The present study has determined the detection rate of norovirus (NoV) with acute gastroenteritis (AGE) in hospitalized children and describes the molecular epidemiology of NoV circulating in Seoul, Korea. Six hundred and eighty-three (9.8%) of samples were positive for NoV. Of these, the NoV GII genogroup was the most commonly found, with a prevalence of 96.2% (683 of 710). Only 27 samples were positive for the NoV GI genogroup. Ten kinds of GI genotype (GI/1, GI/2, GI/3, GI/4, GI/5, GI/6, GI/7, GI/9, GI/12, and GI/13) and eight kinds of GII genotype (GII/2, GII/3, GII/4, GII/8, GII/14, GII/15, GII/16, and GII/17) were identified in children with AGE during the years 2008-2011.

Acute viral gastroenteritis is one of the most common infectious diseases in infants and young children. Rotavirus is mainly important in childhood. The present study determined the detection rate, seasonality and G and P genotypes of rotaviruses in children hospitalized for acute gastroenteritis in Seoul, Korea in 2009. A total of 1,423 stool specimens were screened by ELISA for the presence of rotavirus antigens and the rotavirus-positive stools genotyped by RT-PCR. The G genotype was determined for 90% of samples (242/269) and the P genotype for 93.3% (251/269). During the study, 25 G-P combinations were detected with G1P[8] in 38.3% (n = 103) and G4P[6] in 5.9% (n = 16) cases. These data provided information on rotavirus in patients with acute gastroenteritis in Seoul, Korea and provided baseline data to motivate for the implementation of control measures for rotavirus disease. Key words gastroenteritis, G and P types, rotavirus.Rotaviruses are recognized as the major etiological agents among infants and young children, and are the leading cause of life-threatening diarrhoeal disease in many countries (1,2,3). The virus is a member of the family Reoviridae and its genome is composed of 11 segments of double-stranded RNA that encode for the six structural proteins that make up the virus particles (viral proteins [VPs]) and six nonstructural proteins (NSPs) (3). The outer capsid is composed of two proteins, glycoprotein VP7 and protease-sensitive VP4 that confer protective immunity (4). Thus, VP7 and VP4 are used to classify RoVs (3). Semi-nested PCR, based on type-specific primers, is used to determine G and P genotypes. As VP7 and VP4 genes can and do segregate independently, a dual typing system is necessary in order to characterize the strains of RoVs co-circulating during different seasons in different locations (4). It is generally accepted that at least 23 G types [4] and 32 P types (5) are known. Among them, G1-4 are common human genotypes, though increase in prevalence of G12 and G9 strains have been reported worldwide (6). Epidemiological studies have shown that four G (G1-G4) and three P (P[4], P [6], and P[8]) are the most frequent VP7 and VP4 types (7). The distribution of different G and P genotypes and RoV strains varies from country and area to area and, therefore, knowledge of the molecular epidemiology of RoVs in circulation is important in the effort to develop a suitable and efficacious vaccine (7). The aims of this study were to investigate the detection rate of RoV infections and the prevalence of the G and P genotypes of RoV strains detected in children hospitalized with acute gastroenteritis in Seoul, Korea in 2009.

Waterborne outbreaks of enteric viruses are a major public health concern. The present study has been carried out to assess the presence of enteric viruses responsible for human acute gastroenteritis (AGE) in groundwater intended for drinking and produce washing. In total, 62 samples from groundwater for drinking and produce washing collected from Dec 2007 to Dec 2008 in Seoul were tested for enteric viruses using conventional RT-PCR, ELISA, and real-time RT-PCR. Our results showed that enteric viruses were detected in 7 (8.8%) groundwater samples. Rotaviruses were detected in 3 (4.8%) of the samples by ELISA; human adenoviruses were detected in 2 (3.2%) of the samples by ELISA; and nested RT-PCR detected noroviruses in 2 (3.2%) of the samples. In one of the groundwater sample, the norovirus RNA was detected by conventional RT-PCR which was confirmed positive by real-time RT-PCR. Additionally, real-time RT-PCR successfully detected norovirus RNA in five out of 62 water samples (8.1%). The data demonstrate that real-time RT-PCR will be useful as a rapid and sensitive method for detecting norovirus in water samples. Phylogenetic analysis revealed that the noroviruses detected in two of the groundwater samples belonged to GII-4. These studies can provide important information for the prevalence of enteric viruses in Korean groundwater.

The prevalence of human astroviruses was tested in patients with acute gastroenteritis by using conventional duplex reverse transcription (RT)-PCR and electrophoresis. Diarrheal fecal samples were collected from 9,597 patients at local hospitals in Seoul. The prevalence of astroviruses was 1.0% (94/9,597 patients; mostly infants), and that of sapoviruses was 0.1% (14/9,597 patients). Age- and gender-wise analyses were carried out on 29 astrovirus-positive patients having complete information on file regarding their age, gender, and other particulars. The results were higher in patients of ages 0 to 14 yr, and 69.0% of the astrovirus-positive patients were females, of which 69.2% were infants (0 to 12 months), and 61.5% were 1-4 yr old. Notably, in the case of 5 to 78-yr-old acute gastroenteritis patients, 100% were females.

Objectives: For our survey of the incidence of norovirus infections and the genogroup distribution of norovirus in Seoul, Republic of Korea, we evaluated through regular surveillance the prevalence of norovirus infections in patients with acute gastroenteritis occurring in Seoul from January 2007 to July 2011.Methods: For norovirus detection, we conducted epidemiological analyses on the basis of the junction of ORF1 and ORF2 (approximately 314 bp). 11,202 fecal specimens were collected from patients in Seoul with acute gastroenteritis between January 2007 and July 2011 and then tested for the presence of NoV via reverse transcription (RT) -polymerase chain reaction (PCR).Results: 16.6% (1,861/11,202) of the fecal specimens were determined to be positive for noroviruses. The incidences of norovirus infection in Seoul in the case of acute gastroenteritis with regular surveillance were 28. 0% in 2007, 14.6% in 2008, 9.1% in 2009, 14.1% in 2010, and 12.9% in 2011, which shows that noroviruses constituted a major causative agent of acute gastroenteritis. Also, the incidence of noroviral infection in patients with acute gastroenteritis increased after the large-scale new influenza in 2009. Conclusions:The genetic characteristics of norovirus and the epidemiologic patterns of a viral pathogen in acute gastroenteritis patients may provide potentially effective data for epidemiological studies in Seoul, Korea.