Viral etiology and incidence associated with acute gastroenteritis in a 5-year survey in Gyeonggi province, South Korea

Enteric and non-enteric adenoviruses associated with acute gastroenteritis in pediatric patients in Thailand, 2011 to 2017

Human adenovirus (HAdV) is known to be a common cause of diarrhea in children worldwide. Infection with adenovirus is responsible for 2–10% of diarrheic cases. To increase a better understanding of the prevalence and epidemiology of HAdV infection, a large scale and long-term study was needed. We implemented a multi-year molecular detection and characterization study of HAdV in association with acute gastroenteritis in Chiang Mai, Thailand from 2011 to 2017. Out of 2,312 patients, HAdV was detected in 165 cases (7.2%). The positive rate for HAdV infection was highest in children of 1 and 2 years of age compared to other age groups. HAdV subgroup C (40.6%) was the most prevalent, followed by subgroups F (28.5%), B (20.6%), A and D (4.8% each), and E (0.6%). Of these, HAdV-F41 (22.4%), HAdV-C2 (18.2%), HAdV-B3 (15.2%), and HAdV-C1 (13.3%) were the most common genotypes detected. HAdV infection occurred throughout the year with a higher detection rate between May and July. In conclusion, our study demonstrated the infection rate, seasonal distribution and genotype diversity of HAdV infection in children with diarrhea in Chiang Mai, Thailand over a period of 7 year. Not only enteric adenovirus (F40 and F41) but also non-enteric adenovirus (B3, C1, C2) may play an important role in gastroenteritis in this area. The information will be beneficial for the prevention and control of HAdV outbreaks in the future.

Detection and Molecular Characterization of Human Adenovirus Infections among Hospitalized Children with Acute Diarrhea in Shanghai, China, 2006-2011

Background: Human adenovirus (HAdV) is considered a significant enteropathogen associated with sporadic diarrhea in children. However, limited data are available regarding the epidemiology of HAdV in hospitalized children with viral diarrhea in Shanghai. The aim of this study was to characterize the epidemiology of HAdVs and describe their association with acute diarrhea in hospitalized children. Methods: A total of 674 fecal samples were subjected to PCR or RT-PCR to detect RVA, HuCV, HAstV, and HAdV. Results: HAdV infections were detected in 4.7% (32/674) of specimens, with detection rates of 13.4% (11/82), 4.6% (8/174), 3.2% (4/124), 4.1% (3/74), 2.0% (2/100), and 3.3% (4/120) from 2006 to 2011, respectively. Comprehensive detection of the four viruses revealed the presence of a high percentage (90.6%) of coinfections among HAdV-positive samples, where HAdV+RVA was the most prevalent coinfection. Of the 32 HAdV-positive samples, 50.0% (16/32) were classified as HAdV-41, and 18.8% (6/32) were classified as HAdV-3. Almost 94.0% of children infected with HAdV were less than 24 months of age. Conclusions: These results clearly indicated diversity across the HAdV genotypes detected in inpatient children with acute diarrhea in Shanghai and suggested that HAdVs play a role in children with acute diarrhea.

Molecular Epidemiology of Human Norovirus in Korea in 2013

Norovirus is a major cause of acute gastroenteritis. The molecular epidemiology of norovirus exhibits temporal and geographical fluctuations, and new variants of the GII.4 genotype emerge every 2-3 years to cause global epidemics of acute gastroenteritis. We investigated GI and GII genotypes of human norovirus strains isolated from patients with acute gastroenteritis in Korea in 2013. Norovirus antigen test was performed on 2,980 fecal specimens from January to December 2013. RNA was extracted from norovirus antigen-positive fecal suspensions, and the norovirus capsid (VP1) and polymerase (RdRp) genes were characterized by RT-PCR and sequencing. Of the 230 genotyped strains, GII.4 (77.3%) was the most frequently observed capsid genotype, followed by GII.3 (6.1%) and GII.13 (3.9%). A norovirus GII.4 variant, GII.Pe/GII.4 Sydney 2012, was the most frequently found polymerase/capsid genotype (65.7%), followed by GII.P17/GII.17 (2.1%) and GII.P21/GII.3 (2.1%). Phylogenetic, similarity, and capsid epitope analyses of GII.Pe/GII.4 Sydney 2012 strains were performed. We concluded that the norovirus GII.4 variant, GII.Pe/GII.4 Sydney 2012, was the main cause of norovirus-related gastroenteritis in Korea in 2013.

Molecular epidemiology of norovirus in South Korea

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.

Evolutionary phylodynamics of Korean noroviruses reveals a novel GII.2/GII.10 recombination event

Viral gastroenteritis is the most common causal agent of public health problems worldwide. Noroviruses cause nonbacterial acute gastroenteritis in humans of all ages. In this study, we investigated the occurrence of norovirus infection in children with acute gastroenteritis admitted to university hospitals in South Korea. We also analyzed the genetic diversity of the viruses and identified novel recombination events among the identified viral strains. Of 502 children with acute gastroenteritis admitted to our three hospitals between January 2011 and March 2012, genotyping of human noroviruses was performed in 171 (34%) norovirus-positive samples. Of these samples, 170 (99.5%) were in genogroup II (GII), while only one (0.5%) was in genogroup I (GI). The most common GII strain was the GII.4-2006b variant (n = 96, 56.5%), followed by GII.6 (n = 23, 13.5%), GII.12 (n = 22, 12.9%), GII.3 (n = 20, 11.8%), GII.2 (n = 6, 3.5%), GII.b (n = 2, 1.2%), and GII.10 (n = 1, 0.6%). Potential recombination events (polymerase/capsid) were detected in 39 GII strains (22.9%), and the most frequent genotypes were GII.4/GII.12 (n = 12, 30.8%), GII.4/GII.6 (n = 12, 30.8%), GII.4/GII.3 (n = 8, 20.5%), GII.b/GII.3 (n = 3, 7.7%), GII.16/GII.2 (n = 2, 5.1%), GII.4/GII.2 (n = 1, 2.6%), and GII.2/GII.10 (n = 1, 2.6%). For the first time, a novel GII.2/GII.10 recombination was detected; we also identified the GII.16/GII.2 strain for the first time in South Korea. Our data provided important insights into new recombination events, which may prove valuable for predicting the emergence of circulating norovirus strains with global epidemic potential.

A systematic review of genetic diversity of human rotavirus circulating in South Korea

Rotavirus infections continue to be the leading cause of severe diarrhea in young Korean children. Rotavirus data acquired from uninterrupted surveillance studies between 1989 and 2009 in South Korea were analyzed to better understand the genetic diversity and evolution. The relationship between rotaviruses and the currently licensed rotavirus vaccine viruses was also examined. The most prevalent rotavirus strains, with genotype G1P[8], followed by G3P[8], G4P[6], and G2P[4], accounted for approximately 76.7% of the total identified strains, and more recently, rotavirus G9P[8] has significance increased to be the fifth most common genotype. Phylogenetic analyses underscored the heterogeneity between viral populations within each genotype, with different lineages and sub-lineages. Although the currently licensed rotavirus vaccines are effective, safe, and economical, additional data from rotavirus monitoring is necessary to evaluate the efficacy of these vaccines for their sustained use in South Korea. The present study provides comprehensive and up-to-date information regarding the epidemiology, genetic diversity, and evolution of the circulating rotaviruses in South Korea.

Molecular epidemiology of norovirus GII.4 variants in children under 5 years with sporadic acute gastroenteritis in South Korea during 2006-2013

BACKGROUND

The global emergence of norovirus (NoV) GII.4 variants has raised public concerns in the world including South Korea since 1996.

OBJECTIVE

We analyzed seasonality and genotypic pattern for sporadic cases by norovirus GII-4 variants.

STUDY DESIGN

To determine the epidemic status of GII.4 variants in South Korea during 2006-2013, 7301 fecal specimens were collected from children who were younger than 5 years and had sporadic acute gastroenteritis (AGE).

RESULTS

During the study period, NoVs were the most prevalent viral agent, detected in 877 (12.0%) of the 7301 fecal specimens from children with sporadic AGE. NoV GII strains predominantly accounted for 97.6% of all sporadic NoV infections. NoV GII.4 was the most prevalent genotype and comprised 67.6% of the NoV GII strains. However, seasonal prevalence of GII.4 strains varied depending on the spread of GII.4 variants. GII.4-2006b variant most predominantly circulated from 2006-2007 to 2009-2010 and persisted during other seasons. GII.4-2009 variant was first detected in January 2010 and predominant in 2011-2012. However, it was rapidly displaced by GII.4-2012 variant, which emerged in May 2012 and substantially circulated in 2012-2013.

CONCLUSIONS

The frequent emergence and rapid spread of GII.4 variants significantly affect the magnitude of sporadic NoV infections in children. Hence, to minimize the disease burden of NoV infections, GII.4 strains should be considered as a primary target for vaccine development against NoVs.

Evaluation of an immunochromatographic assay for the rapid and simultaneous detection of rotavirus and adenovirus in stool samples

Background

We evaluated the analytical and clinical performances of the SD BIOLINE Rota/Adeno Rapid kit (SD Rota/Adeno Rapid; Standard Diagnostics, Inc., Korea), an immunochromatographic assay (ICA), for the simultaneous detection of rotaviruses and adenoviruses in human stool samples.

Methods

We tested 400 clinical stool samples from patients with acute gastroenteritis and compared the ICA results with the results obtained by using ELISA, enzyme-linked fluorescent assays (ELFA), PCR, and multiplex reverse transcription-PCR (mRT-PCR). To assess the analytical performance of the SD BIOLINE Rota/Adeno Rapid kit, we determined its detection limit, reproducibility, cross-reactivity, and analytical reactivity for adenovirus subtypes, and performed interference studies.

Results

The overall agreement rates among the tested methods were 91.5% for rotavirus and 85.5% for adenovirus. On the basis of mRT-PCR, the overall agreement, positive agreement, and negative agreement rates of the ICA were 95.6%, 100%, and 94.9% for rotavirus, and 94.0%, 71.4%, and 94.8% for adenovirus, respectively. Using the ICA, we detected all the subtypes of adenovirus tested, but the analytical reactivities for adenovirus subtypes were different between the 4 adenovirus detection methods. The high reproducibility was confirmed, and no cross-reactivity or interference was detected.

Conclusions

The SD BIOLINE Rota/Adeno Rapid kit showed acceptable analytical and clinical performances. However, interpretation of adenovirus positive/negative result should be cautious because of different detectability for adenovirus subtypes among adenovirus detection methods.

A retrospective analysis of acute gastroenteritis agents in children admitted to a university hospital pediatric emergency unit

BACKGROUND

Acute gastroenteritis is responsible observed in all age groups, especially infants and children. The etiology and clinical course of acute gastroenteritis may vary with age and etiological agents. In developing countries, the morbidity and mortality associated with infectious diarrhea is higher in children younger than five-years-of-age.

OBJECTIVES

The aim of this study was to determine the prevalence and seasonal distribution of the major agents of acute gastroenteritis in children who were admitted to a Turkish university hospital pediatric emergency unit during 2009.

PATIENTS AND METHODS

Seasonal distribution within a one year period and quantitative distribution were analyzed with demographic data and laboratory findings. A total of 644 subjects were enrolled in the study, with a mean age of 4.14 years. Pathogens were detected in 183 (28.4%) stool samples in children less than 16 years, admitted with acute gastroenteritis.

RESULTS

Pathogens were detected in 184 (28.4%) stool samples. The age distributions of the cases were 0 - 24 months (n = 59), 2 - 5 years (n = 100), and > 5 years (n = 25). The detection rate of rotavirus, norovirus and adenovirus were; 12.7% (75/588), 9.8% (51/520) and 4.9% (28/575), respectively. Bacterial agents were detected in 36 cases. The main agent was norovirus in the 0 - 24 months group (n = 25, 42.4%), and rotavirus for ages 2 - 5 years (n = 43, 43%) and > 5 years. On the monthly distribution, cases of rotavirus were found to be more frequent in the first four months of the year.

DISCUSSION

Viruses were the major pathogens in all age groups. Norovirus was the leading pathogen in the first two years. For the age groups 2 - 5 years and 6 - 16 years, rotavirus was the major pathogen.

Prevalence of rotavirus genotypes in South Korea in 1989-2009: implications for a nationwide rotavirus vaccine program

The epidemiology of human group A rotavirus was analyzed by examining genotypic data acquired from 1989 to 2009 in South Korea. This information was derived from all the available published articles on rotavirus studies in South Korea, retrieved from both the PubMed and KoreaMed databases. Four common G types (G1, G2, G3, and G4) and three common P types (P[8], P[4], and P[6]) accounted for approximately 93% and 99% of the rotavirus reports, respectively. The G9 type was frequently detected after 2000, and because of this prevalence, it is considered to be the fifth most important G type rotavirus after the G1.G4 genotypes. Less common G types of the virus such as G12, G11, and G10 were detected in some geographic settings, and it is important to consider the context of these subtypes and their epidemiological significance. The P[9] virus genotype was observed in the study and has been discussed in many other studies; however, the P[3], P[10] and P[25] genotypes were rarely detected in the epidemiological research. In general, the distributions of the G and P genotypes showed temporal and geographical fluctuations, and a nationwide rotavirus vaccine program that targeted these genotypes demonstrated effectiveness in protecting against the circulating rotavirus strains. However, further analysis is needed to determine the true long-term effectiveness of these vaccines; the analysis should also consider the unexpected effects of vaccinations, such as vaccine-induced diseases, herd immunity, and changes in host susceptibilities.

Etiological study of enteric viruses and the genetic diversity of norovirus, sapovirus, adenovirus, and astrovirus in children with diarrhea in Chongqing, China

BACKGROUND

Enteric viruses are a major cause of diarrhea in children, especially those <5 years old. Identifying the viral agents is critical to the development of effective preventive measures. This study aimed to determine the prevalence of common enteric viruses in children <5 years old presented with diarrhea to the Children's Hospital of Chongqing Medical University.

METHODS

Five hundred fecal samples were collected between August and November 2010 from children <5 years of age who presented with acute diarrhea at the Children's Hospital of Chongqing Medical University. All samples were tested for rotaviruses A, B, and C, noroviruses GI and GII, adenovirus, sapovirus, and astrovirus using enzyme-linked immunosorbent assay, reverse transcription-polymerase chain reaction (RT-PCR), or PCR. Partial sequences of norovirus, sapovirus, adenovirus, and astrovirus were phylogenetically analyzed to determine the genotype.

RESULTS

Enteric viruses were detected in 302 of the 500 children who presented with acute diarrhea (277/477; 58.07%) and persistent diarrhea (5/23; 21.74%). In 277 samples from children with acute diarrhea in whom at least one viral agent was found, rotavirus A was the most frequent virus identified (132 cases; 27.67%), followed by norovirus GII in 130 cases (27.25%), adenovirus in 30 cases (6.29%), sapovirus in 9 cases (1.89%) and astrovirus in one case (0.21%). Twenty-two of the norovirus GII-positive cases were randomly selected for genotyping. GII/4 was the predominant strain, followed by GII/6, GII/2, GII/3, and GII/7. Sapovirus was classified into four genotypes: GI/1 was predominant, followed by GI/2, GII/1, and GIV. The predominant adenovirus was type 41. Mixed infections were found in 25 cases, all of which presented with acute diarrhea (25/477; 5.24%). Viruses were positive in 5/23 (21.74%) cases with persistent diarrhea. Neither rotavirus B, rotavirus C, nor norovirus GI were found in any of the samples.

CONCLUSIONS

Enteric viruses are a major cause of diarrhea in children <5 years old in Chongqing. Rotavirus A is the most common etiological agent, follow by norovirus.

Frequency of rotavirus and adenovirus gastroenteritis among children in shiraz, iran

Background

Viral pathogens are the main cause of acute gastroenteritis in developed and developing countries. Rotavirus and adenovirus are the two important agents associated with hospitalization for diarrhea especially in children. Limitation and control of diarrhea as a costly disease must be considered in national health programs.

Objectives

Epidemiological studies on viral diarrhea and collecting data for rotavirus and adenovirus prevalence, as two important viral agents of gastroenteritis, are valuable for planning of a prospective program.

Materials and Methods

827 stool samples of pediatrics patients with gastroenteritis who were admitted to Dastgheib Hospital, Shiraz, Iran, from September 2008 to February 2010 were tested for presence of rotavirus and adenovirus using the EIA method. A demographic and clinical study was performed to determine the relationship between viral infection and clinical outcomes of patients.

Results

Rotavirus was identified in 347 patients out of 827 (42%), adenovirus was detected in 76 (9%) of samples and 34 (4%) of patients had rotavirus-adenovirus co-infection. Diarrhea was the most common symptom in viral infected patients.

Conclusions

Given the non-specific symptoms of these viruses and the high prevalence of viral diarrhea in our region, more laboratories should be equipped for virus detection and vaccination might be considered as a prevention strategy.

Norovirus contamination levels in ground water treatment systems used for food-catering facilities in South Korea

This study aimed to inspect norovirus contamination of groundwater treatment systems used in food-catering facilities located in South Korea. A nationwide study was performed in 2010. Water samples were collected and, for the analysis of water quality, the temperature, pH, turbidity, and residual chlorine content were assessed. To detect norovirus genotypes GI and GII, RT-PCR and semi-nested PCR were performed with specific NV-GI and NV-GII primer sets, respectively. The PCR products amplified from the detected strains were then subjected to sequence analyses. Of 1,090 samples collected in 2010, seven (0.64%) were found to be norovirus-positive. Specifically, one norovirus strain was identified to have the GI-6 genotype, and six GII strains had the GII, GII-3, GII-4, and GII-17 genotypes. The very low detection rate of norovirus most likely reflects the preventative measures used. However, this virus can spread rapidly from person to person in crowded, enclosed places such as the schools investigated in this study. To promote better public health and sanitary conditions, it is necessary to periodically monitor noroviruses that frequently cause epidemic food poisoning in South Korea.

Molecular characterization of human adenovirus infection in Thailand, 2009-2012

Background

Human adenovirus (HAdV) can cause a wide spectrum of human diseases worldwide.

Methods

Using PCR and sequence analysis, we investigated HAdV infection prevalence in the Thai population for four years from January 2009 to December 2012. We collected Nasopharyngeal swab/aspirate (NP) specimens from patients in Bangkok, Khon Kaen, and Nakhon Si Thammarat province and fecal specimens only from Bangkok and Khon Kaen province.

Results

We observed HAdV infection in 1.04% (82/7,921) of NP samples and in 5.84% (76/1,301) of fecal specimens. HAdV-B3 (32%) and HAdV-C1 (31%) were the genotypes most commonly associated with NP specimens followed by HAdV-C2 (13%) and HAdV-C5 (12%). In fecal specimens, we found that 25% harbored HAdV-F41 followed by HAdV-C1 (18%), HAdV-C2 (16%), and HAdV-B3 (13%). Out of all population subsets, children below the age of 3 years were the most likely to be HAdV positive (63.29%). In addition, HAdV infection occurred throughout the year without a seasonal distribution pattern, although HAdV infection of NP samples peaked from January-April while HAdV infection peaked from January to March and then again from May to July in fecal samples.

Conclusions

This study has for the first time reported the HAdV infection rate in Thai NP and fecal specimens from 2009–2012. We observed that HAdV-B3 and HAdV-C1 were commonly found in NP specimens, and that HAdV-F41 was the most prevalence in fecal specimens in Thailand during the study period.

Global seasonality of rotavirus disease

BACKGROUND

A substantial number of surveillance studies have documented rotavirus prevalence among children admitted for dehydrating diarrhea. We sought to establish global seasonal patterns of rotavirus disease before the introduction of widespread vaccination.

METHODS

We reviewed studies of rotavirus detection in children with diarrhea published since 1995. We assessed potential relationships between seasonal prevalence and locality by plotting the average monthly proportion of diarrhea cases positive for rotavirus according to geography, country development and latitude. We used linear regression to identify variables that were potentially associated with the seasonal intensity of rotavirus.

RESULTS

Among a total of 99 studies representing all 6 geographic regions of the world, patterns of year-round disease were more evident in low- and low-middle income countries compared with upper-middle and high-income countries where disease was more likely to be seasonal. The level of country development was a stronger predictor of strength of seasonality (P = 0.001) than geographic location or climate. However, the observation of distinctly different seasonal patterns of rotavirus disease in some countries with similar geographic location, climate and level of development indicate that a single unifying explanation for variation in seasonality of rotavirus disease is unlikely.

CONCLUSION

While no unifying explanation emerged for varying rotavirus seasonality globally, the country income level was somewhat more predictive of the likelihood of having seasonal disease than other factors. Future evaluation of the effect of rotavirus vaccination on seasonal patterns of disease in different settings may help understand factors that drive the global seasonality of rotavirus disease.

Detection and molecular characterization of adenoviruses in Korean children hospitalized with acute gastroenteritis

Human adenoviruses (HAdVs) are an important cause of acute gastroenteritis in children. However, few studies on the epidemiology or types of HAdVs associated with acute gastroenteritis have been conducted in Korea. Therefore, in the present study, the incidence of HAdV in 2064 stool samples from Korean children hospitalized with acute gastroenteritis (2004-2006) was assessed and the types of viruses present determined. Polymerase chain reaction, sequencing, and phylogenic analyses revealed that 113 samples (5.5%) were HAdV-positive. While HAdVs were mainly detected during July to October, no seasonal difference between the enteric and non-enteric viruses in the incidence of HAdV was observed. HAdV-41 and HAdV-40 were found in 54 (47.8%) and 3 (2.6%) HAdV-positive samples, respectively. HAdV-3, HAdV-7, HAdV-2, HAdV-31, HAdV-4, and HAdV-37 were detected in 11 (9.7%), 5 (4.4%), 2 (1.7%), 2 (1.7%), 1 (0.8%), and 1 (0.8%) of sample(s), respectively. Thus, not only enteric, but also non-enteric, HAdVs may play an important role in acute gastroenteritis in Korean children.

Complete genomic sequence analysis of norovirus isolated from South Korea

The complete nucleotide and deduced amino acid sequences of the RNA genome of a recently isolated norovirus (NoV) from Korea, designated Hu/GII-4/CBNU2/2007/KR (CBNU2), were determined and characterized by phylogenetic comparison with several genetically diverse NoV sequences. The RNA genome of CBNU2 is 7,560 nucleotides in length, excluding the 3' poly (A) tract. It includes three open reading frames (ORFs): ORF1, which encodes the nonstructural polyprotein (5-5,104); ORF2, which encodes VP1 (5,085-6,707); and ORF3, which encodes VP2 (6,707-7,513). ORF2-based phylogenetic analysis revealed that CBNU2 belonged to the GII.4 genotype, the most prevalent genotype, and formed a cluster with NoVs isolated from Asian regions, between 2006 and 2008. Comparative analysis with the consensus sequence of 207 completely sequenced NoV genomes showed 47 mismatched nucleotides: 26 in ORF1, 14 in ORF2, and 7 in ORF3, resulting in 8 amino acid changes: 3 in ORF1, 2 in ORF2, and 3 in ORF3. Phylogenetic analysis with full genome ORF1, ORF2, and ORF3 nucleotide sequences obtained from CBNU2 and each of the other representative NoV genomes suggested that CBNU2 had not undergone recombination with any of the other NoVs. A SimPlot analysis further supported this finding.

Genotypes of rotavirus associated with acute gastroenteritis in Seoul, Korea

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.

Frequency and phylogeny of norovirus in diarrheic children in Istanbul, Turkey

BACKGROUND

Norovirus (NoV) is recognised as one of the most common causes of foodborne infections. Contaminated shellfish, food, water and hospitals are well documented sources of the virus.

OBJECTIVE

NoV in diarrheic children has not previously been investigated in Istanbul, Turkey, hence the aim of this study was to detect and investigate the frequency and phylogeny of human NoV genogroups I and II in children with acute gastroenteritis.

STUDY DESIGN

238 stool samples were collected from diarrheic children from 2 hospitals (Cerrahpasa Medical School and Haseki) in Istanbul and analysed by ELISA, RT-PCR and real-time RT-PCR using both SYBR Green and probe-based assays for human NoV. Primers targeting the RNA-polymerase gene were used for RT-PCR to allow DNA sequencing of Turkish NoV strains and phylogenetic analysis to be performed.

RESULTS

NoV GII was detected in 36 (15.1%) of 238 samples by SYBR Green real-time RT-PCR, 10.9% by a probe-based real-time RT-PCR and 10.5% by ELISA (Ridascreen). Genogroup II (GII) the Turkish NoVs clustered with including GII4 (72.2%), GII16 (5.5%), GIIb (16.7%) and GIIe (5.5%). Two variants of GII4 (GII4-2006b and GII4-2008), GII16 and recombinant noroviruses (GIIb and GIIe) were identified.

CONCLUSION

This study shows a high frequency and genetic diversity of NoV GII infections in children with acute gastroenteritis in Istanbul, Turkey.

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.

Emergence of norovirus GII-4/2008 variant and recombinant strains in Seoul, Korea

Recently, the emergence of a new NoV GII-4 variant strain every 2 or 3 years has been reported. One hundred seventeen NoV GII strains were detected by RT-PCR in children with AGE between August 2008 and February 2010. In phylogenetic analyses, GII-4 and GII-3 were the most frequently detected strains. The detection rate of the 2008 variant was similar to that of the 2006b variant in the winter seasons of 2009 and 2010. This study shows a changing pattern of a predominant GII-4/2006b variant to the 2008 variant, as well as a novel NoV recombinant strain, GII-6/GII-14, in Korea.

Seasonal prevalence of asymptomatic norovirus infection in Korean children

The prevalence of asymptomatic norovirus (NoV) infection was investigated in children registered for kindergarten in Korea during the winter and summer. Children with no gastrointestinal symptoms, including diarrhea and abdominal pain, during the 2 weeks before and following sample collection were included in this investigation. NoV presence and genetic identification were determined with real-time reverse transcriptase-polymerase chain reaction and conventional nested reverse transcriptase-polymerase chain reaction. The prevalence of NoV in asymptomatic children was 5.5% in the winter and 3.5% in the summer, respectively. GII.4 was the most prevalent NoV genotype, but GII.2 and GI.10 were also found during genetic analysis. This study demonstrates that asymptomatic NoV infection may be an important source of transmission in kindergarten children.

Genetic analysis of norovirus GII.4 variants circulating in Korea in 2008

Noroviruses are the enteric pathogens most commonly responsible for infectious gastroenteritis and outbreaks of foodborne illness. The GII.4 norovirus, in particular, is responsible for the majority of epidemics. Here, we present data on the distribution of norovirus genotypes in Chungnam, Korea, in 2008, measure genetic variation among GII.4 strains, and compare Korean GII.4 variants with reference strains based on the 237-bp junction of ORF1 and ORF2. We detected 139 different strains, which formed two distinct genetic clusters with significant sequence diversity. One Korean cluster (2008-Korea_a) showed high similarity to the Sakai cluster that appeared in Japan and Europe in 2006. The other cluster (2008-Korea_b) was unique and unrelated to previously reported clusters. Genotype GII.4 was confirmed as the predominant cause of norovirus epidemics in Korea. Foodborne norovirus infections, on the other hand, were generally caused by emerging GII.4 genetic variants similar to those responsible for global epidemics.

Rotavirus and adenovirus frequency among patients with acute gastroenteritis and their relationship to clinical parameters: a retrospective study in Turkey

BACKGROUND

Diarrhea is the third leading cause of death related to infectious diseases all over the world. The diseases related to viral gastroenteritis are gradually increasing, particularly in the developed countries. The purpose of our study was to determine the frequency and to investigate the clinical manifestations of acute rotavirus and adenovirus gatroenteritis and to assess the diagnostic value of the related clinical findings.

METHODS

In 2007-2008 patients with diarrhea and/or vomiting attended to Yeditepe University Hospital and related clinics, Istanbul, were studied. The rotavirus and/or adenovirus antigen in stool of these patients were investigated. Data regarding clinical findings were collected from the electronic records, retrospectively. Age, gender, symptoms, fever, antibiotic use, vomiting, number of vomiting and diarrhaeae, dehydration, abdominal pain, the other pathological physical examination findings were analyzed by the physicians in the study group. To investigate the rotavirus and adenovirus antigen CerTest Rota-Adeno Blister Test (CerTest, Biotec, Spain), a qualitative immunochromotographic assay was used. Statistical analysis wasperformed with SPSS v. 11,5 statistical software. X2 test was used for bivariate and logistic regression analysis was used for multivariate analysis.

RESULTS

Rotavirus positivity was 18,7% (n = 126). Concomitantly, in 596 cases adenovirus antigen test were also performed. Adenovirus positivity was 8,9% (n = 53) and rota-adenovirus co-infection was 4,4% (n = 26). Most of rotavirus positive cases were seen in December, January, February and March (p < 0.001). In clinical parameters, there was a significant difference between rotavirus positive cases and negative cases regarding to vomiting, dehydration and vomiting and diarrhea coexistence (respectively p = 0.010, p < 0.00, p = 0.007).

CONCLUSION

Rotavirus can be seen in all age groups, but more frequently in childhood. Although there is no clinical gold standard to distinguish the rotavirus cases from the other gastroenteritis agents, the findings of dehydration and vomiting-diarrhea coexistence, considering months of referral may lead clinician to perform rapid antigen tests and affect approach to the treatment. Prospective studies with representative samples are needed to determine the rotavirus and adenovirus incidence and to develop safe and reliable protective policies in our country.

A survey of intestinal protozoan infections among gastroenteritis patients during a 3-year period (2004-2006) in Gyeonggi-do (province), South Korea

The incidence and etiology of parasite-associated gastroenteritis during 2004-2006 in Gyeonggi-do (province), South Korea was determined by means of antigen detection ELISA on 6,071 stool specimens collected from 6 general hospitals. At least 1 parasitic agent was detected in 3.4% (208/6,071) of the stool samples. Among these, Giardia lamblia was the most numerous (152 cases; 2.5%), followed by Entamoeba histolytica (25 cases; 0.4%), Cryptosporidium parvum (23 cases; 0.4%), and mixed infections (8 cases; 0.1%). Patients aged 1-5 years had the largest proportion (69.2%; 144/208) of parasite-positive stool specimens. Parasite-mediated gastroenteritis was most common from June to September. The detection rate gradually increased from 2004 to 2006. This study shows that parasite-mediated gastroenteritis may be significant among children in Korea and that parasite infection surveillance should be constantly performed.