Epidemiology and virologic investigation of human enterovirus 71 infection in the Republic of Korea from 2007 to 2012: a nationwide cross-sectional study.

BACKGROUND: Enterovirus (EV) 71 is the main pathogen associated with hand, foot and mouth disease (HFMD) or herpangina. Outbreaks of HFMD caused by EV71 infection are associated severe neurological disease and high mortality rates in children. Several sporadic cases of EV71 infection occurred in the Republic of Korea (ROK) in 2000, and EV71 infections were not reported thereafter until 2006. In this prospective study, we report the epidemic and virologic characteristics of the EV71 endemic from 2007 to 2012 in the Republic of Korea. METHODS: We analyzed characteristics of the EV71 infection-associated epidemic from collected specimens and clinical information from 9987 patients with suspected EV infection from the National EV Surveillance System in ROK. To identify the EV71 subgenotype, the homology of viral protein 1 sequences obtained using reverse transcription polymerase chain reaction was compared with the sequences on other countries available from GenBank database. RESULTS: EV71 was detected in 585 (16.7 %) specimens (cerebrospinal fluid, stool or rectal swabs, throat swabs and blood) during study period and was most frequently observed during epidemic seasons in 2009-2012. Major manifestations due to EV71 infection were HFMD (62.2 %) and HFMD with severe neurological complications (28.4 %). Five deaths (0.9 %) due to EV71 infection occurred, with an increased mortality rate during the period after 2009. Most patients (476; 81.4 %) were less than 5 years of age. Analysis of the monthly distribution showed that there was an obvious seasonal pattern to the epidemics, with infections appearing from June to August. The major subgenotype of EV71 isolates circulating in ROK was the C4a strain, which has also appeared in China, Japan and Vietnam. CONCLUSIONS: This surveillance provided valuable data on the epidemic characteristics of EV71 infections in ROK during a 6-year period. Our findings provide data to assist during future outbreaks of EV71 and associated acute neurologic disease.

Enhanced Near-IR Cutting Performance in the Mixture of Cs(x)WO3 and Sb:SnO2 Nanoparticles.

The Cs(x)WO3 nanoparticles were synthesized at 800 degrees C under a reducing ambient, and then milled up to nanoscale by a high-energy ball planetary miller. They showed a single phase, and a mean particle size of 80 nm. The Cs contents (x) in Cs(x)WO3 nanoparticles were optimized to be x = 0.32 to maximize the shielding performance around the wavelength of 1200 nm. To compensate still lower absorption above the wavelength of 1200 nm, they were mixed with Sb-doped SnO2 nanoparticles. Thus we achieved the visible transmittance of 70% at 540 nm and the near-infrared absorption of 80% at 1000 nm and 94% at 1400 nm.

Optical Properties of Yellow EuSi2O2N2 Nanophosphor.

The EuSi2O2N2 nanophoshor was prepared by high-energy planetary mill. The nanophosphor with 100 nm in a mean size showed a broad yellow emission spectrum with the peak at 557 nm and the half width of 61 nm due to Eu2+ f-d transition. Its excitation spectrum was drastically decreased in shorter and longer wavelength sides. The fabricated white-light-emitting diode by a remote-phosphor structure exhibited the better color rendering index than that of the bulkphosphor, which is similar with that with YAG phosphor.

Fabrication of a Functionally Graded Copper-Zinc Sulfide Phosphor.

Functionally graded materials (FGMs) are compositionally gradient materials. They can achieve the controlled distribution of the desired characteristics within the same bulk material. We describe a functionally graded (FG) metal-phosphor adapting the concept of the FGM; copper (Cu) is selected as a metal and Cu- and Cl-doped ZnS (ZnS:Cu,Cl) is selected as a phosphor and FG [Cu]-[ZnS:Cu,Cl] is fabricated by a very simple powder process. The FG [Cu]-[ZnS:Cu,Cl] reveals a dual-structured functional material composed of dense Cu and porous ZnS:Cu,Cl, which is completely combined through six graded mediating layers. The photoluminescence (PL) of FG [Cu]-[ZnS:Cu,Cl] is insensitive to temperature change. FG [Cu]-[ZnS:Cu,Cl] also exhibits diode characteristics and photo reactivity for 365 nm -UV light. Our FG metal-phosphor concept can pave the way to simplified manufacturing of low-cost and can be applied to various electronic devices.

A national cross-sectional study for poliovirus seroprevalence in the Republic of Korea in 2012: implication for deficiency in immunity to polio among middle-aged people.

BACKGROUND: A worldwide poliomyelitis eradication program was initiated in 1988; however, strains of wild poliovirus (WPV) are still endemic in some countries. Until WPV transmission is eradicated globally, importation and outbreaks of WPV are alarming possibilities. This study is the first report to document the polio immunity after 2004, when an inactivated polio vaccine (IPV) was introduced in the Republic of Korea. METHODS: A total of 745 serum samples from randomly selected patients ranging from 6 to 84 years of age were used for neutralization tests, performed in the World Health Organization polio national reference laboratory. RESULTS: Among the 745 tested sera, 439 (58.9%) were seropositive and 19 (2.6%) were seronegative to all PV serotypes. In all age groups, PV3 showed the lowest level of seroprevalence, at 509 cases (68.3%), compared to 616 (82.7%) for PV1 and 685 (91.9%) for PV2. In the 6-10-year age group, which included IPV-immunized children, the highest seropositive rate was observed and the difference in seroprevalence between PV3 and other serotypes was the lowest compared to the other age groups immunized with oral PV vaccines (OPV). In addition, the seronegative rates of all three PV types in children aged 6-10 in this study were found to be lower than those in OPV-immunized children reported in a previous study from the Republic of Korea. Meanwhile, middle-aged subjects (41-60 years) had the lowest seroprevalence and geometric mean titer. CONCLUSIONS: This study indicates a deficiency in immunity to PV in middle-aged individuals, and low seroprevalence to PV3 in all age groups. In addition, due to the ongoing risk of importing PV, middle-aged people should consider PV vaccination before visiting a PV-endemic country. Our findings provide data to assist those involved in deciding future national polio vaccination strategies for the maintenance of a polio-free status in Korea.

Clinical and enterovirus findings associated with acute flaccid paralysis in the Republic of Korea during the recent decade.

Acute flaccid paralysis (AFP) is described as sudden onset of flaccid paralysis in one or more limbs in children caused by polioviruses (PVs). PV eradication is achieved through intensive immunization and AFP attentive surveillance, according to the World Health Organization. Since 1998, the Korea Centers for Disease Control and Prevention has conducted surveillance system. This is an overview of surveillance in the Republic of Korea during the 10-year period from 2002 to 2011. The surveillance system for wild PV eradication was conducted through reporting and laboratory testing. Cell culture isolates were identified by neutralization tests using standard polyclonal antisera typing. The molecular methods were used for further characterization to improve specificity. For genotyping, semi-nested RT-PCR was used to amplify part of the viral protein 1 gene. Patients below 5 years of age accounted for the largest proportion of cases, and a positive association between age and incidence was found. In the total 285 cases, Guillain-Barré syndrome was the major leading causes of AFP. Non-polio enterovirus was detected in some AFP patients. EV71 was detected in 21 cases and Coxsackievirus (C) A2, CA6, CA9, CB2, CB3, CB4, CB5, and Echovirus (E) 25, E30, Sabin strain polio 2, polio 1 and 3 were also detected in some patients. The present study represents a comprehensive 10-year country-based survey of AFP in the Republic of Korea. This surveillance could provide better understanding of the epidemiologic pattern, and clinical manifestations associated with specific genotypes of AFP in the Republic of Korea.

Nationwide surveillance for pathogenic microorganisms in groundwater near carcass burials constructed in South Korea in 2010.

Widespread outbreaks of foot-and-mouth disease and avian influenza occurred in South Korea during 2010. In response to the culling of many animals to attenuate the spread of disease, South Korea used mass burial sites to dispose of the large number of carcasses; consequently, concerns about groundwater contamination by leachate from these burial sites are increasing. Groundwater is one of the main sources of drinking water, and its cleanliness is directly related to public health. Thus, this study aimed to evaluate the safety of groundwater around the burial sites (total of 600 sites). A total of 1,200 groundwater samples were collected though the country, and microbial analysis was conducted during two time periods: during the spring (n = 600; April to June 2012) and after rainfall (n = 600; August to October, 2012; fall). Fecal coliform and Escherichia coli were detected in 173 (14.4%) and 85 (7.1%) of the 1,200 samples, respectively. Salmonella spp. and Shigella spp. each were detected only once (0.083%). Clostridium perfringens was detected from 7 groundwater samples (0.583%), and E. coli O157:H7 was not detected. With respect to norovirus, only the GII type was detected from six groundwater samples (0.5%), and enterovirus was detected in 15 groundwater samples (1.25%). The frequency of E. coli that we detected was lower than that found in previous studies conducted in South Korea, but we detected higher frequency of fecal coliform than that observed in a previous report. The contamination frequencies of Salmonella spp. and Shigella spp. were very low, but C. perfringens, which could be an indicator of fecal pollution, was detected in seven regions. Overall, the results of the present study indicate a low possibility of contamination from burial sites. However, consistent monitoring is required to prevent microbial contamination of groundwater near the burial sites.

Molecular characteristics of human coxsackievirus B1 infection in Korea, 2008-2009.

This study was performed to analyze epidemiological and molecular characteristics of coxsakievirus (CV) B1 infection associated with severe neonatal illness cases and death in Korea during 2008-2009. Through a nationwide surveillance program, specimens were collected from 104 patients infected with CVB1. The detection of enteroviruses (EVs) from specimens was subjected to a diagnostic real-time polymerase chain reaction (RT-PCR) in the 5'-non-coding region (NCR). A semi-nested PCR was conducted to amplify sequences from the VP1 region and sequence comparison was performed with reference strains registered in Genbank. Male-to-female ratio confirmed approximately 5:4. The major clinical manifestation of patients infected with CVB1 was aseptic meningitis (55.8%). The other clinical symptoms were herpangina or hand-foot-mouth disease (22.1%) and neonatal sepsis (7.7%). The sequences of CVB1 isolates were divided into four genetic clusters (A-D) with at least 15% diversity between the clusters. Almost all the CVB1 isolates in Korea from 2008 to 2009 were in cluster D (except for 2 cases). The homology relationship was also similar between the Korean CVB1 strains and US strain (above 93%). It is possible that Korean CVB1 isolates found during 2008-2009 originated from the US strains found during 2006-2008. The identification of CVB1 in South Korea shows the potential of EVs to cause serious disease in an unpredictable fashion.

Nationwide groundwater surveillance of noroviruses in South Korea, 2008.

To inspect the norovirus contamination of groundwater in South Korea, a nationwide study was performed in the summer (June to August) and winter (October to December) of 2008. Three-hundred sites designated by the government ministry were inspected. Water samples were collected for analysis of water quality, microorganism content, and viral content. Water quality was assessed by temperature, pH, turbidity, residual chlorine, and nitrite nitrogen content. Microorganism contents were analyzed bacteria, total coliforms, Escherichia coli, and bacteriophage. Virus analyses included panenterovirus and norovirus. Two primer sets were used for the detection of norovirus genotypes GI and GII, respectively. Of 300 samples, 65 (21.7%) were norovirus positive in the summer and in 52 (17.3%) were norovirus positive in the winter. The genogroup GI noroviruses that were identified were GI-1, GI-2, GI-3, GI-4, GI-5, GI-6, and GI-8 genotypes; those in the GII genogroup were GII-4 and GII-Yuri genotypes. The analytic data showed correlative relationships between the norovirus detection rate and the following parameters: water temperature and turbidity in physical-chemical parameters and somatic phage in microbial parameters. It is necessary to periodically monitor waterborne viruses that frequently cause epidemic food poisoning in South Korea for better public health and sanitary conditions.

High level of sequence variation in the 3' noncoding region of Japanese encephalitis viruses isolated in Korea.

The 3' noncoding region (NCR) of Japanese encephalitis (JE) viruses isolated in Korea and Nakayama-NIH strain have been sequenced and compared with the 3' NCR sequences of other JE isolates reported previously. Sequence alignment of about 60 nucleotides (based on consensus sequence number) immediately downstream of the open reading frame (ORF) stop codon in the 3' NCR of the Korean isolates showed high degree of sequence variation and deletion; thus, this region was termed as the variable region. However, in the predicted RNA secondary structures, a similar type loop exists at the 5'-terminus of the 3' NCR of JE viruses, despite low level of sequence homology (22%) and deletion in the variable region. The phylogenetic tree based on the 3' NCR sequences of JE viruses including the variable region showed a similar pattern to that based on envelope genes; in that, there are two genetically different types of JE viruses in Korea. Therefore, the variable region would be a useful genetic marker for JE viruses.