• 한국입자에어로졸학회지
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• 제6권2호
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• pp.81-90
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• 2010

Several studies have suggested the possibility of airborne transmission of infectious diseases such as tuberculosis, pandemic influenza. because the number of patients increases explosively, if infectious disease had a high basic reproduction number, pharmaceutical interventions such as vaccination, chemoprophylaxis in the early stage of epidemic. Thus, non-pharmaceutical interventions such as mask-wearing, installing air cleaners, school closure are important to control and prevent the infectious diseases. However, the current technology on the mask, air cleaning, ventilation, and etc., seems to be not originated from the understanding of infection via airborne transmission. It is important to estimate the aerodynamic behavior of saliva droplets by coughing or speaking in order to understand the phenomena of airborne infection. In addition, the prediction of transmission of infectious diseases through the air is critical to prevent or minimize the damage of infection. In this review, we reviewed the recent studies on the airborne infection by focusing on the aerodynamic characteristics of saliva droplets and modeling of airborne transmission.

• 식물병연구
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• 제19권2호
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• pp.114-117
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• 2013

To facilitate their spread, plant viruses have developed several methods for dispersal including insect and seed transmission. While insect transmission requires virus stability against insect digestion, seed-transmitted viruses have to overcome barriers to entry into embryos. Bean pod mottle virus (BPMV) is transmitted through seed at levels typically below 0.1%, but co-infection with Soybean mosaic virus (SMV) enhanced the seed transmission rate of BPMV in one experiment. In contrast, the rate of SMV seed transmission was not affected by BPMV co-infection. In a second preliminary study, the rate of SMV transmission was lower in an isoline of Williams 82 that contained a null mutation for the Kunitz trypsin inhibitor gene than in Williams 82. In this preliminary study, we observed that factors such as protease inhibitor expression and dual infection may affect the frequency of seed transmission of BPMV and SMV.

• Tuberculosis and Respiratory Diseases
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• 제79권4호
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• pp.201-206
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• 2016

Active tuberculosis (TB) has a greater burden of TB bacilli than latent TB and acts as an infection source for contacts. Latent tuberculosis infection (LTBI) is the state in which humans are infected with Mycobacterium tuberculosis without any clinical symptoms, radiological abnormality, or microbiological evidence. TB is transmissible by respiratory droplet nucleus of $1-5{\mu}m$ in diameter, containing 1-10 TB bacilli. TB transmission is affected by the strength of the infectious source, infectiousness of TB bacilli, immunoresistance of the host, environmental stresses, and biosocial factors. Infection controls to reduce TB transmission consist of managerial activities, administrative control, engineering control, environmental control, and personal protective equipment provision. However, diagnosis and treatment for LTBI as a national TB control program is an important strategy on the precondition that active TB is not missed. Therefore, more concrete evidences for LTBI management based on clinical and public perspectives are needed.

• Asian-Australasian Journal of Animal Sciences
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• 제6권3호
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• pp.331-337
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• 1993

In order to understand the effect of duck hepatitis B virus (DHBV) on the economic performance of ducks, Three groups (DHBV congenitally infected, experimentally infected and DHBV negative) Brown Tsaiya ducks (Anas platyrhyncha) were used for experimental animals. Artificial insemination and pedigree hatching were applied in the propagation of ducklings, and the efficiency of vertical transmission and experimental infection was analyzed through the detection of DHBV DNA in the sera of 8-week-old offspring. The observation of the records of the first year indicated that the persistent infection had no significant effects on the performance of ducks, except the egg number of survival ducks up to 40 week of age. Thus DHBV infection did not appear to give ill effects to the economic performance of ducks in first laying year. A higher infection rate (85.3%) was obtained in congenital transmission than that (75.5%) of experimental infection. Both modes of infection did not reach 100% infectious rate, although some ducks developed transient viraemia in a tracing of DHBV DNA for 24 weeks to 11 challenged ducklings.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제19권2호
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• pp.83-95
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• 2016

Hepatitis C virus (HCV) infection is a major medical challenge affecting around 200 million people worldwide. The main site of HCV replication is the hepatocytes of the liver. HCV is a positive enveloped RNA virus from the flaviviridae family. Six major HCV genotypes are implicated in the human infection. In developed countries the children are infected mainly through vertical transmission during deliveries, while in developing countries it is still due to horizontal transmission from adults. Minimal nonspecific and brief symptoms are initially found in approximately 15% of children. Acute and chronic HCV infection is diagnosed through the recognition of HCV RNA. The main objective for treatment of chronic HCV is to convert detected HCV viremia to below the detection limit. Children with chronic HCV infection are usually asymptomatic and rarely develop severe liver damage. Therefore, the benefits from current therapies, pegylated-Interferon plus ribavirin, must be weighed against their adverse effects. This combined treatment offers a 50-90% chance of clearing HCV infection according to several studies and on different HCV genotype. Recent direct acting antiviral (DAA) drugs which are well established for adults have not yet been approved for children and young adults below 18 years. The most important field for the prevention of HCV infection in children would be the prevention of perinatal and parenteral transmission. There are areas of focus for new lines of research in pediatric HCV-related disease that can be addressed in the near future.

• Journal of Preventive Medicine and Public Health
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• 제29권2호
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• pp.331-346
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• 1996

Exploring the epidemiological trend of HIV/AIDS is required for making the national AIDS policy. In this study, the trend of HIV/AIDS incidence, rout of transmission and some characteristics of AIDS for the past 11 years in Korea using the reported cases from the national STD screening scheme were reviewed. Based on the results, the trend of main route of transmission according to the year was established by stage and the HIV/AIDS cases in this year was estimated and that to the year 2000 was projected by 'Epimodel' programme. The results were as follows : 1. Of the total infected persons, 76% were in their twenties and thirties, socioeconomically and sexually active age groups. While the transmission by sexual contact overseas was decreasing, the infection through domestic heterosexual and homosexual contact was increasing. 2. In the middle of the 1980's, the infected persons were mainly prostitutes infected through heterosexual contact with the HIV positive foreigner in this county(stage 1). And in the late of the 1980's the main source of infection was the sexual contact overseas and the domestic heterosexual contact(stage 2). Since the early of the 1990's, the infection through the heterosexual contact with non-regular sexual partner in this country has increased rapidly(stage 3), which was the evidence of the possibility of HIV epidemics. After that, it was expected that the infection through the homosexual contacts, the heterosexual contacts with commercial sex workers outside and the non-regular sexual contact inside of this country would increase continuously. In the result, the occurrence of neonatal infection by vertical transmission was expected(stage4). 3. The number of HIV/AIDS was estimated at 572 to 2,313 and the projected number of HIV/AIDS to the you 2000 was around 5,800 including 627 AIDS patients. For the further study on the estimation and projection of HIV/AIDS, it was suggested that the sampling survey on the HIV infection rate in the high risk groups and the sentinel hospital surveillance system should be conducted.

• Journal of Preventive Medicine and Public Health
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• 제42권6호
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• pp.408-415
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• 2009

Objectives : This study was performed to investigate the mumps transmission control status and inapparent infection rate among middle and high school students in Daegu City during a mumps outbreak. Methods : Nine schools (two middle schools and seven high schools), which reported a number of mumps cases between 2007 and 2008 were selected for investigation. During March-May 2008, a standard questionnaire was distributed to gather information about case identification, instructed isolation measure, isolation status of mumps cases and related factors, and outdoor activities of nonisolated mumps case. Inapparent infection rate was estimated by serum mumps IgM and IgG antibodies status and self-reported mumps symptoms in three of the nine schools. Results : Among 2,560 respondents, more than half of students answered that they did not receive instructions in mumps transmission control measures during the outbreak. Among the 327 mumps cases identified by the questionnaire, 131 cases (40.1%) were considered as isolated and the isolation rates were significantly different among schools, grades, and gender. Of the non-isolated cases, 88.3% continued attending school. Inapparent mumps infection rates were between 56.3% and 70.2%. Conclusions : Mumps transmission control was inadequate to control the mumps outbreak. Although high inapparent infection rate would mitigate the transmission control effect of case isolation, this measure is fundamental for infection control. The reasons of this inadequate status need to be explored to develop an effective intervention strategy.

• 대한간호학회지
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• 제37권6호
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• pp.976-985
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• 2007

Purpose: The aim of this study was to identify the present situation of hospital infection and route of infection by clarifying the transmission aspect of methicillin-resistant Staphylococcus aureus(MRSA) in a Neurosurgical Intensive Care Unit by analysing genotype. Methods: MRSA was cultured from twenty five patients with a tracheostomy, twenty five health care workers, and environments in the Neurosurgical Intensive Care Unit of one hospital in D city. Data was collected from December 21, 2004 to November 5, 2005. MRSA isolates representing each genotype were analyzed by spaA typing and a multiplex PCR method capable of identifying the structural type of the staphylococcal cassette chromosome mec(SCCmec) carried by the bacteria. Results: As the same genotype and gene sequence were found among health care workers, patients, and environments, it was assumed that there was cross transmission among them. Conclusion: This study suggests that first, as the hospital infection by MRSA between health care workers and patients in the Neurosurgical Intensive Care Unit was due to result of cross transmission and the relevance of transmission between them was verified, it is necessary to take preventive measures and conduct education. Secondly, development of nursing interventions and study of infection are needed. Thirdly, consistent investment in prevention against hospital infections and environmental renovation is needed.

• 대한의용생체공학회:의공학회지
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• 제15권3호
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• pp.295-304
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• 1994

This paper describes some preliminary attempts to formulate simple mathematical models of the transmission dynamics of HIV infection in homosexual communities. In conjunction with a survey of the available epidemiological data on HIV infection and the incidence of AIDS, the model is used to assess how various processes influence the course of the initial epidemic following the introduction of the virus. Models of the early stages of viral spread provide crude methods for estimating the basic reproductive rate of the virus, given a knowledge of the incubation period of AIDS and the initial doubling time of the epidemic. More complex models are formulated to assess the influence of heterogeneity in sexual activity. This latter factor is shown to have a major effect on the predicted pattern of the epidemic.

• Biomolecules & Therapeutics
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• 제22권2호
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• pp.93-99
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• 2014

The interaction between viral HA (hemagglutinin) and oligosaccharide of the host plays an important role in the infection and transmission of avian and human flu viruses. Until now, this interaction has been classified by sialyl(${\alpha}2-3$) or sialyl(${\alpha}2-6$) linkage specificity of oligosaccharide moieties for avian or human virus, respectively. In the case of H5N1 and newly mutated flu viruses, classification based on the linkage type does not correlate with human infection and human-to-human transmission of these viruses. It is newly suggested that flu infection and transmission to humans require high affinity binding to the extended conformation with long length sialyl(${\alpha}2-6$)galactose containing oligosaccharides. On the other hand, the avian flu virus requires folded conformation with sialyl(${\alpha}2-3$) or short length sialyl(${\alpha}2-6$) containing trisaccharides. This suggests a potential future direction for the development of new species-specific antiviral drugs to prevent and treat pandemic flu.