High prevalence of noroviruses among hospitalized diarrheal patients in Bangladesh, 2011

Biological Specimen Banking as a Time Capsule to Explore the Temporal Dynamics of Norovirus Epidemiology

Norovirus is recognised as a major cause of epidemic and sporadic acute gastroenteritis (AGE) in all age groups. Information on the genetic diversity of the noroviruses circulating in the 1980s and 1990s, before the development and adoption of dedicated molecular assays, is limited compared with the last decades. Between 1986 and 2020, uninterrupted viral surveillance was conducted in symptomatic children hospitalized with AGE in Palermo, Italy, providing a unique time capsule for exploring the epidemiological and evolutionary dynamics of enteric viruses. A total of 8433 stool samples were tested using real-time RT-PCR. All samples were stored at -20 or -80 °C until processing. In this 35-year long time span, noroviruses of genogroup II (GII) were detected in 15.6% of AGE requiring hospitalization, whilst GI noroviruses were detected in 1.4% of AGE. Overall, the predominant norovirus capsid (Cap) genotype was GII.4 (60.8%), followed by GII.3 (13.3%) and GII.2 (12.4%). Temporal replacement of the GII.4 Cap variants associated with different polymerase (Pol) types were observed over the study period. The chronology of emergence and circulation of the different GII.4 variants were consistent with data available in the literature. Also, for GII.3 and GII.2 NoVs, the circulation of different lineages/strains, differing in either the Cap or Pol genes or in both, was observed. This long-term study revealed the ability of noroviruses to continuously and rapidly modify their genomic makeup and highlights the importance of surveillance activities in vaccine design.

Epidemiology and Risk Factors of Norovirus Infections Among Diarrhea Patients Admitted to Tertiary Care Hospitals in Bangladesh

BACKGROUND

Norovirus is a major cause of endemic acute gastroenteritis (AGE) worldwide. We described the epidemiology, risk factors, and genotypic distribution of noroviruses among hospitalized patients of all ages in Bangladesh.

METHODS

From March 2018 to October 2021, 1250 AGE case patients and controls (age, sex, season, and site matched) were enrolled at 10 hospitals. Demographic and clinical information was collected; real-time reverse-transcriptase polymerase chain reaction (RT-PCR) used to test stool specimens, and positive samples were genotyped.

RESULTS

Norovirus was detected in 9% of cases (111 of 1250) and 15% (182 of 1250) of controls. Eighty-two percent of norovirus-positive cases were in children <5 years old. Norovirus-positive AGE hospitalizations occurred year-round, with peaks in April and October. Risk factors for norovirus included age <5 years (adjusted odds ratio, 3.1 [95% confidence interval, 1.9-5.2]) and exposure to a patient with AGE in the 10 days before enrollment (3.8 [1.9-7.2]). GII.3[P16] and GII.4 Sydney[P16] were the predominant genotypes.

CONCLUSIONS

We highlight the burden of norovirus in hospital settings. Young age and recent exposure to a patient with AGE were risk factors for norovirus. A high prevalence of norovirus among controls might represent asymptomatic reinfections or prolonged shedding from a previous infection; carefully designed longitudinal studies are needed to improve our understanding of norovirus infections in Bangladesh.

Hepatitis E Virus; An Underestimated Threat for the Viral Hepatitis Elimination Program

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Hospital-based Surveillance for Pediatric Norovirus Gastroenteritis in Bangladesh, 2012-2016

BACKGROUND

Globally, noroviruses are recognized as an important cause of acute gastroenteritis (AGE), but data from low and middle-income countries are limited.

AIMS

To examine the epidemiology and strain diversity of norovirus infections among children hospitalized for AGE in Bangladesh.

METHODS

We implemented active surveillance of children <5 years of age hospitalized with AGE at 8 geographically dispersed tertiary care hospitals in Bangladesh from July 2012 to June 2016. We tested random samples of AGE cases stratified by site and age group for norovirus by real-time RT-PCR. Noro-positive specimens were genotyped. Coinfection with rotavirus was assessed based on prior EIA testing.

RESULTS

We enrolled 5622 total AGE cases, of which 1008 were tested for norovirus. Total of 137 (14%) AGE cases tested positive for norovirus (range, 11%-17% by site). Most (94%) norovirus-associated hospitalizations were among children less than 2 years of age. Norovirus was detected year-round, with higher detection from March to June (20%-38%) and November to January (9%-18%). Genogroup II (GII) noroviruses were detected in 96% of cases, and the most frequent genotypes were GII.4 Sydney [P4 New Orleans] (33%), GII.3 [P16] (20%), and GII.4 Sydney [P16] (11%). The proportion of norovirus-positive specimens was significantly greater among rotavirus-negative AGE patients compared with rotavirus-positive AGE patients (27% vs. 5%, P < 0.001). As measured by the Vesikari severity score, a similar proportion of norovirus and rotavirus positive AGE patients were considered severe (68% vs. 70%, P = 0.86).

CONCLUSIONS

Norovirus is an important cause of AGE hospitalization in Bangladeshi children with most infections caused by GII viruses.

Norovirus strains in patients with acute gastroenteritis in rural and low-income urban areas in northern Brazil

From 2010-2016, a total of 251 stool samples were screened for norovirus using next-generation sequencing (NGS) followed by phylogenetic analysis to investigate the genotypic diversity of noroviruses in rural and low-income urban areas in northern Brazil. Norovirus infection was detected in 19.9% (50/251) of the samples. Eight different genotypes were identified: GII.4_Sydney[P31] (64%, 32/50), GII.6[P7] (14%, 7/50), GII.17[P17] (6%, 3/50), GII.1[P33] (6%, 3/50), GII.3[P16] (4%, 2/50), GII.2[P16] (2%, 1/50), GII.2[P2] (2%, 1/50), and GII.4_New Orleans[P4] (2%, 1/50). Distinct GII.6[P7] variants were recognized, indicating the presence of different co-circulating strains. Elucidating norovirus genetic diversity will improve our understanding of their potential health burden, in particular for the GII.4_Sydney[P31] variant.

Norovirus Infections and Disease in Lower-MiddleandLow-Income Countries, 1997⁻2018

Noroviruses are a major cause of viral gastroenteritis. The burden of the norovirus in low-resource settings is not well-established due to limited data. This study reviews the norovirus prevalence, epidemiology, and genotype diversity in lower-middle-income countries (LMIC) and in low-income countries (LIC). PubMed was searched up to 14 January 2019 for norovirus studies from all LIC and LMIC (World Bank Classification). Studies that tested gastroenteritis cases and/or asymptomatic controls for norovirus by reverse transcription-polymerase chain reaction (RT-PCR) were included. Sixty-four studies, the majority on children <5 years of age, were identified, and 14% (95% confidence interval; CI 14–15, 5158/36,288) of the gastroenteritis patients and 8% (95% CI 7–9, 423/5310) of healthy controls tested positive for norovirus. In LMIC, norovirus was detected in 15% (95% CI 15–16) of cases and 8% (95% CI 8–10) of healthy controls. In LIC, 11% (95% CI 10–12) of symptomatic cases and 9% (95% CI 8–10) of asymptomatic controls were norovirus positive. Norovirus genogroup II predominated overall. GII.4 was the predominant genotype in all settings, followed by GII.3 and GII.6. The most prevalent GI strain was GI.3. Norovirus causes a significant amount of gastroenteritis in low-resource countries, albeit with high levels of asymptomatic infection in LIC and a high prevalence of coinfections.

Epidemiologic and Genotypic Distribution of Noroviruses Among Children With Acute Diarrhea and Healthy Controls in a Low-income Rural Setting

Background

Noroviruses are the most common cause of epidemic and endemic acute gastroenteritis (AGE) worldwide. The burden of norovirus disease in low-income settings is poorly understood.

Methods

We tested stool samples from children less than 5 years of age with diarrhea who were admitted in a rural hospital in Bangladesh from 2010–2012 and from matched, healthy controls from the same catchment area.

Results

Norovirus was detected in 109 (18%) of 613 children with diarrhea and in 30 (15%) of 206 healthy controls. Most (n = 118; 85%) norovirus infections belonged to genogroup II (GII). Of these, GII.4 viruses were identified in 36 (33%) of the cases and in 6 (21%) of the controls. Other major genotypes included GII.3 (13%), GII.6 (11%), and GII.13 (11%) in the cases and GII.6 (17%) and GII.2 (14%) in the controls. The greatest risk of severe norovirus disease (Vesikari score ≥11) was associated with GII.4 infections. GII.4 viruses were the predominant genotype detected during the winter (55%) and rainy season (23%), while GII.3 (19%) and GII.13 (19%) viruses were the most prevalent genotypes during the summer. Vomiting was significantly associated with GII.4 infections, while longer durations of diarrhea were associated with GI.3 infections.

Conclusions

Future studies are needed to understand the high rates of virus shedding in children without AGE symptoms.

Community-based surveillance of norovirus disease: a systematic review

BACKGROUND

Norovirus is a common cause of infectious gastrointestinal disease. Despite the increased ability to detect norovirus in affected people, the number of reported cases and outbreaks in the community is still substantially underestimated. We undertook a systematic review to determine the nature, scope and scale of community-based surveillance systems which capture information on norovirus disease.

METHODS

We searched MEDLINE, EMBASE and Scopus for studies published between 01 January 1995 and 31 December 2015, using terms relating to norovirus and surveillance. Publications were screened independently by two reviewers using exclusion criteria. Data extraction from included papers was performed using a standardized data extraction form. Outcomes were descriptions of the methods reported in included papers, and any estimates of incidence rate of norovirus disease in each community, stratified by age.

RESULTS

After exclusions, we reviewed 45 papers of which 23 described surveillance studies and 19 included estimates of incidence. The estimates of incidence varied by outcome measure, type of laboratory test and study population. There were two estimates of norovirus hospitalisation; 0.72 and 1.04 per 1000 person-years. Estimates of norovirus disease ranged between 0.024 cases per 1000 person-years and 60 cases per 1000 person-years and estimates of all gastroenteritis varied between 49 and 1100 cases per 1000 person-years.

CONCLUSIONS

Our systematic review found few papers describing community-based surveillance for norovirus disease. Standardised age-specific estimates of norovirus incidence would be valuable for calculating the true global burden of norovirus disease; robust community surveillance systems would be able to produce this information.

TRIAL REGISTRATION

PROSPERO 2016: CRD42016048659 .

Norovirus diarrhea in Bangladesh, 2010-2014: prevalence, clinical features, and genotypes

Norovirus infections in diarrhea patients attending an urban and a rural hospital in Bangladesh were investigated. A total of 953 fecal specimens from both children and adults collected during 2010-2014 were tested for the presence of norovirus using real time PCR. One fourth (25%) of the specimens were positive for norovirus RNA which was identified both in children and adults. Norovirus was associated with short duration of diarrhea, high abdominal pain, and more moderate to severe dehydration when compared with rotavirus infections. Norovirus GII (69%) was the most prevalent genogroup followed by GI (18%), mixed GI/GII/GIV (11%), and GIV (2%). Among GII genogroup, GII.4 (42%) was the most prevalent genotype followed by GII.3 (21%), GII.6 (7%), GII.7 (6%), and GII.21 (6%). GII.4 and GII.3 strains were frequently identified (82% and 75%, respectively) in children <2 years of age and less commonly (16% and 15%) in adults more than 18 years of age. The present study reinforces the importance of norovirus-associated hospitalizations both in children and adults. The dynamic molecular epidemiology of norovirus requires routine strain surveillance to identify changes in prevailing strains. J. Med. Virol. 88:1742-1750, 2016. © 2016 Wiley Periodicals, Inc.

Genetic characterization of norovirus strains in hospitalized children from Pakistan

Norovirus is one of the most common causes of acute gastroenteritis among children in developing countries. No data on the prevalence and genetic variability of norovirus are available for Pakistan, where early childhood mortality due to acute gastroenteritis is common. We tested 255 fecal specimens from children under 5 years of age hospitalized between April 2006 and March 2008 with severe acute gastroenteritis in five hospitals in the four largest cities in Pakistan for norovirus by real-time RT-PCR. Positive samples were further genotyped by conventional RT-PCR targeting the 5'-end of the capsid gene followed by sequencing of the positive PCR products. Overall, 41 (16.1%) samples tested positive for norovirus with an equal frequency in rotavirus-positive and rotavirus-negative samples. Nine (22%) samples were genogroup (G)I positive, 30 (73%) GII positive and two (5%) samples contained a mixture of GI and GII viruses. Sequence analyses demonstrated co-circulation of 14 norovirus genotypes including four GI genotypes (GI.3, GI.5, GI.7, GI.8) and 10 GII genotypes (GII.2, GII.3, GII.4, GII.5, GII.6, GII.7, GII.9, GII.13, GII.16, and GII.21). The most prevalent genotypes were GI.7 and GII.4 both causing 12.2% of the infections. This report confirms the presence of multiple norovirus genotypes in hospitalized children with acute gastroenteritis in Pakistan and a lack of clear predominance of GII.4 viruses.

Novel intergenotype human norovirus recombinant GII.16/GII.3 in Bangladesh

Noroviruses (NoVs) are one of the major etiological agents of acute gastroenteritis in all age groups. In this study, we identified an intergenotype NoV recombinant strain in the fecal specimens of two male infants with acute diarrhea in Bangladesh. Phylogenetic analysis showed that the identified strains were recombinant NoV strains with a GII.3 capsid and a GII.16 polymerase gene. The recombination breakpoint was located in the ORF1/ORF2 overlap region. To the best of our knowledge this is the first report of a NoV recombinant GII.16/GII.3 strain worldwide.