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Diarrhea is a common cause of morbidity and mortality among children younger than 5 years in developing countries. Children from 3 to 60 months of age were recruited from two hospitals in Nepal- Bharatpur Hospital, Bharatpur, and Kanti Children's Hospital, Kathmandu-in 2006 to 2009. Stool specimens collected from 1,200 children with acute diarrhea (cases) and 1,200 children without diarrhea (control subjects) were examined for a broad range of enteropathogens by standard microbiology, including microscopy, enzyme immunoassay for viral pathogens (adenovirus, astrovirus, and rotavirus) and protozoa (Giardia, Cryptosporidium, and Entamoeba histolytica), as well as by using reverse transcription real-time polymerase for norovirus. Antimicrobial susceptibility testing was performed using the disk diffusion method. Overall, rotavirus (22% versus 2%), norovirus (13% versus 7%), adenovirus (3% versus 0%), Shigella (6% versus 1%), enterotoxigenic Escherichia coli (8% versus 4%), Vibrio (7% versus 0%), and Aeromonas (9% versus 3%) were identified significantly more frequently in cases than control subjects. Campylobacter, Plesiomonas, Salmonella, and diarrheagenic E. coli (enteropathogenic, enteroinvasive, enteroaggregative) were identified in similar proportions in diarrheal and non-diarrheal stools. Campylobacter was resistant to second-generation quinolone drugs (ciprofloxacin and norfloxacin), whereas Vibrio and Shigella were resistant to nalidixic acid and trimethoprim/sulfamethoxazole. This study documents the important role of rotavirus and norovirus in acute diarrhea in children younger than 5 years, followed by the bacteria Shigella, enterotoxigenic E. coli, Vibrio cholera, and Aeromonas. Data on the prevalence and epidemiology of enteropathogens identify potential pathogens for public health interventions, whereas pathogen antibiotic resistance pattern data may provide guidance on choice of therapy in clinical settings.

Background: Norovirus is an important cause of childhood diarrhea. We present data from a longitudinal, multicountry study describing norovirus epidemiology during the first 2 years of life., Methods: A birth cohort of 1457 children across 8 countries contributed 7077 diarrheal stools for norovirus testing. A subset of 199 children contributed additional asymptomatic samples (2307) and diarrheal stools (770), which were used to derive incidence rates and evaluate evidence for acquired immunity., Results: Across sites, 89% of children experienced at least 1 norovirus infection before 24 months, and 22.7% of all diarrheal stools were norovirus positive. Severity of norovirus-positive diarrhea was comparable to other enteropathogens, with the exception of rotavirus. Incidence of genogroup II (GII) infection was higher than genogroup I and peaked at 6-11 months across sites. Undernutrition was a risk factor for symptomatic norovirus infection, with an increase in 1 standard deviation of length-for-age z score associated with a 17% reduction (odds ratio, 0.83 [95% confidence interval, .72-.97]; P = .011) in the odds of experiencing diarrhea when norovirus was present, after accounting for genogroup, rotavirus vaccine, and age. Evidence of acquired immunity was observed among GII infections only: Children with prior GII infection were found to have a 27% reduction in the hazard of subsequent infection (hazard ratio, 0.727; P = .010)., Conclusions: The high prevalence of norovirus across 8 sites in highly variable epidemiologic settings and demonstration of protective immunity for GII infections provide support for investment in vaccine development., (© The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America.)

This study identified norovirus in children presenting with acute gastroenteritis and determined the capsid genotypes of the circulating norovirus strains in multiple regions in Thailand during October 2004 to December 2006 and March 2008 to August 2010. A total of 7,420 stool samples were collected from both cases (3621) and controls (3799). The stool samples were screened by two real-time RT-PCR assays to detect genogroup I and genogroup II noroviruses. Norovirus-positive samples were identified in 516 cases (14.3%) and 181 controls (4.8%) with more than half of norovirus positive samples from 7-24 months old children. Positive samples were sequenced and genotyped for the capsid gene. GII.4 was the genotype observed most frequently (56.4%) followed by GII.3 (28.2%). Five peaks of infection were observed, with predominant capsid genotypes that alternated during the surveillance periods between GII.4 and GII.3. Analyses of positive samples showed variation in genotype from each region as well as from different study periods. This emphasizes the importance of multi-site studies to investigate norovirus epidemiology. Additionally, the observed regional and temporal variations suggest that a systematic nation-wide surveillance effort in Thailand is needed to track the continually changing norovirus epidemiology., (© 2015 Wiley Periodicals, Inc.)

Noroviruses (NoVs) are an important human pathogen associated with acute viral gastroenteritis worldwide. NoVs display a significant amount of genetic heterogeneity, making it difficult to develop comprehensive detection assays. In this study, primer sets and probes were designed for a TaqMan(®)-based real-time reverse transcription-polymerase chain reaction (RT-PCR) for norovirus detection purposes. The assay was optimized and utilized as a multiplex real-time RT-PCR assay for genogroup I (GI) detection, and a singleplex real-time RT-PCR assay for genogroup II (GII) detection. The assays showed high specificity for NoV detection and no cross-reactivity was observed between GI and GII. The detection limit of the assay was as low as 10 and 50 RNA copies per reaction for GI and GII, respectively. The optimized protocol was employed to assess the presence of NoV strains in clinical samples collected throughout Thailand during December 2005 to November 2006. The percentage of NoV infections among children with acute gastroenteritis (case) was 23.8% (119/500) and for children without acute gastroenteritis (control) it was 6.8% (30/441). The frequency of NoV infections varied geographically, with the highest frequency observed in the central region and the lowest frequency in the northern region (P>0.0001). Of the 149 positive case and control specimens, GII was found to be the predominant genogroup (98.6%). Partial capsid sequences were successfully obtained from 67 NoV-positive specimens and a phylogenetic analysis was performed to genotype the viral strains. GII.4 was the most common genotype detected., (Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.)

Noroviruses (NoV) and sapoviruses (SaV) are recognized as important causes of acute gastroenteritis in children worldwide. In this study, the prevalence and genetic variability of NoV and SaV were determined in hospitalized children <5 years of age with acute gastroenteritis in Hanoi, Vietnam. A total of 501 fecal specimens collected between November-2007 and October-2008, that previously had been tested for rotavirus (RV), were tested for NoV and SaV by realtime RT-PCR. Positive samples were genotyped by conventional RT-PCR followed by sequencing. GII NoV was detected in 180 (36%) and SaV in 7 (1.4%) of the samples. NoV was detected year-round ranging from 9.5% in April to 81.5% in September among RV negative samples. NoV GII.4 Minerva (2006b) was the dominant genotype (93%) with a few other genotypes detected including GII.3 (4.4%), GII.13 (1.7%), and GII.2 (0.6%) but no GI strains. Only GI and GII SaV strains were detected in this study. No difference in NoV prevalence between age groups was noted. Frequency of vomiting or fever was similar between children with NoV and RV infection, yet, NoV caused diarrhea with longer duration. In conclusion, NoV is the second most frequent cause of diarrhea in hospitalized children in North Vietnam., (Copyright © 2011 Wiley Periodicals, Inc.)