Diversity of viruses associated with acute gastroenteritis in children hospitalized with diarrhea in Ho Chi Minh City, Vietnam

Molecular epidemiology of norovirus gastroenteritis in children in Jiangmen, China, 2005-2007

Human noroviruses (NoVs) are an important cause of epidemic acute gastroenteritis. Their role in sporadic cases, however, is less clear. In this study, we performed a two-year surveillance (September 2005 to August 2007) of NoV gastroenteritis in outpatient clinics in a southern city of China, Jiangmen City. NoVs were detected in 115 patients (115/881, 13.1%) with 30 (26.1%) co-infections with rotaviruses. Sequence analysis showed that all 115 NoVs belonged to genogroup II, with GII.4 being the most predominant (87.8%). NoV-associated infection can be seen year-around, with autumn and winter peaks. This study provides basic information on sporadic cases of major NoV gastroenteritis in children in different seasons, which is valuable for future disease control and prevention.

First description of gastroenteritis viruses in Lebanese children: a pilot study

Human enteric viruses are important causes of acute gastroenteritis in infants and children. The role of rotaviruses, adenoviruses, human caliciviruses and astroviruses in the development of severe acute gastroenteritis requiring hospitalization of infants and young children in North Lebanon was investigated. Stool specimens collected between April and May 2010 from 79 Lebanese infants and children hospitalized for severe acute gastroenteritis, were screened for enteric viruses by immunoassays and internally controlled multiplex PCR assay. Out of 79 stool samples, 38 (48%) were positive for rotavirus, and 5 (6%) were positive for norovirus genogroup II. Enteric adenoviruses, sapoviruses and human astroviruses were not detected. Children with severe rotavirus gastroenteritis were younger than those with severe norovirus gastroenteritis. These results highlight the importance of rotavirus and norovirus as causes of severe gastroenteritis in Lebanese children, and the need to incorporate routine screening tests for norovirus infection in clinical settings.

[Epidemiological analysis of norovirus infection between March 2007 and February 2010]

BACKGROUND

Norovirus is a common cause of non-bacterial acute gastroenteritis worldwide, and norovirus infection shows symptoms such as vomiting and diarrhea in patients of all age groups. Mass outbreaks of norovirus infection have been recently reported in Korea. Herein, we investigated the epidemiological characteristics of acute norovirus gastroenteritis.

METHODS

We analyzed 11,219 fecal specimens of patients with acute gastroenteritis symptoms from the 5 participating hospitals for 3 yr (March 2007-February 2010) to determine positive rates of detection using RIDASCREEN Norovirus ELISA (R-Biopharm AG, Germany) kit by year, prevalence season, sex, age, and region.

RESULTS

Norovirus infection was prevalent during autumn and winter, and 13.0% specimens were positive for the infection. The positive rates of norovirus detection were 16.2%, 13.8%, and 9.9% in 2007, 2008, and 2009, respectively, and they tended to decrease every year. In 2007 and 2008, the epidemicity of norovirus started from October, reached its peak in November, and lasted until January. However, in 2009, it started from December, reached its peak in January, and lasted until February. Most patients were 0-3 yr old and this patient group had the highest positive rate. There was no significant inter-regional difference among the subjects.

CONCLUSIONS

We performed epidemiological analysis of norovirus infection using ELISA assay. Reverse transcription-PCR indicated higher prevalence of norovirus infection as compared with that reported before 2007. Further studies are warranted to examine the changes observed in the epidemic period of 2009.

Epidemiology and clinical features of gastroenteritis in hospitalised children: prospective survey during a 2-year period in a Parisian hospital, France

Rotavirus is recognised as the most important agent of severe acute gastroenteritis (AGE) in young children. In a 2-year prospective survey, we investigated the epidemiology and clinical features of the viral and bacterial pathogens in children hospitalised for AGE. The study was performed in a Parisian teaching hospital from November 2001 to May 2004. Clinical data were prospectively collected to assess the gastroenteritis severity (20-point Vesikari severity score, the need for intravenous rehydration, duration of hospitalisation). Stools were systematically tested for group A rotavirus, norovirus, astrovirus and adenovirus 40/41, sapovirus and Aichi virus and enteropathogenic bacteria. A total of 457 children (mean age 15.9 months) were enrolled. Viruses were detected in 305 cases (66.7%) and bacteria in 31 cases (6.8%). Rotaviruses were the most frequent pathogen (48.8%), followed by noroviruses (8.3%) and adenoviruses, astroviruses, Aichi viruses and sapoviruses in 3.5%, 1.5%, 0.9% and 0.4%, respectively. Cases of rotavirus gastroenteritis were significantly more severe than those of norovirus with respect to the Vesikari score, duration of hospitalisation and the need for intravenous rehydration. Rotaviruses were the most frequent and most severe cause in children hospitalised for AGE, and noroviruses also account for a large number of cases in this population.

Isolated norovirus GII.7 strain within an extended GII.4 outbreak

Noroviruses are a major cause of viral gastroenteritis and have been detected with increasing prevalence in recent years. Currently, two main genogroups GI and GII with an increasing number of subtypes are differentiated. Because of a high genetic variability new variants emerge constantly allowing epidemiological tracing of viruses from year to year and location to location. A 282 bp sequence at the 5'end of the capsid gene was analyzed in isolates originating from the University hospital, Technische Universität München. Phylogenetic analysis was based on 20 GII positive samples from an outbreak in March/April 2006 and 8 samples from the following winter season 2006-2008. In the initial outbreak two distinct genotypes were identified. The GII.4 strain 2006a found in the majority of outbreaks in 2006 worldwide was isolated from all but two patients. These two individuals were infected with a GII.7 strain clustering mainly with isolates from Asia. Of note, they excreted noroviral RNA for 81 and 27 days, respectively. Longitudinal analysis of an extended 1381 bp sequence revealed positive selection in the P2 domain. The variant was very similar to GII.7 strains isolated in 1990 and 1994 suggesting slow evolution with evidence of recombination according to the SimPlot analysis. Strains found in the following years 2006-2008 clustered around the isolate GII.4 2006b, characterized in the spring of 2006 and reaching a high prevalence in 2006-2007. The results provide an insight into norovirus evolution at a University hospital over 3 years and describe intraindividual evolution within a patient infected chronically.

Genetic and phenotypic characterization of GII-4 noroviruses that circulated during 1987 to 2008

The predominance and continual emergence of new variants in GII-4 noroviruses (NVs) in recent years have raised questions about the role of host immunity and histo-blood group antigens (HBGAs) in NV evolution. To address these questions, we performed a genetic and phenotypic characterization of GII-4 variants circulating in the past decade (1998 to 2008). Ninety-three GII-4 sequences were analyzed, and of them, 16 strains representing 6 genetic clusters were selected for further characterization. The HBGA binding properties were determined by both saliva- and oligosaccharide-binding assays using P particles as a model of NV capsid. The antigenic properties were also examined by enzyme immunoassay (EIA), Western blot analysis, and receptor blocking assay, using P-particle-specific antibodies from immunized mice and GII-4 virus-infected patients. Our results showed that 15 of the 16 GII-4 viruses bound to saliva of all A, B, and O secretors. Oligosaccharide binding assays yielded largely consistent results, although the binding affinities to some oligosaccharides varied among some strains. The only nonbinder had a mutation in the binding site. While antigenic variations were detected among the 16 strains, significant cross-blocking on the HBGA binding was also noted. Sequence alignment revealed high conservation of HBGA binding interfaces with some variations in adjacent regions. Taken together, our data suggested that the ability of GII-4 to recognize different secretor HBGAs persisted over the past decade, which may explain the predominance of GII-4 over other genotypes. Our data also indicated that both the host immunity and HBGAs play a role in NV evolution. While host immunity may continue driving NV for antigenic change, the functional selection by the HBGAs tends to lock the architecture of the capsid/HBGA interfaces and allows only limited variations outside the HBGA binding sites. A potential outcome of such counterselection between theses two factors in NV evolution is discussed.

Sequence analysis of the VP7 gene of human rotaviruses G2 and G4 isolated in Japan, China, Thailand, and Vietnam during 2001-2003

Sequence and phylogenetic analyses of the rotavirus VP7 gene were performed on 52 human G2 and G4 strains isolated in Japan, China, Thailand, and Vietnam during 2001-2003. All genotype G2 strains included in the study clustered into lineage II of the phylogenetic tree, together with the majority of global G2 strains detected since 1995. The amino acid substitution at position 96 from aspartic acid to asparagine was noted among the emerging or re-emerging G2 rotavirus strains in Japan, Thailand, and Vietnam during 2002-2003. Genotype G4 strains detected in Vietnam grouped into lineage Ia of the phylogenetic tree, whereas Japanese G4 strains clustered in lineage Ic which included emerging G4 strains from Argentina, Italy, Paraguay, and Uruguay. It is noteworthy that an insertion of asparagine was found at position 76 in all the Japanese strains and that its presence might be involved in the emergence of G4 rotavirus in Japan during 2002-2003.

Viruses causing childhood diarrhoea in the developing world

PURPOSE OF REVIEW

Acute gastroenteritis is one of the leading causes of morbidity and mortality in children in the developing world. With improvements in hygiene and sanitation, the burden of disease due to bacterial and parasitic infections has decreased and an increasing proportion of diarrhoea hospitalizations are attributed to viruses. This review focuses on enteric viruses and their role in childhood diarrhoea in the developing world.

RECENT FINDINGS

With the use of sensitive molecular techniques, it is evident that a significant proportion of childhood diarrhoea is attributable to enteric viruses, with at least one viral agent in nearly 43% of samples from childhood diarrhoea in developing countries. Rotaviruses remain the most common pathogens in children, followed by noroviruses in almost all countries. There is increasing evidence that both rotaviruses and caliciviruses spread beyond the gut in a large proportion of infections.

SUMMARY

The review highlights the importance of viral agents of gastroenteritis in developing countries. Wider use of molecular techniques is resulting in rapid identification of new or emerging strains and in the detection of extra-intestinal spread. There is a need to better understand susceptibility and immune response to these agents to be able to design suitable interventions.

Molecular epidemiology of human astrovirus and adenovirus serotypes 40/41 strains related to acute diarrhea in Tunisian children

Human astrovirus (AstV) and adenovirus types 40 and 41 (AdV 40/41) are responsible for epidemic and endemic acute gastroenteritis in children and adults. The present study was designed to evaluate the prevalence and genetic diversity of enteric viruses in children in Tunisia. A total of 788 fecal samples were collected during a 4-year period in the region of Monastir, from children under 12 years old, hospitalized or presenting in dispensaries with symptoms of acute gastroenteritis. AstV and AdV40/41 were detected by immunoenzymatic methods and confirmed by PCR/RT-PCR and sequence analysis. Phylogenetic analyses were performed for nucleotide homology with reference strains. AstV and AdV40/41 were characterized as a causative agent in 28 (3.6%) and 18 (2.3%) of the fecal samples, respectively. Phylogenetic analysis showed that the AstVs belonged to the serotypes 3 (n = 4; 14.3%) and 1 (n = 24; 85.7%), and the enteric AdVs to the serotypes 40 (n = 1; 5.6%) and 41 (n = 17; 94.4%). This is the first report that describes the molecular epidemiology of AstV and AdV40/41 in Tunisian children. Their respective detection rate was very low, far below that of rotavirus and norovirus. The genetic diversity among these two viruses is relatively limited and varies depending on the area.

Molecular epidemiology of norovirus infection among children with acute gastroenteritis in Shanghai, China, 2001-2005

Norovirus is one of the major causes of outbreaks and sporadic cases of acute gastroenteritis in young children worldwide. Obtaining local baseline information regarding this virus is important for developing and evaluating prevention strategies of norovirus transmission in children. The age, seasonal distribution and circulating genotypes of norovirus in Shanghai, China, between 2001 and 2005 were determined. Of 5411 stool specimens collected from children under 5 years of age who were hospitalized with acute gastroenteritis 3,975 were rotavirus-negative, indicating the presence of another causative agent. From these specimens, 484 were selected at random for genotyping, and 45 were norovirus-positive. Norovirus infection was detected in all age groups, but infants less than 6 months old showed the lowest prevalence (5.4%). Norovirus infections peaked from August to November. Among the 37 identified norovirus strains, 2 were GII-3, 2 were GII-7, and 33 were GII-4 genotypes. This study demonstrated the impact of norovirus infection causing acute gastroenteritis in hospitalized children and the importance of vaccination against norovirus diarrhea in Shanghai, China.

Norovirus highly prevalent cause of endemic acute diarrhea in children in the peruvian Amazon

To determine the burden of norovirus infections in children stools from a longitudinal community cohort were evaluated using reverse transcription polymerase chain reaction. Norovirus was detected in 21.3% of diarrheal and 8.0% of nondiarrheal stools (P < 0.01). Norovirus diarrhea was highly associated with age and the odds ratio for norovirus diarrhea fell by 2.8% per month (OR = 0.97, 95% CI: 0.95-0.99). Norovirus seems to be an important etiology of community acquired diarrhea in this study population.

Molecular characterization of rotaviruses, noroviruses, sapovirus, and adenoviruses in patients with acute gastroenteritis in Thailand

Outbreaks of viral gastroenteritis occur worldwide including Thailand. Unfortunately, there is limited information since etiologic agents have not been identified in several outbreaks of nonbacterial gastroenteritis. The genotype of enteric viruses causing acute gastroenteritis in Thailand was determined using reverse transcription-multiplex polymerase chain reaction and DNA sequencing. From January 2006 to February 2007, stool samples were collected from patients with acute gastroenteritis of all age groups attending a hospital in Thailand, and patients with nonbacterial acute gastroenteritis (262 patients) were tested for enteric viruses. The overall positive detection rate of enteric viruses was 14.9%; group A rotaviruses (6.1%), noroviruses (6.5%): GI (0.8%) and GII (5.7%), adenoviruses (1.5%), and sapoviruses (0.8%) were found. Group B and C rotaviruses, and astroviruses were not detected in the enrolled patients. Viral acute gastroenteritis occurred in children less than 15 years of age (25.2%, 33/131) with higher frequency than in adults (4.6%, 6/131), P-value <0.001. Rotavirus G1 was the most predominant genotype, followed by G3, and G9. Among noroviruses, GI-2 was identified; whereas, GII was predominant with a high frequency of GII-4 observed, followed by GII-16, GII-2, GII-3, and GII-12. Sapovirus GII-3 and human adenoviruses were identified. This study suggests that enteric viruses play an essential role in patients with acute gastroenteritis attending hospital and mainly in children who have a higher prevalence of group A rotaviruses and noroviruses. The genetic analyses provide molecular epidemiological data for viruses important to public health.

Viral agents associated with acute gastroenteritis in children hospitalized with diarrhea in Lanzhou, China

BACKGROUND

Gastroenteritis is a major cause of childhood morbidity and mortality worldwide. Rotavirus, human caliciviruses (HucV), adenovirus, and astrovirus are recognized as common etiologies of acute gastroenteritis.

OBJECTIVES

To use antigen detection and molecular methods to determine the viral etiology of childhood diarrhea in Lanzhou, China, 2005-2007.

STUDY DESIGN

544 stool specimens were collected from children hospitalized with diarrhea. ELISA, RT-PCR, or PCR were used to detect viruses commonly causing diarrhea.

RESULTS

Group A rotavirus, norovirus, sapovirus, astrovirus, and adenovirus, were detected in 54.0%, 9.2%, 1.1%, 3.3%, and 4.4%, respectively. No group B or group C rotaviruses were detected. The relative contribution of these viruses changed greatly over 2 years. The percentage of rotavirus and adenovirus dropped from 61.2% and 5.4% to 47.6% and 1.4%, whereas HucV increased from 5.0% to 15.0%. G1 and P[8] were the predominant rotavirus strains, and P[6] was detected for the first time in this area. The predominant norovirus strain changed from GII3 to GII4, and the subtypes of GII4 changed from the Hunter strain to the variant 2006b strain.

CONCLUSIONS

The distribution of viruses and genotypes of individual viruses causing gastroenteritis in Lanzhou, China changed greatly during 2005-2007.

Development of genotype-specific primers for differentiation of genotypes A and B of Aichi viruses

A nested polymerase chain reaction method using genotype-specific primers based on the capsid gene was developed to differentiate between genotypes A and B of Aichi viruses. Results of the study showed that the PCR using newly designed genotype-specific primers could generate appropriate PCR products from all 17 samples tested, the newly developed primers could differentiate genotype A from genotype B, and all matched those obtained by nucleotide sequencing of the capsid regions. The nested PCR method using genotype-specific primers is useful and can be used for genotyping of Aichi viruses isolated from epidemiological studies.

Human bocavirus in children hospitalized for acute gastroenteritis: a case-control study

Background. Human bocavirus (HBoV) was recently discovered in children with respiratory tract disease and gastroenteritis. The causative role of HBoV in human gastroenteritis remains uncertain, and, to our knowledge, no previous case-control study has studied the relationship between HBoV and gastroenteritis.

Methods. We conducted a case-control study that examined stool samples from 397 children with diarrhea and from 115 asymptomatic control subjects. HBoV was detected using polymerase chain reaction. Real-time polymerase chain reaction was used to quantify the HBoV loads in case and control groups. Common enteric viruses were examined using enzyme-linked immunosorbent assays, polymerase chain reaction, and reverse-transcription polymerase chain reaction.

Results. At least 1 viral agent was discovered in 60.2% of cases. HBoV was detected in 14 samples, and 9 were coinfected with either rotavirus (7 of 14 samples) or human calicivirus (2 of 14). Many (8 [57.1%] of 14) of the HBoV infections occurred during September-December 2006. Most (12 [85.7%]) of the HBoV-infected children were 7–18 months of age. The percentage of children with HBoV infection did not differ significantly between case patients and control subjects (3.5% vs. 3.5%), and the statistical analysis did not support a correlation between HBoV infection and more-severe clinical symptoms. The viral load differences between the 2 groups were not statistically significant (P = .09, by log-normal Student's t test). In addition, the VP1/VP2 partial gene of HBoV from case patients and control subjects showed minimal sequence variation.

Conclusions. A single genetic lineage of HBoV was revealed in persons in China. Despite its high prevalence in stool samples, our study does not support a causative role of HBoV in gastroenteritis.

Sequence analysis of the capsid gene of Aichi viruses detected from Japan, Bangladesh, Thailand, and Vietnam

Sequence analysis of the capsid gene of Aichi viruses was performed on 12 strains detected in Japan, Bangladesh, Thailand, and Vietnam during 2002-2005. The phylogenetic tree constructed from 17 nucleotide sequences of the capsid gene of the strains studied and reference strains demonstrated that Aichi virus strains clustered into two branches. A classification of Aichi viruses based on the capsid gene was proposed, in which lineage I consists of the Aichi virus strains detected from Japan, Thailand, Vietnam, and Germany, and lineage II includes Bangladeshi strains and a Brazilian strain.

Viral diversity and dynamics in an infant gut

Metagenomic sequencing of DNA viruses from the feces of a healthy week-old infant revealed a viral community with extremely low diversity. The identifiable sequences were dominated by phages, which likely influence the diversity and abundance of co-occurring microbes. The most abundant fecal viral sequences did not originate from breast milk or formula, suggesting a non-dietary initial source of viruses. Certain sequences were stable in the infant's gut over the first 3 months of life, but microarray experiments demonstrated that the overall viral community composition changed dramatically between 1 and 2 weeks of age.

Acute infantile gastroenteritis associated with human enteric viruses in Tunisia

This prospective study, conducted from January 2003 to June 2005, investigated the incidence and the clinical role of various enteric viruses responsible for infantile gastroenteritis in 632 Tunisian children presenting in dispensaries (380 children) or hospitalized (252 children) for acute diarrhea. At least one enteric virus was found in each of 276 samples (43.7%). A single pathogen was observed in 234 samples, and mixed infections were found in 42 samples. In terms of frequency, rotavirus and norovirus were detected in 22.5 and 17.4% of the samples, respectively, followed by astrovirus (4.1%), Aichi virus (3.5%), adenovirus types 40 and 41 (2.7%), and sapovirus (1.0%). The seasonal distribution of viral gastroenteritis showed a winter peak but also an unusual peak from May to September. The severity of the diarrhea was evaluated for hospitalized infants. No significant differences were observed between rotavirus and norovirus infections with regard to the incidence and the clinical severity of the disease, especially in dehydration.

Molecular epidemiology of norovirus infections in children with acute gastroenteritis in South Korea in November 2005 through November 2006

Norovirus infections were detected in 114 of 762 children with acute gastroenteritis in South Korea from November 2005 to November 2006. Seasonality peaks in December, March, and October were also assessed in this study. We identified seven noroviral genotypes (GI-6, GII-2, GII-3, GII-4, GII-5, GII-6, and GII-8) and a C1-120 strain showing low identity (79.3%) with GII-13 and GII-17.