaluate the role of procalcitonin in differentiating between 2009 H1N1 influenza pneumonia and community acquired pneumonia of bacterial origin, or mixed bacterial origin and 2009 H1N1 influenza infection. Methods: A retrospective observational study was performed over the 6-month winter period during the 2009 H1N1 influenza pandemic. Ninety-six patient-subjects were enrolled, all of whom had been diagnosed with community acquired pneumonia in emergency department during the study period. On admission, laboratory studies were performed, which included 2009 H1N1 influenza real-time polymerase chain reaction of nasal secretions and procalcitonin on serum; the laboratory values were compared between the study groups. Receiver operating characteristic curve analyses were performed on the resulting data. Results: Compared to those with bacterial or mixed infections (n=62) and bacterial pneumonia with confirmed organisms (n=30), patients with 2009 H1N1 pneumonia (n=34) were significantly more likely to have low procalcitonin levels (p=0.008, 0.001). Using cutoff of value >0.3 ng/mL, the sensitivity and specificity of procalcitonin for detection of patients with confirmed bacterial pneumonia were 76.2% and 60.6%, respectively. A significant difference in procalcitonin was found between 2009 H1N1 pneumonia and pneumonia caused by mixed influenza viral and bacterial infections (0.15 [0.05~0.84] vs. 10.3 [0.05~22.87] ng/mL, p=0.045). Conclusion: Serum procalcitonin measurement may assist in the discrimination between pneumonia of bacterial and of 2009 H1N1 influenza origin. High values of procalcitonin suggest that bacterial infection or mixed infection of bacteria and 2009 H1N1 influenza is more likely.