Koh S.-J.,Epidemic Intelligence Service |
Cho H.G.,Gyeonggi do Institute of Health and Environment |
Kim B.H.,Bundang Jesaeng General Hospital |
Choi B.Y.,Hanyang University
Journal of Korean Medical Science | Year: 2011
In January 2008, an outbreak of acute gastroenteritis at a waterpark was reported to the Bundang-gu Public Health Center in Seongnam, Korea. To determine the etiological agent and mode of transmission, a retrospective cohort study was done using structured questionnaires and stool samples from patients who had current gastrointestinal symptoms and three food handlers were tested. A total of 67 (31.0%) students and teachers developed acute gastroenteritis. No food items were associated with an increased risk of the illness. Norovirus was detected in 3 stool specimens collected from 6 patients who had severe diarrhea using semi-nested RT-PCR. All the specimens contained the genogroup I strains of the norovirus. Norovirus was also detected in the groundwater samples from the waterpark. In the nucleotide sequencing analysis, all the genogroup I noroviruses from the patients and groundwater samples were identified as the norovirus genotype I-4 strain. They were indistinguishable by DNA sequencing with a 97% homology. We conclude the outbreak of acute gastroenteritis caused by the norovirus was closely related to the contaminated groundwater. © 2011 The Korean Academy of Medical Sciences.
Kim T.-S.,Korea University |
Jeong J.-Y.,Gyeonggi do Institute of Health and Environment |
Wells G.F.,Eawag - Swiss Federal Institute of Aquatic Science and Technology |
Park H.-D.,Korea University
Applied Microbiology and Biotechnology | Year: 2013
Temporal variation of general and rare bacterial taxa was investigated using pyrosequencing of 16S rRNA gene from activated sludge samples collected bimonthly for a two-year period. Most of operational taxonomic units (OTUs) were allocated to rare taxa (89.6%), but the rare taxa comprised a small portion of the community in terms of abundance of sequences analyzed (28.6%). Temporal variations in OTUs richness significantly differed between the two taxa groups in which the rare taxa showed a higher diversity and a more fluctuating pattern than the general taxa. Furthermore, the two taxa groups were constrained by different explanatory variables: influent BOD, effluent BOD, and DO were the significant (P < 0.05) parameters affecting the pattern of the general taxa, while temperature was the factor for the rare taxa. Over the test period, the general taxa persisted for a longer time (i.e.; lower turnover rate) in the bioreactor than the rare taxa. In conclusion, this study demonstrated clear differences in temporal dynamic patterns for the general and rare bacterial taxa in an activated sludge bioreactor, which would be a foundation for better understanding the bacterial ecology of activated sludge. © 2012 Springer-Verlag.
Heo J.,Gyeonggi do Institute of Health and Environment |
Lee G.,Hankuk University of foreign Studies
Science of the Total Environment | Year: 2014
The collection of 2,3,7,8-substituted polychlorinated dibenzo-ρ-dioxins and dibenzo furans (PCDDs/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) using a polyurethane form (PUF)-disk passive air sampler (PAS) was investigated in urban-residential and industrial areas. This was performed to assess the feasibility of using this method as an alternative to an active air sampler (AAS). The PUF-disk PAS was exposed to ambient air over a period of 37-370 and 57-173days in urban and industrial areas, respectively, together with AASs. The sum of total toxic equivalent quantity (TEQ) σPCDDs/Fs and σdl-PCB was typically high in the industrial area, with values within the range 0.171-0.635pg-TEQ/m3, and 0.037-0.300pg-TEQ/m3 in the urban-residential area. To derive the time-weighted average (TWA) concentration from the PAS data accurately, it was estimated that the PAS deployed for less than 80days was adequate to maintain linear accumulation conditions. PCDDs/Fs are mainly particle bound and showed low average uptake rates of 1.4m3d-1, while dl-PCBs were slightly higher with 2.0m3d-1 because of its high vapor pressure. Most of the congener concentrations measured using the PAS and AAS were within a factor of two, indicating that PASs can be used to monitor spatial and temporal variations in the concentrations of persistent organic pollutants (POPs) in the atmosphere. © 2014 Elsevier B.V.
Kim D.-G.,Gyeonggi do Institute of Health and Environment |
Choi K.-I.,Korea Institute of Ceramic Engineering And Technology |
Lee D.-H.,University of Seoul
Atmospheric Research | Year: 2011
To evaluate their behavior and gas-particle partitioning, the concentrations of dioxin-like polychlorinated biphenyls (dl-PCBs) in both gas and particle phases in ambient air were measured at urban sites in Gyeonggi-do, South Korea. The predominance of gas-phase PCBs in the atmosphere was more significant during summer at all sites. In July, approximately 92% of the total toxic equivalent quantity (TEQ) was in the gaseous phase, whereas in January, approximately 96% of the total TEQ was in the particle phase. The dl-PCBs can be transported over long ranges and accumulate rapidly in plants at warm temperatures. Partial vapor pressures of dl-PCBs were well correlated with temperature and the steep slopes obtained from Clausius-Clapeyron plots indicated that the volatilization of dl-PCBs from surfaces in the local surroundings of the sampling sites dominated the atmospheric concentrations.The gas-particle distribution was also examined through several different approaches such as the log KP-log PL o, log KP-log KOA, Junge-Pankow, and KOA-based models. The slopes obtained from regressing log KP versus log PL o (log KP versus log KOA) were smaller than -1 (or 1). The particle-bound fraction (φ) and KP of the dl-PCB congeners were estimated using the Junge-Pankow and KOA-based models. Both models tended to overestimate the φ and KP values of the dl-PCB congeners compared to those obtained from field measurements. Nevertheless, the coefficients of determination (r2) between the experimental and modeled KP values were 0.74 to 0.84 and 0.76 to 0.84 for the Junge-Pankow and KOA-based models, respectively. © 2011 Elsevier B.V.
Lee S.-G.,Chonbuk National University |
Cho H.-G.,Gyeonggi do Institute of Health and Environment |
Paik S.-Y.,Catholic University of Korea
BMB Reports | Year: 2015
Norovirus is a major cause of viral gastroenteritis and a common cause of foodborne and waterborne outbreaks. Norovirus outbreaks are responsible for economic losses, most notably to the public health and food industry field. Norovirus has characteristics such as low infectious dose, prolonged shedding period, strong stability, great diversity, and frequent genome mutations. Besides these characteristics, they are known for rapid and extensive spread in closed settings such as hospitals, hotels, and schools. Norovirus is well known as a major agent of food-poisoning in diverse settings in South Korea. For these reasons, nationwide surveillance for norovirus is active in both clinical and environmental settings in South Korea. Recent studies have reported the emergence of variants and novel recombinants of norovirus. In this review, we summarized studies on the molecular epidemiology and nationwide surveillance of norovirus in South Korea. This review will provide information for vaccine development and prediction of new emerging variants of norovirus in South Korea. © 2015 by the The Korean Society for Biochemistry and Molecular Biology.