• Journal of Preventive Medicine and Public Health
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• 제19권2호
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• pp.281-292
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• 1986

Infection by hepatitis B virus is one of the major health problems of this nation. HBsAg positive rates of general population and school children were known to be as about 8 percent and 3.9 to 5.9 percent respectively. To study the incidence rate of hepatitis B infection in school children of rural area, author had examined 475 school children of relatively isolated agricultural area for baseline prevalence of hepatitis B virus serologic markers and followed up 415 school children during 10 months to determined the frequency of serologic conversion. The major results are summarized as followings: 1) Among the 278 susceptible children who were followed up, 26 had seroconversion for HBsAg or Anti-HBs. Therefore, the cumulative incidence rate during 10 months is estimated 9.4%. 2) The incidence rate of hepatitis B infection tends to increase with age (6-9yrs: 3.2%, 10-14yrs: 9.5%, 15-17yrs: 18.9%), and the incidence rate in male (13.0%) was higher than in female (5.7%). 3) The incidence rates of hepatitis B virus infection were not different statistically among three economic classes (The rates of lower, middle and higher class were 11.8%, 7.1% and 10.5%.). 4) The incidence rates of hepatitis B virus infection were not different statistically between visitors and non-visitors of clinic or hospital, dental clinic, persons received IV and not received IV, and persons with familial history and without familial history of liver diseases. Therefore all of these factors were not identified as risk factor of hepatitis B virus infection. And the transmissibility within the class of school was not recognized, too. 5) Among the 25 children who were HBsAg positive when enrolled, 15 (60%) were still HBsAg positive, who were identified as chronic carrier 15 of 415 school children were chronic carriers, then chronic carrier rate was estimated 3.6%, and there was no difference between sexes. 6) Of 38 children who had been Anti-HBs positive when enrolled, 5 (13.2%) lost Anti-HBs. Therefore, the loss rate of Anti-HBs per year is estimated to be 15.8%.

• Journal of Preventive Medicine and Public Health
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• 제35권1호
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• pp.65-71
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• 2002

Objective : To estimate the status of HIV infection and AIDS incidence using a back-calculation model in Korea. Methods : Back-calculation is a method for estimating the past infection rate using AIDS incidence data. The method has been useful for obtaining short-term projections of AIDS incidence and estimating previous HIV prevalence. If the density of the incubation periods is known, together with the AIDS incidence, we can estimate historical HIV infections and forecast AIDS incidence in any time period up to time t. In this paper, we estimated the number of HIV infections and AIDS incidence according to the distribution of various incubation periods Results : The cumulative numbers of HIV infection from 1991 to 1996 were $708{\sim}1,426$ in Weibull distribution and $918{\sim}1,980$ in Gamma distribution. The projected AIDS incidence in 1997 was $16{\sim}25$ in Weibull distribution and $13{\sim}26$ in Gamma distribution. Conclusions : The estimated cumulative HIV infections from 1991 to 1996 were $1.4{\sim}4.0$ times more than notified cumulative HIV infections. Additionally, the projected AIDS incidence in 1997 was less than the notified AIDS cases. The reason for this underestimation derives from the very low level of HIV prevalence in Korea, further research is required for the distribution of the incubation period of HIV infection in Korea, particularly for the effects of combination treatments.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제19권2호
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• pp.137-170
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• 2015

In this paper, we propose and analyze three viral infection models with humoral immunity including an eclipse stage of infected cells. The incidence rate of infection is represented by bilinear incidence and saturated incidence in the first and second models, respectively, while it is given by a more general function in the third one. The neutralization rate of viruses is giv0en by bilinear form in the first two models, while it is given by a general function in the third one. For each model, we have derived two threshold parameters, the basic infection reproduction number which determines whether or not a chronic-infection can be established without humoral immunity and the humoral immune response activation number which determines whether or not a chronic-infection can be established with humoral immunity. By constructing suitable Lyapunov functions we have proven the global asymptotic stability of all equilibria of the models. For the third model, we have established a set of conditions on the threshold parameters and on the general functions which are sufficient for the global stability of the equilibria of the model. We have performed some numerical simulations for the third model with specific forms of the incidence and neutralization rates and have shown that the numerical results are consistent with the theoretical results.

• The Korean journal of internal medicine
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• 제39권3호
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• pp.513-523
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• 2024

Background/Aims: Since the coronavirus disease 2019 (COVID-19) outbreak, hospitals have implemented infection control measures to minimize the spread of the virus within facilities. This study aimed to investigate the impact of COVID-19 on the incidence of healthcare-associated infections (HCAIs) and common respiratory virus (cRV) infections in hematology units. Methods: This retrospective study included all patients hospitalized in Catholic Hematology Hospital between 2019 and 2020. Patients infected with vancomycin-resistant Enterococci (VRE), carbapenemase-producing Enterobacterales (CPE), Clostridium difficile infection (CDI), and cRV were analyzed. The incidence rate ratio (IRR) methods and interrupted time series analyses were performed to compare the incidence rates before and after the pandemic. Results: The incidence rates of CPE and VRE did not differ between the two periods. However, the incidence of CDI increased significantly (IRR: 1.41 [p = 0.002]) after the COVID-19 pandemic. The incidence of cRV infection decreased by 76% after the COVID-19 outbreak (IRR: 0.240 [p < 0.001]). The incidence of adenovirus, parainfluenza virus, and rhinovirus infection significantly decreased in the COVID-19 period (IRRs: 0.087 [p = 0.003], 0.031 [p < 0.001], and 0.149 [p < 0.001], respectively). Conclusions: The implementation of COVID-19 infection control measures reduced the incidence of cRV infection. However, CDI increased significantly and incidence rates of CPE and VRE remained unchanged in hematological patients after the pandemic. Infection control measures suitable for each type of HCAI, such as stringent hand washing for CDI and enough isolation capacities, should be implemented and maintained in future pandemics, especially in immunocompromised patients.

• Journal of Korean Biological Nursing Science
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• 제11권2호
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• pp.114-119
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• 2009

Purpose: The effectiveness of an infection control program is important to hospital quality improvement and decreases of mortality rate and prevalence. Methicillin resistant Staphylococcus aureus (MRSA) is the most common pathogen causing nosocomial infection. The aim of the study was to identify the most important risk factors for acquiring an MRSA, to evaluate the MRSA incidence rates after the nursing intervention in Neurosurgery intensive care unit (ICU). Methods: Clinical data were collected prospectively from December 2008 until July 2009 in Neurosurgery ICU. The patients were divided into preintervention and postintervention groups. An infection was defined as an MRSA if it occurred 48 hr after admission to the Unit. Infection control program including hand washing, education of health care workers about MRSA, standard precaution and contact isolation of patients were applied for three month. Results: A total of 85 patients were included in the study. Forty-five patients of S. aurerus were detected. Among 45 of S. aurerus, MRSA were isolated from 38 patients. The incidence MRSA rate of postintervention group was 26.9% while incidence MRSA rate of preintervention group was 66.7%. In total, The incidence MRSA rate was 44.7%. The incidence of MRSA have decreased in the postintervention as compared with the preintervention group. Conclusion: The infection control program for MRSA was effective to decrease the MRSA isolation rate. The health care workers regular hand washing, education of nosocomial infection control is important enough to be emphasized.

• Journal of Gastric Cancer
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• 제18권4호
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• pp.328-338
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• 2018

The incidence of gastroesophageal junction adenocarcinoma (GEJAC) in Western countries has increased in recent decades, in addition to a rise in the incidence of esophageal adenocarcinoma (EAC). Gastroesophageal reflux disease (GERD), obesity, smoking, alcohol consumption, and low Helicobacter pylori (HP) infection rate have been nominated as risk factors for such cancers. Among these risk factors, the increased prevalence of GERD and obesity and the decreased prevalence of HP infection are of special interest owing to the currently increasing prevalence of GEJAC in Western countries. Although similar trends in the prevalence of GERD, obesity, and HP infection are observed in Asian countries after a time lag from Western countries, it is still uncertain if the prevalence of GEJAC in Asian countries is increasing, especially in Korea. The incidence of GERD in Korea is currently increasing; it was below 3% in the 1990s. The incidence of obesity in the Korean population is increasing owing to the adoption of westernized lifestyles, including food preferences, and the HP infection rate in Korea is known to be decreasing. Therefore, based on logical extrapolation of observations of Western countries, the incidence of GEJAC will increase in Korea. However, the proportion of GEJAC among other upper gastrointestinal malignancies in Korea appears to be currently unchanged compared with that in the 1990s. Presently, there is a lack of epidemiologic studies on this issue in this region; therefore, more studies are needed to clarify the characteristics of these tumors and to improve clinical outcomes for patients with these tumors.

• 성인간호학회지
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• 제21권4호
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• pp.435-445
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• 2009

Purpose: This study was to examine whether VRE infection control strategies have an effect on the decrease in incidence rates for VRE acquisition and VRE nosocomial infection in ICU. Methods: All the patients were examined for VRE carriers on ICU admission. Among them, patients hospitalized for over 48 hours were investigated for VRE acquisition rates and VRE nosocomial infection rate using VRE infection control strategies in ICU for the experimental group from September 2007 to April 2008. Before that, incidence of VRE acquisition and VRE nosocomial infection for the control group without Intervention were investigated from May to August 2007 retrospectively. Results: VRE acquisition rate in clinical specimens was 0.6% in the experimental group, that was significantly lower when compared to the control group. VRE carrier rate at admission to ICU was 15.4%. Out of 182 VRE carriers, 180 patients were identified by the active surveillance culture. Conclusion: These results suggested that active surveillance culture at admission was considered to be an essential measure for detection of VRE carrier. But without strict isolation and adherence rating after each intervention, hand washing and contact isolation alone did not significantly decrease VRE nosocomial infection, although it did significantly decrease incidence of VRE acquired from clinical specimen.

• Childhood Kidney Diseases
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• 제21권2호
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• pp.101-106
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• 2017

Purpose: The aim of this study was to analyze the incidence and microbiological characteristics of urinary tract infection in infants aged younger three months and to compare with other infection with positive urine culture. Methods: We retrospectively reviewed the medical records of 425 infants with a tympanic temperature >$37.6^{\circ}C$, aged younger than three months, who were admitted to Cheil General Hospital in Seoul, Korea, from January 2013 to December 2016. Demographic and clinical features, laboratory findings, respiratory virus PCR and the pathogens of a urine culture were analyzed. Results: A total of 88 infants (63 males, 25 females) had urinary pathogens detected in the urine culture test. The incidence of UTI in febrile infants aged younger 3 months was 11%. The most common pathogen which causes UTI was E. coli as same as in previous studies. They were divided into a UTI group (n=48) and a non-UTI group (n=40). In comparison of both group, leukocytosis, C-reactive protein level, Absolute neutrophil count level, peak temperature is statistically significant. In both group, there were co-infections with viral pathogens in some cases, and the odd ratio of non-UTI group with viral infection was 3.28. Conclusion: The study determined the incidence and pathogen of UTI in febrile infants, aged younger three months. E. coli was responsible for the majority UTI. There were some viral co-infections in febrile infants with bacteriuria and incidence was higher in non-UTI group. WBC count, ANC count and CRP level were the differentiating factors of UTI from non-UTI group.

• Journal of Mycology and Infection
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• 제23권4호
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• pp.99-104
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• 2018

Background: Trichophyton verrucosum (T. verrucosum) is a zoophilic dermatophyte that causes ringworm in cattle and is prevalent worldwide. This dermatophyte may be responsible for various conditions, especially inflammatory skin lesions. Objective: In this study, we aimed to investigate the changes in the clinical and epidemiological characteristics of T. verrucosum infections in southeastern Korea. Methods: A total of 34 patients who visited the Catholic Skin Clinic and the Kyungpook National University Hospital in Daegu, Korea from 2005 to 2017 were diagnosed with T. verrucosum infection. The diagnosis was confirmed using fungal culture. The data were based on a retrospective survey of the medical records. Results: The annual incidence of T. verrucosum infection was very low. There was no difference in the sexual incidence. T. verrucosum infection was most common among subjects in their fifties and sixties. The highest incidence was during the month of September. The arm was most frequently involved, followed by the face. This infection was predominant in patients living in rural areas. Conclusion: These clinicoepidemiological findings provide useful information for understanding the changes in the infection caused by T. verrucosum. In particular, it was interesting to note that the incidence was very low, majority of the affected subjects were in their fifties and sixties, and the most commonly affected site was the arm.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제34권3호
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• pp.365-369
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• 2008

This study analyzed the incidence of wound infection after the operation of mandibular third molar extraction in relation with antibiotic prophylaxis with the object of young and healthy patients. The study object was 1,177 mandibular third molars of 850 men of 20 to 25 years old without any specific systemic disease. Three methods of preventive antibiotic medication were selected according to the preventive antibiotic medication previously reported; three experimental groups were selected based on them, and the antibiotic used was amoxicillin($^{(R)}Kymoxin$, Yuhanyanghaeng, Seoul). The group 1 includes the patients that took the antibiotic orally before the operation(one hour earlier, 500mg) and for three days after the operation(250mg per time, three times/day), the group 2 is the ones that took the same antibiotic orally only once about one hour before the operation(500mg), and the group 3 did not take any antibiotics before and after the operation. And to compare the difficulties and the degrees of extraction during operations which can be possibly related to the wound infection after the operations, the mandibular third molars' impacted depths and extraction methods were investigated as well. To check if the wound was infected, observations with an internal of one week were performed twice after the operation, and the meaningfulness of the infection incidence was verified through Chi-square test using SPSS program(SPSS Inc., IL, USA). There was no statistically significant difference between the antibiotic medication methods and the wound infection incidence after the operation among the experimental groups. As examining the relations between the mandibular third molar operation methods and the wound infection incidence after the operation, there existed a statistically meaningful difference in the infection incidence according to the operation methods(p=0.020). And there was no statistically significant difference in the wound infection incidence according to the impacted depth of the mandibular third molar. Therefore, it is thought that there exists little necessity of prophylatic antibiotics medication when extracting the mandibular third molar of young and healthy men without any systemic disease in general; however, in case when it is expected that the possibility of infection will be high or the wound on the tissue will be severe, it is sure that the prophylactic antibiotics medication will be necessary.