Norovirus Acute Gastroenteritis Research Articles

Household economic costs of norovirus gastroenteritis in two community cohorts in Peru, 2012-2019.

While costs of norovirus acute gastroenteritis (AGE) to healthcare systems have been estimated, out-of-pocket and indirect costs incurred by households are not well documented in community settings, particularly in developing countries. We conducted active surveillance for AGE in two communities in Peru: Puerto Maldonado (October 2012-August 2015) and San Jeronimo (April 2015-April 2019). Norovirus AGE events with PCR-positive stool specimens were included. Data collected in follow-up interviews included event-related medical resource utilization, associated out-of-pocket costs, and indirect costs. There were 330 norovirus-associated AGE events among 3,438 participants from 685 households. Approximately 49% of norovirus events occurred among children <5 years of age and total cost to the household per episode was highest in this age group. Norovirus events cost a median of US $2.95 (IQR $1.04-7.85) in out-of-pocket costs and $12.58 (IQR $6.39-25.16) in indirect costs. Medication expenses accounted for 53% of out-of-pocket costs, and productivity losses accounted for 59% of the total financial burden on households. The frequency and associated costs of norovirus events to households in Peruvian communities support the need for prevention strategies including vaccines. Norovirus interventions targeting children <5 years of age and their households may have the greatest economic benefit.

Household economic costs of norovirus gastroenteritis in two community cohorts in Peru, 2012-2019.

While costs of norovirus acute gastroenteritis (AGE) to healthcare systems have been estimated, out-of-pocket and indirect costs incurred by households are not well documented in community settings, particularly in developing countries. We conducted active surveillance for AGE in two communities in Peru: Puerto Maldonado (October 2012-August 2015) and San Jeronimo (April 2015-April 2019). Norovirus AGE events with PCR-positive stool specimens were included. Data collected in follow-up interviews included event-related medical resource utilization, associated out-of-pocket costs, and indirect costs. There were 330 norovirus-associated AGE events among 3,438 participants from 685 households. Approximately 49% of norovirus events occurred among children <5 years of age and total cost to the household per episode was highest in this age group. Norovirus events cost a median of US $2.95 (IQR $1.04-7.85) in out-of-pocket costs and $12.58 (IQR $6.39-25.16) in indirect costs. Medication expenses accounted for 53% of out-of-pocket costs, and productivity losses accounted for 59% of the total financial burden on households. The frequency and associated costs of norovirus events to households in Peruvian communities support the need for prevention strategies including vaccines. Norovirus interventions targeting children <5 years of age and their households may have the greatest economic benefit.

Epidemiological characteristics of norovirus acute gastroenteritis outbreaks and influencing factors in China, 2007-2021

Objective: To analyze the epidemiological characteristics of norovirus-caused acute gastroenteritis outbreaks in China, identify the factors influencing the scale of outbreaks, and provide scientific evidences for early control of norovirus infection outbreaks. Methods: The descriptive epidemiological analysis approach was applied to analyze the incidence of national norovirus infection outbreaks by using the data from the Public Health Emergency Event Surveillance System in China from January 1, 2007 to December 31, 2021. The unconditional logistic regression model was applied to analyze the risk factors that affected the outbreaks' scale. Results: A total of 1 725 norovirus infection outbreaks were recorded in China from 2007 to 2021, with an upward trend in the number of the reported outbreaks. The southern provinces had their annual outbreak peaks from October to March; the northern provinces had two outbreak peaks from October to December and from March to June annually. The outbreaks occurred mainly in southeastern coastal provinces with a trend of gradual spread to central, northeastern and western provinces. The outbreaks mainly occurred in schools and childcare setting (1 539 cases, 89.22%), followed by enterprises and institutions (67 cases, 3.88%) and community households (55 cases, 3.19%). Human to human transmission was the main infection route (73.16%), and norovirus GⅡ genotype was the predominate pathogen causing the outbreaks (899 cases, 81.58%). The time interval between the onset of the primary case and the outbreak reporting M (Q1, Q3) was 3 (2, 6) days and the case number of the outbreak M (Q1, Q3) was 38 (28, 62). The timeliness of outbreak reporting was improved in recent years and the scale of the outbreaks showed a decreasing trend over the years, the differences in reporting timeliness and outbreak scale among different settings were significant (P<0.001). The factors that affected outbreaks' scale included the outbreak setting, transmission route, outbreak reporting timeliness and type of living areas (P<0.05). Conclusions: From 2007 to 2021, the number of the norovirus-caused acute gastroenteritis outbreaks increased in China and the more areas were affected. However, the outbreak scale showed a decreasing trend and the outbreak reporting timeliness was improved. It is important to further improve the surveillance sensitivity and reporting timeliness for the effective control of the outbreak scale.

Norovirus acute gastroenteritis among US and European travellers to areas of moderate to high risk of travellers' diarrhoea: a prospective cohort study.

Acute gastroenteritis (AGE) is a major medical condition for travellers worldwide, particularly travellers to low- and middle-income countries. Norovirus (NoV) is the most common cause of viral AGE in older children and adults, but data on prevalence and impact among travellers is limited. Prospective, multi-site, observational cohort study conducted 2015-2017, among adult international travellers from the US and Europe to areas of moderate to high risk of travel-acquired AGE. Participants provided self-collected pre-travel stool samples and self-reported AGE symptoms while travelling. Post-travel stool samples were requested from symptomatic subjects and a sample of asymptomatic travellers within 14days of return. Samples were tested for NoV by RT-qPCR, genotyped if positive, and tested for other common enteric pathogens by Luminex xTAG GPP. Of the 1109 participants included, 437 (39.4%) developed AGE symptoms resulting in an overall AGE incidence of 24.7 per 100 person-weeks (95% CI: 22.4; 27.1). Twenty NoV-positive AGE cases (5.2% of those tested) were identified at an incidence of 1.1 per 100 person-weeks (95% CI: 0.7; 1.7). NoV-positive samples belonged mostly to genogroup GII (18, 85.7%); None of the 13 samples sequenced belonged to genotype GII.4. Clinical severity of AGE was higher for NoV-positive than for NoV-negative cases (mean modified Vesikari Score 6.8 vs 4.9) with more cases classified as severe or moderate (25% vs 6.8%). Eighty percent of NoV-positive participants (vs. 38.9% in NoV-negative) reported at least moderate impact on travel plans. AGE is a prevalent disease among travellers with a small proportion associated with NoV. Post-travel stool sample collection timing might have influenced the low number of NoV cases detected; however, NoV infections resulted in high clinical severity and impact on travel plans. These results may contribute to targeted vaccine development and the design of future studies on NoV epidemiology.

Household Surveillance for Norovirus Gastroenteritis in a Nicaraguan Birth Cohort: A Nested Case-Control Analysis of Norovirus Risk Factors.

Norovirus causes a large proportion of pediatric acute gastroenteritis (AGE) worldwide, and no vaccines are currently available. To inform public health measures against norovirus gastroenteritis, we assessed risk factors in a case-control study nested in a birth cohort study in Nicaragua. Between June 2017 and January 2022, we followed children weekly for AGE episodes, and collected stool specimens from symptomatic children. Risk factors for AGE were collected during routine weekly visits. Norovirus was detected in stools using real-time reverse transcriptase polymerase chain reaction and positive specimens were genotyped using Sanger sequencing. We included 40 norovirus-positive AGE children matched 1:2 to controls and conducted bivariate and multivariable analyses of norovirus AGE risk factors. Among typeable norovirus infections, GII.4 were more severe than non-GII.4 (four/twenty-one vs. one/nine) and accounted for all emergency visits and hospitalizations. Adjusted conditional logistic regression found that female sex and higher length-for-age Z score were protective against norovirus AGE; a dirt floor in the home, sharing cups or bottles, and recent contact with someone with AGE symptoms were associated with norovirus AGE, though estimates were highly imprecise. Reducing contact with symptomatic persons and with saliva or other bodily fluids on cups or floors could reduce infant norovirus incidence.

CARDIOGENIC SHOCK ASSOCIATED WITH ACUTE NOROVIRUS GASTROENTERITIS: WHAT IS NEEDED TO PROVE CAUSALITY?

Viral myocarditis exhibits a wide spectrum of symptoms ranging from non-specific prodromes such as fatigue and myalgia to chest pain, life-threatening arrhythmias, fulminant heart failure, or even sudden cardiac death.Common viral aetiologies for myocarditis include enteroviruses including coxsackie, adenovirus, influenza, echovirus, parvovirus B19 and herpesvirus.A high index of suspicion, early diagnosis, and prompt management with supportive anti-failure measures, and in selected cases immunosuppressive therapies including high-dose steroids, might be considered for better outcomes in cases of acute myocarditis.

Asymptomatic Norovirus Infection Among Children in Kindergartens and Primary Schools - Beijing Municipality, China, 2021.

Children in kindergartens and primary schools are the high-incidence groups of norovirus acute gastroenteritis. However, asymptomatic norovirus infection among them is seldom reported. The norovirus positive rate was 3.48% among asymptomatic children in kindergartens and primary schools in Beijing Municipality in June 2021, the most common genotype was GII.4 Sydney, and no acute gastroenteritis outbreak was reported over the study period. The asymptomatic norovirus infection was relatively low among kindergarten children and primary school students in summer. Norovirus genotypes in asymptomatic children were similar to those circulating in the symptomatic cases. Asymptomatic norovirus infection may play a limited role in causing acute gastroenteritis outbreaks.

Association between breastfeeding, host genetic factors, and calicivirus gastroenteritis in a Nicaraguan birth cohort.

Norovirus and sapovirus are important causes of childhood acute gastroenteritis (AGE). Breastfeeding prevents AGE generally; however, it is unknown if breastfeeding prevents AGE caused specifically by norovirus and sapovirus. We investigated the association between breastfeeding and norovirus or sapovirus AGE episodes in a birth cohort. Weekly data on breastfeeding and AGE episodes were captured during the first year of life. Stools were collected from children with AGE and tested by RT-qPCR for norovirus and sapovirus. Time-dependent Cox models estimated associations between weekly breastfeeding and time to first norovirus or sapovirus AGE. From June 2017 to July 2018, 444 newborns were enrolled in the study. In the first year of life, 69 and 34 children experienced a norovirus and a sapovirus episode, respectively. Exclusive breastfeeding lasted a median of 2 weeks, and any breastfeeding lasted a median of 43 weeks. Breastfeeding in the last week did not prevent norovirus (HR: 1.09, 95% CI: 0.62, 1.92) or sapovirus (HR: 1.00, 95% CI: 0.82, 1.21) AGE in a given week, adjusting for household sanitation, consumption of high-risk foods, and mother's and child's histo-blood group phenotypes. Maternal secretor-positive phenotype was protective against norovirus AGE, whereas child's secretor-positive phenotype was a risk factor for norovirus AGE. Exclusive breastfeeding in this population was short-lived, and no conclusions could be drawn about its potential to prevent norovirus or sapovirus AGE. Non-exclusive breastfeeding did not prevent norovirus or sapovirus AGE in the first year of life. However, maternal secretor-positive phenotype was associated with a reduced hazard of norovirus AGE.

Norovirus Infection in Young Nicaraguan Children Induces Durable and Genotype-Specific Antibody Immunity.

There are significant challenges to the development of a pediatric norovirus vaccine, mainly due to the antigenic diversity among strains infecting young children. Characterizing human norovirus serotypes and understanding norovirus immunity in naïve children would provide key information for designing rational vaccine platforms. In this study, 26 Nicaraguan children experiencing their first norovirus acute gastroenteritis (AGE) episode during the first 18 months of life were investigated. We used a surrogate neutralization assay that measured antibodies blocking the binding of 13 different norovirus virus-like particles (VLPs) to histo-blood group antigens (HBGAs) in pre- and post-infection sera. To assess for asymptomatic norovirus infections, stools from asymptomatic children were collected monthly, screened for norovirus by RT-qPCR and genotyped by sequencing. Seroconversion of an HBGA-blocking antibody matched the infecting genotype in 25 (96%) of the 26 children. A subset of 13 (50%) and 4 (15%) of the 26 children experienced monotypic GII and GI seroconversion, respectively, strongly suggesting a type-specific response in naïve children, and 9 (35%) showed multitypic seroconversion. The most frequent pairing in multitypic seroconversion (8/12) were GII.4 Sydney and GII.12 noroviruses, both co-circulating at the time. Blocking antibody titers to these two genotypes did not correlate with each other, suggesting multiple exposure rather than cross-reactivity between genotypes. In addition, GII titers remained consistent for at least 19 months post-infection, demonstrating durable immunity. In conclusion, the first natural norovirus gastroenteritis episodes in these young children were dominated by a limited number of genotypes and induced responses of antibodies blocking binding of norovirus VLPs in a genotype-specific manner, suggesting that an effective pediatric norovirus vaccine likely needs to be multivalent and include globally dominant genotypes. The duration of protection from natural infections provides optimism for pediatric norovirus vaccines administered early in life.

First Episodes of Norovirus and Sapovirus Gastroenteritis Protect Against Subsequent Episodes in a Nicaraguan Birth Cohort.

Norovirus and sapovirus cause a large burden of acute gastroenteritis (AGE) in young children. We assessed protection conferred by norovirus and sapovirus AGE episodes against future episodes. Between June 2017 and July 2018, we recruited 444 newborns in León, Nicaragua. Weekly household surveys identified AGE episodes over 36 months, and AGE stools were tested by reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) for norovirus genogroup (G)I/GII and sapovirus. We used recurrent-event Cox models and negative control methods to estimate protection conferred by first episodes, controlling for observed and unobserved risk factors, respectively. Sapovirus episodes conferred a 69% reduced hazard of subsequent episodes using the negative control method. Norovirus GI (hazard ratio [HR] = 0.67; 95% confidence interval [CI] = 0.31, 1.3) and GII (HR = 0.20; 95% CI = 0.04, 0.44) episodes also appeared highly protective. Protection against norovirus GII was enhanced following two episodes. Evidence of natural immunity in early childhood provides optimism for the future success of pediatric norovirus and sapovirus vaccines.

Acute norovirus gastroenteritis in up to five years children highly rotavirus-vaccinated population in southern Brazil

The acute gastroenteritis remains a problem social, economic and of the public health of the global impact and among the main causative agents are the viruses. This study aimed to show the circulation of rotavirus (RoV) and norovirus (NoV) infections in children under 5 years, vaccinated or not against RoV, enrolled in the health system presented gastroenteritis. From March 2011 to February 2012 a total of 160 stool samples were collected, overall positivity rates were 11.9% (19/160) for NoV and was not found infected patients with RV. The children include had a mean of 2.8 and a median of 3 years of old, and the average of rotavirus vaccination rate was 83.85%. This result shows that this circulating NoV and suggests a reduction in the occurrence of RoV infection in children with high vaccination coverage rate.

Molecular Epidemiology of Norovirus (NoV) Infection in Mie Prefecture: The Kinetics of Norovirus Antigenemia in Pediatric Patients.

Few studies have shown the presence of norovirus (NoV) RNA in blood circulation but there is no data on norovirus antigenemia. We examined both antigenemia and RNAemia from the sera of children with NoV infections and studied whether norovirus antigenemia is correlated with the levels of norovirus-specific antibodies and clinical severity of gastroenteritis. Both stool and serum samples were collected from 63 children admitted to Mie National Hospital with acute NoV gastroenteritis. Norovirus antigen and RNA were detected in sera by ELISA and real-time RT-PCR, respectively. NoV antigenemia was found in 54.8% (34/62) and RNAemia in 14.3% (9/63) of sera samples. Antigenemia was more common in the younger age group (0–2 years) than in the older age groups, and most patients were male. There was no correlation between stool viral load and norovirus antigen (NoV-Ag) levels (rs = −0.063; Cl −0.3150 to 0.1967; p = 0.6251). Higher levels of acute norovirus-specific IgG serum antibodies resulted in a lower antigenemia OD value (n = 61; r = −0.4258; CI −0.62 to −0.19; p = 0.0006). Norovirus antigenemia occurred more commonly in children under 2 years of age with NoV-associated acute gastroenteritis. The occurrence of antigenemia was not correlated with stool viral load or disease severity.

Secretor Status Strongly Influences the Incidence of Symptomatic Norovirus Infection in a Genotype-Dependent Manner in a Nicaraguan Birth Cohort.

The role of histo-blood group on the burden and severity of norovirus gastroenteritis in young infants has not been well documented. Norovirus gastroenteritis was assessed in 443 Nicaraguan children followed from birth until 3 years of age. Stool samples were tested for norovirus by reverse-transcription quantitative polymerase chain reaction (RT-qPCR), and histo-blood group antigens (HBGAs) were determined by phenotyping of saliva and blood. Hazard ratios and predictors of norovirus acute gastroenteritis (AGE) outcome stratified by HBGA were estimated using Cox proportional hazards models. Of 1353 AGE episodes experienced by children, 229 (17%) tested positive for norovirus with an overall incidence of 21.9/100 child-years. Secretor children were infected as early as 2 months of age and had a higher incidence of norovirus GII compared to nonsecretor children (15.4 vs 4.1/100 child-years, P = .006). Furthermore, all GII.4 AGE episodes occurred in secretor children. Children infected with GI (adjusted odds ratio [aOR], 0.09 [95% confidence interval {CI}, .02-.33]) or non-GII.4 viruses (aOR, 0.2 [95% CI, .07-.6]) were less likely to have severe AGE compared to GII.4-infected children. Secretor status in children strongly influences the incidence of symptomatic norovirus infection in a genogroup or genotype-dependent manner and provides evidence that clinical severity in children depends on norovirus genotypes.

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

Globally, noroviruses are recognized as an important cause of acute gastroenteritis (AGE), but data from low and middle-income countries are limited. To examine the epidemiology and strain diversity of norovirus infections among children hospitalized for AGE in Bangladesh. 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. 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). Norovirus is an important cause of AGE hospitalization in Bangladeshi children with most infections caused by GII viruses.

Norovirus compared to other relevant etiologies of acute gastroenteritis among families from a semirural county in Chile

ObjectiveTo determine the dynamics of norovirus disease, a major cause of acute gastroenteritis (AGE), compared to other relevant etiologies, among families living in a lower middle income area. Study designFamilies with three or more members and with one or more healthy children <24 months of age were followed for 1–2 years to detect any AGE. Stool samples were tested for viral and bacterial pathogens and a questionnaire was completed for those with norovirus or rotavirus AGE. ResultsBetween April and June 2016, 110 families were enrolled, with 103 of them completing ≥12 months of follow-up. A total of 159 family AGE episodes were detected, mostly affecting one individual (92%). At least one pathogen was detected in 56% (94/169) of samples, of which 75/94 (80%) were sole infections. Norovirus was most common (n=26), followed closely by enteropathogenic Escherichia coli (EPEC) (n=25), rotavirus (n=24), and astrovirus (n=23). The annual incidence of family AGE was 0.77, and 0.12 for norovirus. Most norovirus AGE occurred in children <4 years old (96%). Only 13/159 (8%) index AGE cases resulted in a secondary case, of which four were associated with norovirus. The majority of norovirus strains were GII (85%), with a mild predominance of GII.4 (9/26; 35%); most norovirus isolates (69%) were recombinants. ConclusionsThe family incidence of AGE in this lower middle income community was nearly one episode per year, mostly caused by viruses, specifically norovirus closely followed by rotavirus and astrovirus. Norovirus infections primarily affected children <4 years old and secondary cases were uncommon.

Efficacy of an intramuscular bivalent norovirus GI.1/GII.4 virus-like particle vaccine candidate in healthy US adults

BackgroundWe performed this first-in-human efficacy trial of Takeda’s bivalent norovirus vaccine candidate (TAK-214) against moderate or severe acute gastroenteritis (AGE) in healthy adults. MethodsThis double-blind, randomized, placebo-controlled phase 2b trial was conducted over two winter seasons in 18–49 year-old US Navy recruits. Participants were randomized (1:1) to receive intramuscular injections of saline placebo (N = 2,357) or TAK-214 [15 μg GI.1 and 50 μg GII.4c VLPs, 0.5 mg Al(OH)3] (N = 2,355), and monitored for 45 days post-vaccination for AGE. Norovirus genotypes were identified by RT-PCR and sequencing of stool/vomitus samples. Sera from AGE cases were used to assess immune responses as genotype-specific histo-blood group antigen (HBGA)-blocking antibodies. FindingsWith low rates of homotypic norovirus AGE detected the statistical analysis was proactively modified to account for AGE due to any norovirus genotype. Of the 48 norovirus AGE cases of “any severity”, 29 in placebo and 19 in vaccinees, causative genotypes were GI.1 (n = 1), G1.7a (n = 1), GII.2 (n = 39) and GII.4 (n = 7). Applying predefined definitions of moderate or severe AGE gave 26 vs. 10 cases due to any norovirus genotype in placebo vs. vaccine groups, a vaccine efficacy (VE) of 61.8% (95.01% CI, 20.8 to 81.6; p = 0.0097). Five vs. one moderate or severe cases due to vaccine GI.1/GII.4 homotypic genotypes in placebo vs. vaccine arms gave a primary endpoint vaccine efficacy of 80.0% (99.99% CI, −1318.1 to 99.7; p = 0.142). Levels of GI.1 and GII.4 HBGA-blocking antibodies were increased in vaccinees and in some placebo AGE cases infected with GII.2, indicating cross-reactivity in the immune responses to different genotypes. InterpretationDespite limited cases of homotypic norovirus AGE meaning the primary endpoint was not fully evaluable, we showed TAK-214 provided statistically significant efficacy against “any moderate/severe norovirus AGE” principally caused by the heterotypic GII.2 genotype, demonstrating induction of cross-genotype protection.

Clinical characteristics and risk factors for children with norovirus gastroenteritis in Taiwan.

Norovirus is a common acute gastroenteritis (AGE) pathogen across all age groups worldwide, which is difficult to differentiate from other pathogens. This study aimed to understand the clinical characteristics and risk factors of norovirus gastroenteritis among children in Taiwan. A prospective AGE surveillance study was conducted in children aged ≤5 years who were hospitalized in 10 major hospitals in Taiwan between 2014 and 2017. The non-AGE control group included healthy children who were matched based on age, gender, season, and geographic area. Overall, 674 norovirus gastroenteritis patients were enrolled. Fever (p<0.001), mucoid stool (p<0.001), and bloody stool (p<0.001) occurred less frequently among norovirus gastroenteritis patients. Norovirus gastroenteritis patients yielded lower CRP values on admission (21.78±36.81 vs. 46.26±58.12mg/L, p<0.001) than non-norovirus controls. Norovirus gastroenteritis patients were associated with higher direct contact rates with AGE patients within 1 week (30.5% vs. 0.97%, p<0.001), lower hand wash rates before meals (21.6% vs. 15.4%, p=0.001), lower human milk (15.8% vs. 19.8%, p=0.045) and guava consumption rates (17.8% vs. 24.3%, p=0.002) than non-AGE participants. Body temperature, stool characteristics, and CRP value can help distinguish the norovirus from other pathogens. The major risk factor of norovirus AGE is contact with AGE patient. Higher frequency of hand wash, human milk, and guava intake may be protective against norovirus gastroenteritis.

Characteristics of GII.4 Norovirus Versus Other Genotypes in Sporadic Pediatric Infections in Davidson County, Tennessee, USA.

BackgroundNorovirus is a leading cause of epidemic acute gastroenteritis (AGE), with most outbreaks occurring during winter. The majority of outbreaks are caused by GII.4 noroviruses; however, data to support whether this is true for sporadic medically attended AGE are limited. Therefore, we sought to compare the clinical characteristics and seasonality of GII.4 vs non-GII.4 viruses.MethodsChildren aged 15 days -17 years with AGE symptoms were recruited from the outpatient, emergency department, and inpatient settings at Vanderbilt Children’s Hospital, Davidson County, Nashville, Tennessee, from December 2012 -November 2015. Stool specimens were tested using qRT-PCR for GI and GII noroviruses and subsequently genotyped by sequencing a partial region of the capsid gene.ResultsA total of 3705 patients were enrolled, and stool specimens were collected and tested from 2885 (78%) enrollees. Overall, 636 (22%) samples were norovirus-positive, of which 567 (89%) were GII. Of the 460 (81%) genotyped GII-positive samples, 233 (51%) were typed as GII.4 and 227 (49%) as non-GII.4. Compared with children with non-GII.4 infections, children with GII.4 infections were younger, more likely to have diarrhea, and more likely to receive oral rehydration fluids. Norovirus was detected year-round and peaked during winter.ConclusionsApproximately 40% of sporadic pediatric norovirus AGE cases were caused by GII.4 norovirus. Children infected with GII.4 had more severe symptoms that required more medical care. Seasonal variations were noticed among different genotypes. These data highlight the importance of continuous norovirus surveillance and provide important information on which strains pediatric norovirus vaccines should protect against.

Norovirus detection in environmental samples in norovirus outbreaks in closed and semi-closed settings

Environmental surfaces are a potential vehicle for the transmission of norovirus outbreaks in closed and semi-closed settings. Testing of environmental samples may help control outbreaks. To assess the level of environmental contamination by norovirus in acute gastroenteritis outbreaks in closed or semi-closed settings (nursing homes, schools, kindergartens, youth accommodations, hospitals and social health centres) in the Barcelona region between January 2017 and March 2019. A prospective surveillance study was carried out. Environmental samples (529) were collected in 46 of the 50 outbreaks of acute norovirus gastroenteritis from environmental surfaces of common areas, bathrooms and kitchens in closed and semi-closed settings when the outbreak was notified and 10 days later. Instructions for taking environmental samples were distributed to public health inspectors. Norovirus was detected by reverse transcription polymerase chain reaction. Environmental samples were positive for norovirus in 31 (67.4%) outbreaks. Norovirus was most frequently detected on elevator buttons (4/17, 24%), toilet handles (16/66, 24%) and handrail bars (7/34, 21%). Positive samples from the first sampling were mainly found in bathrooms and greater viral persistence in the second sampling was found on elevator buttons and TV remote controls. Nursing homes were the setting with the most types of environmental surfaces contaminated (82% in first samples and 55% in second samples). The probability of virus detection is independent of the time between notification of the outbreak or symptom onset and sample collection. Our results suggest possible defects in cleaning protocols and disinfection in closed and semi-closed settings.

Trends in Incidence of Norovirus-associated Acute Gastroenteritis in 4 Veterans Affairs Medical Center Populations in the United States, 2011-2015.

Norovirus is an important cause of epidemic acute gastroenteritis (AGE), yet the burden of endemic disease in adults has not been well documented. We estimated the prevalence and incidence of outpatient and community-acquired inpatient norovirus AGE at 4 Veterans Affairs Medical Centers (VAMC) (Atlanta, Georgia; Bronx, New York; Houston, Texas; and Los Angeles, California) and examined trends over 4 surveillance years. From November 2011 to September 2015, stool specimens collected within 7 days of AGE symptom onset for clinician-requested diagnostic testing were tested for norovirus, and positive samples were genotyped. Incidence was calculated by multiplying norovirus prevalence among tested specimens by AGE-coded outpatient encounters and inpatient discharges, and dividing by the number of unique patients served. Of 1603 stool specimens, 6% tested were positive for norovirus; GII.4 viruses (GII.4 New Orleans [17%] and GII.4 Sydney [47%]) were the most common genotypes. Overall prevalence and outpatient and inpatient community-acquired incidence followed a seasonal pattern, with higher median rates during November-April (9.2%, 376/100 000, and 45/100 000, respectively) compared to May-October (3.0%, 131/100 000, and 13/100 000, respectively). An alternate-year pattern was also detected, with highest peak prevalence and outpatient and inpatient community-acquired norovirus incidence rates in the first and third years of surveillance (14%-25%, 349-613/100 000, and 43-46/100 000, respectively). This multiyear analysis of laboratory-confirmed AGE surveillance from 4 VAMCs demonstrates dynamic intra- and interannual variability in prevalence and incidence of outpatient and inpatient community-acquired norovirus in US Veterans, highlighting the burden of norovirus disease in this adult population.