Norovirus and medically attended gastroenteritis in U.S. children

Presence of immune deficiency increases the risk of hospitalization in patients with norovirus infection

Norovirus is an emerging pathogen causing gastroenteritis. We sought to identify factors associated with clinical outcomes in a cohort of patients with laboratory-confirmed norovirus infection. We performed a retrospective chart review of patients with positive norovirus polymerase chain reaction in stool between October 1, 2015, and May 31, 2016. 128 unique patients were identified during the study period, 64 of whom had immune deficiency, of which only 3 patients had a primary immune deficiency (common variable immune deficiency), while 61 patients had a secondary immune deficiency. 50% of patients with immune deficiency were hospitalized as compared to only 30% of the non-immune-deficient cohort (odds ratio: 2.1 (1.1-4.18, P=0.04). One-third (32.8%) of the patients had a polymicrobial stool infection, and 21.1% had concurrent Clostridium difficile infection. Initial mean total leukocyte count was higher in the hospitalized group at 8.40×109/L versus 6.31×109/L in the nonhospitalized group (P=0.049). All 13 patients presenting with fever had symptomatic resolution (P=0.002). The presence of C. difficile infection was correlated with persistent symptoms (OR 2.30 [0.95-5.58], P=0.067). The overall mortality rate among our cohort was 3.13% (4 patients). All deceased patients had secondary immune deficiency, and none had C. difficile coinfection. Presence of an immune deficiency increases the risk of hospitalization with norovirus infection. Absence of fever is associated with lower resolution and possibly may contribute to a persistent infectious state. Presence of concomitant C. difficile infection is correlated with a lower overall mortality rate.

Transmission of respiratory and gastrointestinal infections in German households with children attending child care

Transmission of acute respiratory infections (ARI) and acute gastroenteritis (AGE) often occurs in households. The aim of this study was to assess which proportion of ARI and AGE is introduced and transmitted by children in German households with children attending child care. We recruited families with children aged 0-6 years in Braunschweig (Germany), for a 4 months prospective cohort study in the winter period 2014/2015. Every household member was included in a health diary and used nasal swabs for pathogen identification in case of ARI. We defined a transmission if two persons had overlapping periods with symptoms and used additional definitions for sensitivity analyses. In total, 77 households participated with 282 persons. We observed 277 transmission events for ARI and 23 for AGE. In most cases, the first infected person in a household was a child (ARI: 63%, AGE: 53%), and the risk of within-household transmission was two times higher when the index case was a child. In 26 ARI-transmission events, pathogens were detected for both cases; hereof in 35% (95% confidence interval (17-56%)) the pathogens were different. Thus, symptomatic infections in household members, apparently linked in time, were in 2/3 associated with the same pathogens.

Human organoid cultures: transformative new tools for human virus studies

Studies of human infectious diseases have been limited by the paucity of functional models that mimic normal human physiology and pathophysiology. Recent advances in the development of multicellular, physiologically active organotypic cultures produced from embryonic and pluripotent stem cells, as well as from stem cells isolated from biopsies and surgical specimens are allowing unprecedented new studies and discoveries about host-microbe interactions. Here, we summarize recent developments in the use of organoids for studying human viral pathogens, including intestinal infections with human rotavirus, norovirus, enteroviruses and adenoviruses (intestinal organoids and enteroids), neuronal infections with Zika virus (cerebral organoids) and respiratory infections with respiratory syncytial virus in (lung bud organoids). Biologic discovery of host-specific genetic and epigenetic factors affecting infection, and responses to infection that lead to disease are possible with the use of organoid cultures. Continued development to increase the complexity of these cultures by including components of the normal host tissue microenvironment such as immune cells, blood vessels and microbiome, will facilitate studies on human viral pathogenesis, and advance the development of platforms for pre-clinical evaluation of vaccines, antivirals and therapeutics.

The economic burden of rotavirus infection in South Korea from 2009 to 2012

Rotavirus is a common cause of diarrhea worldwide, and vaccination prevents rotaviral gastroenteritis. Since the rotavirus vaccine was introduced in Korea in 2007, the prevalence of rotaviral gastroenteritis has decreased. However, little is known on the economic burden of rotavirus infection and its variations in Korea. Here, we estimated the economic costs of rotavirus infection from 2009 to 2012 using nationwide data from the National Health Insurance Service (NHIS) claims. Socioeconomic costs were subdivided into direct and indirect and measured with a prevalence-based approach. Costs were converted from Won to United States dollars (US$). The number of children <5 years old infected with rotavirus decreased from 21,437 to 10,295 during the study period, representing a decrease in prevalence from 947 to 443 per 100,000. The sum of direct and indirect costs also decreased, from $17.3 million to $9.6 million, and the days of admission decreased from 76,000 to 38,000. However, per capita expenditures slightly increased, from $809 to $934. Thus, the economic burden of rotavirus infection decreased after implementation of rotavirus vaccination. Including the vaccine as part of the national essential vaccination program could reduce the prevalence of and economic loss from rotavirus infection in Korea.

Genetic diversity of norovirus in children under 5 years of age with acute gastroenteritis from Angola

Norovirus (NoV) is a major cause of acute gastroenteritis (AGE). In this study, we investigated the genetic diversity of NoV strains identified in children under 5 years of age with AGE in four provinces of Angola. Faecal samples from 343 children were screened for NoV by an in house real-time PCR assay and genotyping was performed by partial capsid gene sequencing. NoV was detected in 17.4% (58/334) of the samples, with high detection rates in children <6 months old (19%) and in children aged 12-24 months (23%). Genotype diversity was large, as demonstrated by the 11 identified genotypes. GII.4 was the predominant genotype (20% of all NoV-positive samples), followed by GII.6 (15%), GI.3 (12%), GII.7 (10%) and by other genotypes to a lesser extent. Two GII.4 variants, New Orleans 2009 and Sydney 2012, were detected and several genetic clusters were observed for genotypes GI.3, GII.6 and GII.7. The present study shows high detection rates and genetic diversity of circulating NoV genotypes in paediatric AGE samples from Angola. This information emphasises the importance of continuous assessment of NoV burden and evolution in the target population.

Challenges in developing mucosal vaccines and antibodies against infectious diarrhea in children

Infectious diarrhea in children can be life-threatening and imposes a large economic burden on healthcare systems, therefore more effective prophylactic and therapeutic drugs are needed urgently. Because most of the pathogens responsible for childhood diarrhea infect the gastrointestinal mucosa, providing protective immunity at the mucosal surface is an ideal way to control pathogen invasion and toxic activity. Mucosal (e.g. oral, nasal) vaccines are superior to systemic (subcutaneous or intramuscular) vaccination for conferring both mucosal and systemic pathogen-specific immune responses. Therefore, great efforts has been focused on the development of cost-effective mucosal vaccines for the past 50 years. Recent progress in plant genetic engineering has revolutionized the production of inexpensive and safe recombinant vaccine antigens. For example, rice plant biotechnology has facilitated the development of a cold-chain-free rice-based oral subunit vaccine against Vibrio cholerae. Furthermore, this technology has led to the creation of a rice-based oral antibody for prophylaxis and treatment of rotavirus gastroenteritis. This review summarizes current perspectives regarding the mucosal immune system and the development of mucosal vaccines and therapeutic antibodies, particularly rice-based products, and discusses future prospects regarding mucosal vaccines for children.

Norovirus Illnesses in Children and Adolescents

Norovirus is a leading cause of childhood vomiting and diarrhea in the United States and globally. Although most illnesses caused by norovirus are self-resolving, severe outcomes may occur from dehydration, including hospitalization and death. A vast majority of deaths from norovirus occur in developing countries. Immunocompromised children are at risk for more severe outcomes. Treatment of norovirus illness is focused on early correction of dehydration and maintenance of fluid status and nutrition. Hand hygiene, exclusion of ill individuals, and environmental cleaning are important for norovirus outbreak prevention and control, and vaccines to prevent norovirus illness are currently under development.

Significance of continuous rotavirus and norovirus surveillance in Indonesia

BACKGROUND

Diarrhea significantly contributes to the global burden of diseases, particularly in developing countries. Rotavirus and norovirus are the most dominant viral agents responsible for diarrheal disease globally. The aim of this review was to conduct a comprehensive assessment of rotavirus and norovirus study in Indonesia.

DATA SOURCES

Articles about rotavirus and norovirus surveillance in Indonesia were collected from databases, including PubMed and Google Scholar. Manual searching was performed to identify additional studies. Furthermore, relevant articles about norovirus diseases were included.

RESULTS

A national surveillance of rotavirus-associated gastroenteritis has been conducted for years, resulting in substantial evidence about the high burden of the diseases in Indonesia. In contrast, norovirus infection received relatively lower attention and very limited data are available about the incidence and circulating genotypes. Norovirus causes sporadic and epidemic gastroenteritis globally. It is also emerging as a health problem in immunocompromised individuals. During post-rotavirus vaccination era, norovirus potentially emerges as the most frequent cause of diarrheal diseases.

CONCLUSIONS

Our review identifies knowledge gaps in Indonesia about the burden of norovirus diseases and the circulating genotypes. Therefore, there is a pressing need to conduct national surveillance to raise awareness of the community and national health authority about the actual burden of norovirus disease in Indonesia. Continuing rotavirus surveillance is also important to assess vaccine effectiveness and to continue tracking any substantial changes of circulating rotavirus genotypes.

The global problem of childhood diarrhoeal diseases: emerging strategies in prevention and management

Acute diarrhoeal diseases remain a leading cause of global morbidity and mortality particularly among young children in resource-limited countries. Recent large studies utilizing case-control design, prospective sampling and more sensitive and broad diagnostic techniques have shed light on particular pathogens of importance and highlighted the previously under recognized impact of these infections on post-acute illness mortality and growth. Vaccination, particularly against rotavirus, has emerged as a key effective means of preventing significant morbidity and mortality from childhood diarrhoeal disease. Other candidate vaccines against leading diarrhoeal pathogens, such as enterotoxigenic Escherichia coli and Shigella spp., also hold significant promise in further ameliorating the burden of enteric infections in children. Large studies are also currently underway evaluating novel and potential easy-to-implement water, sanitation and hygiene (WASH) preventive strategies. Given the ongoing global burden of this illness, the paucity of new advances in case management over the last several decades remains a challenge. The increasing recognition of post-acute illness mortality and growth impairment has highlighted the need for interventions that go beyond management of dehydration and electrolyte disturbances. The few trials of novel promising interventions such as probiotics have mainly been conducted in high-income settings. Trials of antimicrobials have also been primarily conducted in high-income settings or in travellers from high-income settings. Bloody diarrhoea has been shown to be a poor marker of potentially treatable bacterial enteritis, and rising antimicrobial resistance has also made empiric antimicrobial therapy more challenging in many settings. Novel effective and sustainable interventions and diagnostic strategies are clearly needed to help improve case management. Diarrhoeal disease and other enteric infections remain an unmet challenge in global child health. Most promising recent developments have been focused around preventive measures, in particular vaccination. Further advances in prevention and case management including the possible use of targeted antimicrobial treatment are also required to fully address this critical burden on child health and human potential.

Rotavirus Infection in the Auckland Region After the Implementation of Universal Infant Rotavirus Vaccination: Impact on Hospitalizations and Laboratory Implications

BACKGROUND

In July 2014, New Zealand introduced universal infant vaccination with RotaTeq (Merk & Co.) administered as 3 doses at 6 weeks, 3 and 5 months of age. We sought to assess the impact of rotavirus vaccination on gastroenteritis (GE) hospitalizations in the greater Auckland region and analyze changes in rotavirus testing in the period around vaccine introduction.

METHODS

Hospitalizations, laboratory testing rates and methods were compared between the pre-vaccine period (2009-2013), post-vaccine period (January 2015 to December 2015) and year of vaccine introduction (2014).

RESULTS

There was a 68% decline in rotavirus hospitalizations of children <5 years of age after vaccine introduction (from 258/100,000 to 83/100,000) and a 17% decline in all-cause gastroenteritis admissions (from 1815/100,000 to 1293/100,000). Reductions were also seen in pediatric groups too old to have received vaccine. Despite these changes, rotavirus testing rates in our region remained static in the year after vaccine introduction compared with the 2 prior years, and after vaccine introduction, we observed a high rate of false positives 19/58 (33%) in patients with reactive rotavirus tests.

CONCLUSIONS

Rotavirus vaccine has had a significant early impact on gastroenteritis hospitalizations for children in the Auckland region. However, continued rotavirus testing at pre-vaccine rates risks generating false positive results. Laboratories and clinicians should consider reviewing their testing algorithms before vaccine introduction.

Estimating the Burden of Medically Attended Norovirus Gastroenteritis: Modeling Linked Primary Care and Hospitalization Datasets

Background

Norovirus is the leading cause of community-acquired and nosocomial acute gastroenteritis. Routine testing for norovirus is seldom undertaken, and diagnosis is mainly based on presenting symptoms. This makes understanding the burden of medically attended norovirus-attributable gastroenteritis (MA-NGE) and targeting care and prevention strategies challenging.

Methods

We used linked population-based healthcare datasets (Clinical Practice Research Datalink General Practice OnLine Database linked with Hospital Episode Statistics Admitted Patient Care) to model the incidence of MA-NGE associated with primary care consultations or hospitalizations according to age groups in England in the period July 2007–June 2013.

Results

Mean annual incidence rates of MA-NGE were 4.9/1000 person-years and 0.7/1000 person-years for episodes involving primary care or hospitalizations, respectively. Incidence rates were highest in children aged <5 years: 34.0 consultations/1000 person-years and 3.3 hospitalizations/1000 person-years. Medically attended norovirus-attributable gastroenteritis hospitalization rates were second highest in adults aged >65 years (1.7/1000 person-years).

Conclusions

In this particular study, the burden of MA-NGE estimated from healthcare datasets was higher than previously estimated in small cohort studies in England. Routinely collected primary care and hospitalization datasets are useful resources to estimate and monitor the burden of MA-NGE in a population over time.

The major targets of acute norovirus infection are immune cells in the gut-associated lymphoid tissue

Noroviruses are the leading cause of food-borne gastroenteritis outbreaks and childhood diarrhoea globally, estimated to be responsible for 200,000 deaths in children each year 1-4 . Thus, reducing norovirus-associated disease is a critical priority. Development of vaccines and therapeutics has been hindered by the limited understanding of basic norovirus pathogenesis and cell tropism. While macrophages, dendritic cells, B cells and stem-cell-derived enteroids can all support infection of certain noroviruses in vitro 5-7 , efforts to define in vivo norovirus cell tropism have generated conflicting results. Some studies detected infected intestinal immune cells 8-12 , other studies detected epithelial cells 13 , and still others detected immune and epithelial cells 14-16 . Major limitations of these studies are that they were performed on tissue sections from immunocompromised or germ-free hosts, chronically infected hosts where the timing of infection was unknown, or following non-biologically relevant inoculation routes. Here, we report that the dominant cellular targets of a murine norovirus inoculated orally into immunocompetent mice are macrophages, dendritic cells, B cells and T cells in the gut-associated lymphoid tissue. Importantly, we also demonstrate that a norovirus can infect T cells, a previously unrecognized target, in vitro. These findings represent the most extensive analyses to date of in vivo norovirus cell tropism in orally inoculated, immunocompetent hosts at the peak of acute infection and thus they significantly advance our basic understanding of norovirus pathogenesis.

2017 Infectious Diseases Society of America Clinical Practice Guidelines for the Diagnosis and Management of Infectious Diarrhea

These guidelines are intended for use by healthcare professionals who care for children and adults with suspected or confirmed infectious diarrhea. They are not intended to replace physician judgement regarding specific patients or clinical or public health situations. This document does not provide detailed recommendations on infection prevention and control aspects related to infectious diarrhea.

The epidemiology of Norovirus in the Middle East and North Africa (MENA) region: a systematic review

Norovirus (NoV) is considered the second leading cause of viral acute gastroenteritis (AGE). To our knowledge, there are no systematic reviews assessing the role of NoV in AGE in the Middle East and North Africa (MENA) region. Consequently, we conducted an extensive systematic literature review on articles studying NoV in the 24 countries of the MENA region during the past 15 years (2000-2015). The methods and reporting were set according to the 2015 PRISMA-P and based on the elements from the international prospective register of systematic reviews (PROSPERO). We retrieved 38 studies meeting our predefined inclusion criteria and were used to extract full data. Studies reporting on NoV were conducted in 15 out of the 24 countries of the region. The reported NoV infection rates in MENA countries ranged between 0.82% and 36.84%. The majority of studies were clinical observational studies assessing NoV rates mainly among children. Participants were recruited from in- and outpatient clinics. NoV infection was reported all year round with with peaks observed mainly during cold months. GII.4 was the predominant genotype detected in stool of participants as reported by 16 out of 25 studies (64%). Overall, there is an increasing recognition of NoV as an important causative agent of AGE across all age groups in the MENA region. Further studies are needed to assess the national and the regional burden of NoV among different age groups, its molecular diversity and seasonal variability.

Ice-associated norovirus outbreak predominantly caused by GII.17 in Taiwan, 2015

Background

On 5 March 2015, Taiwan Centers for Disease Control was notified of more than 200 students with gastroenteritis at a senior high school during excursion to Kenting. We conducted an outbreak investigation to identify the causative agent and possible vehicle of the pathogen.

Methods

We conducted a retrospective cohort study by using a structured questionnaire to interview all students for consumed food items during their stay at the resort. Students were defined as a gastroenteritis case while having vomiting or diarrhea after the breakfast on 4 March. We inspected the environment to identify possible contamination route. We collected stool or vomitus samples from ill students, food handlers and environmental specimens for bacterial culture for common enteropathogens, reverse transcription polymerase chain reaction (RT-PCR) for norovirus and enzyme-linked immunosorbent assay (ELISA) for rotavirus. Norovirus PCR-positive products were then sequenced and genotyped.

Results

Of 267 students enrolled, 144 (54%) met our case definition. Regression analysis revealed elevated risk associated with iced tea, which was made from tea powder mixed with hot water and self-made ice (risk ratio 1.54, 95% confidence interval 1.22–1.98). Ice used for beverages, water before and after water filter of the ice machine and 16 stool and vomitus samples from ill students were tested positive for norovirus; Multiple genotypes were identified including GI.2, GI.4 and GII.17. GII.17 was the predominant genotype and phylogenetic analyses showed that noroviruses identified in ice, water and human samples were clustered into the same genotypes. Environmental investigation revealed the ice was made by inadequate-filtered and un-boiled water.

Conclusions

We identified the ice made by norovirus-contaminated un-boiled water caused the outbreak and the predominant genotype was GII.17. Adequately filtered or boiled water should be strongly recommended for making ice to avoid possible contamination.

Genotypic and Epidemiological Trends of Acute Gastroenteritis Associated with Noroviruses in China from 2006 to 2016

There are periodical norovirus-associated acute gastroenteritis outbreaks around the world. This study aimed to analyze the molecular and epidemiological features of norovirus infections in China during 2006–2016. We extracted epidemiological data from 132 norovirus outbreaks and the norovirus genotyping for 1291 sequences in China over the past ten years. A total of 132 norovirus outbreaks (8133 cases) were reported in China, where the east and south regions were most affected [47.7% (63/132)]. The highest number of outbreaks occurred in 2015. A seasonal pattern has been observed, with a peak from November to the following March. Most of the outbreaks occurred in middle and primary schools, accounting for 28.8% (38/132), and 28.0% (37/132) of outbreaks, respectively. The dominant age group was 10 to 19 years old, responsible for 75.7% (933/1232) of cases. Generally, the dominant genotypes was GII, for 81.9% (1058/1291) of sequences. G II.4 was the predominant genotype in China from 2004 to 2014. However, the GII.17 became more prevalent starting in 2014. Norovirus-associated acute gastroenteritis increased sharply in recent years caused by the emergence of GII.17, but epidemiological features have not changed during 2006–2016. Vigilant surveillance should be strengthened to promptly detect any variation.

A Hospital-based Case-control Study of Diarrhea in Children in Shanghai

BACKGROUND

Prevention and control of childhood diarrhea is a global priority. We conducted a case-control study of childhood diarrhea in Shanghai.

METHODS

We prospectively recruited diarrheal children in an outpatient setting. Nondiarrheal controls were individually matched to cases. Rotavirus, norovirus and bacterial pathogens were examined. Clinical and epidemiologic data were obtained at enrollment and follow-up.

RESULTS

Potential pathogens identified in 680 diarrheal cases and 680 controls were rotavirus (19.0% vs. 1.3%), norovirus (13.4% vs. 4.7%), nontyphoidal Salmonella (9.3% vs. 1.9%), enteropathogenic Escherichia coli (8.4% vs. 6.9%) and enteroaggregative Escherichia coli (7.2% vs. 6.2%) and Campylobacter (5.1% vs. 1.2%), enterotoxigenic Escherichia coli (1.2% vs. 0.6%), enterohemorrhagic Escherichia coli (0.3% vs. 0%) and Shigella (0.15% vs. 0%), respectively. The specificity and sensitivity of fecal leukocytes >5 per high-power field for the diagnosis of bacterial diarrhea were 94.2% and 22.8%. Salmonella were susceptible to ciprofloxacin, ceftriaxone and amoxicillin-clavulanate and showed low frequency of resistance to azithromycin. Campylobacter showed low frequency of resistance to azithromycin and high frequency of resistance to ciprofloxacin. Diarrheagenic Escherichia coli was highly susceptible to ciprofloxacin and amoxicillin-clavulanate. Contact with diarrheal patients was a risk factor for rotavirus [adjusted odds ratio (aOR): 11.7], norovirus (aOR: 7.5) and Campylobacter (aOR: 27.1) infections. Mother's education was positively associated with Salmonella infection (aOR: 2.1). Good hand hygiene was protective against rotavirus (aOR: 0.6), norovirus (aOR: 0.5) and Salmonella (aOR: 0.3) infections.

CONCLUSIONS

Rotavirus, norovirus, nontyphoidal Salmonella and Campylobacter are significantly associated with diarrhea in Chinese children. Fecal leukocytes >5 per high-power field can predict bacterial diarrhea. Target prevention and appropriate treatment of diarrhea should consider the potential pathogen and resistance pattern.

Pediatric norovirus GII.4 infections in Nicaragua, 1999-2015

OBJECTIVES

Investigate clinical and epidemiological factors of pediatric GII.4 norovirus infections in children with acute gastroenteritis (AGE) in Nicaragua between 1999 and 2015.

METHODS

We retrospectively analyzed laboratory and epidemiologic data from 1,790 children≤7years with AGE from 6 hospitals in Nicaragua (n=538), and 3 community clinics (n=919) and households (n=333) in León, between 1999 and 2015. Moreover, asymptomatic children from community clinics (n=162) and households (n=105) were enrolled. Norovirus was detected by real-time PCR and genotyped by sequencing the N-terminal and shell region of the capsid gene.

RESULTS

Norovirus was found in 19% (n=338) and 12% (n=32) of children with and without AGE, respectively. In total, 20 genotypes including a tentatively new genotype were detected. Among children with AGE, the most common genotypes were GII.4 (53%), GII.14 (7%), GII.3 (6%) and GI.3 (6%). In contrast, only one (1.4%) GII.4 was found in asymptomatic children. The prevalence of GII.4 infections was significantly higher in children between 7 and 12months of age. The prevalence of GII.4 was lowest in households (38%), followed by community clinics (50%) and hospitals (75%). Several different GII.4 variants were detected and their emergence followed the global temporal trend.

CONCLUSIONS

Overall our study found the predominance of pediatric GII.4 norovirus infections in Nicaragua mostly occurring in children between 7 and 12months of age, implicating GII.4 as the main norovirus vaccine target.

Estimated reductions in hospitalizations and deaths from childhood diarrhea following implementation of rotavirus vaccination in Africa

INTRODUCTION

Rotavirus is the leading cause of hospitalizations and deaths from diarrhea. 33 African countries had introduced rotavirus vaccines by 2016. We estimate reductions in rotavirus hospitalizations and deaths for countries using rotavirus vaccination in national immunization programs and the potential of vaccine introduction across the continent. Areas covered: Regional rotavirus burden data were reviewed to calculate hospitalization rates, and applied to under-5 population to estimate baseline hospitalizations. Rotavirus mortality was based on 2013 WHO estimates. Regional pre-licensure vaccine efficacy and post-introduction vaccine effectiveness studies were used to estimate summary effectiveness, and vaccine coverage was applied to calculate prevented hospitalizations and deaths. Uncertainties around input parameters were propagated using boot-strapping simulations. In 29 African countries that introduced rotavirus vaccination prior to end 2014, 134,714 (IQR 112,321-154,654) hospitalizations and 20,986 (IQR 18,924-22,822) deaths were prevented in 2016. If all African countries had introduced rotavirus vaccines at benchmark immunization coverage, 273,619 (47%) (IQR 227,260-318,102) hospitalizations and 47,741 (39%) (IQR 42,822-52,462) deaths would have been prevented. Expert commentary: Rotavirus vaccination has substantially reduced hospitalizations and deaths in Africa; further reductions are anticipated as additional countries implement vaccination. These estimates bolster wider introduction and continued support of rotavirus vaccination programs.

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 .

Randomised controlled trial of Lactobacillus rhamnosus (LGG) versus placebo in children presenting to the emergency department with acute gastroenteritis: the PECARN probiotic study protocol

INTRODUCTION

Acute gastroenteritis (AGE) is a common and burdensome condition that affects millions of children worldwide each year. Currently available strategies are limited to symptomatic management, treatment and prevention of dehydration and infection control; no disease-modifying interventions exist. Probiotics, defined as live microorganisms beneficial to the host, have shown promise in improving AGE outcomes, but existing studies have sufficient limitations such that the use of probiotics cannot currently be recommended with confidence. Here we present the methods of a large, rigorous, randomised, double-blind placebo-controlled study to assess the effectiveness and side effect profile of Lactobacillus rhamnosus GG (LGG) (ATCC 53103) in children with AGE.

METHODS AND ANALYSIS

The study is being conducted in 10 US paediatric emergency departments (EDs) within the federally funded Pediatric Emergency Care Applied Research Network, in accordance with current SPIRIT and CONSORT statement recommendations. We will randomise 970 children presenting to participating EDs with AGE to either 5 days of treatment with LGG (10¹⁰colony-forming unit twice a day) or placebo between July 2014 to December 2017. The main outcome is the occurrence of moderate-to-severe disease over time, as defined by the Modified Vesikari Scale. We also record adverse events and side effects related to the intervention. We will conduct intention-to-treat analyses and use an enrichment design to restore the statistical power in case the presence of a subpopulation with a substantially low treatment effect is identified.

ETHICS AND DISSEMINATION

Institutional review board approval has been obtained at all sites, and data and material use agreements have been established between the participating sites. The results of the trial will be published in peer-reviewed journals. A deidentified public data set will be made available after the completion of all study procedures.

TRIAL REGISTRATION NUMBER

NCT01773967.

Surveillance of norovirus among children with diarrhea in four major hospitals in Bhutan: Replacement of GII.21 by GII.3 as a dominant genotype

Background

Diarrhea is a major cause of morbidity and mortality among Bhutanese children. The etiology of diarrhea is not well known due to the challenges of conducting routine surveillance with Bhutan’s modest research facilities. Establishing an etiology is crucial toward generating evidence that will contribute to policy discussions on a diarrheal disease control program. Our previous study, during 2010–2012, revealed that norovirus (NoV) is an important cause of diarrhea among Bhutanese children, and that GII.21 was the major genotype circulating at that time. In other countries, GII.4 is the major genotype responsible for NoV infections. In this update report, we provide new prevalence data to describe the progression of the transformation and distribution of the NoV genotype among Bhutanese children.

Methods

From June 2013 through May 2014, diarrheal stool samples were collected at one national referral hospital in Thimphu, two regional referral hospitals in the eastern and central regions, and one general hospital in the western region of Bhutan. NoV was detected by reverse transcription–polymerase chain reaction (RT–PCR), by amplifying the capsid gene. The RT–PCR results were confirmed by nucleotide sequencing of the amplicons.

Results

The proportion of NoV-positive stool samples was 23.6% (147/623), of which 76.9% were NoV GII and the remainders were NoV GI. The median age of infected children was 15.5 months, with a fairly balanced female: male ratio. NoV GII was most prevalent in the colder months (late November–mid April) and NoV GI had the highest prevalence in the summer (mid April–late September). Nucleotide sequencing was successful in 99 samples of GII strains. The most common genotypes were GII.3 (42.6%), GII.4 Sydney 2012 (15.8%), and GII.4 unassigned (11.9%). No GII.21 was found in any child in the present study. Phylogenetic analysis showed that GII.3 strains in the present study belonged to an independent cluster in lineage B. These strains shared an ancestor with those from different countries and Bhutanese strains circulating during 2010.

Conclusion

NoV remains an important cause of diarrhea among Bhutanese children. Genotype GII.3 from a single ancestor strain has spread, replacing the previously circulating GII.21. Current NoV genotypes are similar to the strains circulating worldwide but are primarily related to those in neighboring countries. NoV GII is prevalent during the cold season, while GI is prevalent during the summer. To develop a NoV infection control policy, further studies are needed.

Case-Control Assessment of the Roles of Noroviruses, Human Bocaviruses 2, 3, and 4, and Novel Polyomaviruses and Astroviruses in Acute Childhood Diarrhea

BACKGROUND

The etiology of acute childhood diarrhea often eludes identification. We used a case-control study-stool archive to determine if nucleic acid tests for established and newly identified viruses diminish our previously published 32% rate of microbiologically unexplained episodes.

METHODS

Using polymerase chain reaction, we sought to detect noroviruses GI and GII, classic and novel astroviruses, and human bocaviruses (HBoVs) 2, 3, and 4 among 178 case and 178 matched control stool samples and St. Louis and Malawi polyomaviruses among a subset of 98 case and control stool samples. We calculated adjusted odds ratios and 95% confidence intervals using conditional logistic regression.

RESULTS

Noroviruses were more common in cases (GI, 2.2%; GII, 16.9%) than in controls (GI, 0%; GII, 4.5%) (adjusted odds ratio, 5.2 [95% confidence interval, 2.5-11.3]). Astroviruses and HBoVs 2, 3, and 4 were overrepresented among the cases, although this difference was not statistically significant. Malawi polyomavirus was not associated with case status, and St. Louis polyomavirus was identified in only 1 subject (a control). When identified in cases, HBoVs 2, 3, and 4 were frequently (77%) found in conjunction with a bona fide diarrheagenic pathogen. Thirty-five (20%) case and 3 (2%) control stool samples contained more than 1 organism of interest. Overall, a bona fide or plausible pathogen was identified in 79% of the case stool samples. Preceding antibiotic use was more common among cases (adjusted odds ratio, 4.5 [95% confidence interval, 2.3-8.5]).

CONCLUSION

Noroviruses were found to cause one-third of the diarrhea cases that previously had no identified etiology. Future work should attempt to ascertain etiologic agents in the approximately one-fifth of cases without a plausible microbial cause, understand the significance of multiple agents in stools, and guide interpretation of nonculture diagnostics.

Comparison of three multiplex gastrointestinal platforms for the detection of gastroenteritis viruses

BACKGROUND

Viruses are major etiological agents of childhood gastroenteritis. In recent years, several molecular platforms for the detection of viral enteric pathogens have become available.

OBJECTIVE/STUDY DESIGN

We evaluated the performance of three multiplex platforms including Biofire's Gastrointestinal Panel (FilmArray), Luminex xTAG^® Gastrointestinal Pathogen Panel (GPP), and the TaqMan Array Card (TAC) for the detection of five gastroenteritis viruses using a coded panel of 300 archived stool samples.

RESULTS

The FilmArray detected a virus in 199 (96.1%) and the TAC in 172 (83.1%) of the 207 samples (187 samples positive for a single virus and 20 samples positive for more than one virus) whereas the GPP detected a virus in 100 (78.7%) of the 127 (97 positive for one virus and three positive for more than one virus) samples. Overall the clinical accuracy was highest for the FilmArray (98%) followed by TAC (97.2%) and GPP (96.9%). The sensitivity of the FilmArray, GPP and TAC platforms was highest for rotavirus (100%, 95.8%, and 89.6%, respectively) and lowest for adenovirus type 40/41 (97.4%, 57.9% and 68.4%). The specificity of the three platforms ranged from 95.6% (rotavirus) to 99.6% (norovirus/sapovirus) for the FilmArray, 99.6% (norovirus) to 100% (rotavirus/adenovirus) for GPP, and 98.9% (astrovirus) to 100% (rotavirus/sapovirus) for TAC.

CONCLUSION

The FilmArray demonstrated the best analytical performance followed by TAC. In recent years, the availability of multi-enteric molecular testing platforms has increased significantly and our data highlight the strengths and weaknesses of these platforms.

Detection of 23 Gastrointestinal Pathogens Among Children Who Present With Diarrhea

BACKGROUND

Diarrheal diseases are a major cause of ambulatory care visits and hospitalizations among children. Because of overlapping signs and symptoms and expensive and inefficient testing methods, the etiology of pediatric diarrhea is rarely established.

METHODS

We identified children <18 years of age who were evaluated for diarrhea at Primary Children's Hospital in Salt Lake City, Utah, between October 2010 and September 2012. Stool specimens submitted for testing were evaluated by using the FilmArray gastrointestinal diagnostic system, which is a rapid multiplex polymerase chain reaction platform that can simultaneously detect 23 bacterial, viral, and protozoal agents.

RESULTS

A pathogen was detected in 561 (52%) of 1089 diarrheal episodes. The most commonly detected pathogens included toxigenic Clostridium difficile (16%), diarrheagenic Escherichia coli (15%), norovirus GI/GII (11%), and adenovirus F 40/41 (7%). Shiga toxin-producing E coli were detected in 43 (4%) specimens. Multiple pathogens were identified in 160 (15%) specimens. Viral pathogens (norovirus, adenovirus, rotavirus, and sapovirus) were more common among children <5 years old than among those 5 to 17 years old (38% vs 16%, respectively; P < .001). Bacterial pathogens were identified most commonly in children 2 to 4 years of age. Children with 1 or more underlying chronic medical conditions were less likely to have a pathogen identified than those without a chronic medical condition (45% vs 60%, respectively; P < .01). Viral pathogens were detected more commonly in the winter, whereas bacterial pathogens were detected more commonly in the summer.

CONCLUSIONS

Toxigenic C difficile, diarrheagenic E coli, and norovirus were the leading organisms detected among these children with diarrhea. Viral pathogens are identified frequently among young children with acute gastroenteritis.

Can Use of Viral Load Improve Norovirus Clinical Diagnosis and Disease Attribution?

BACKGROUND

Real-time reverse-transcriptase polymerase chain reaction (RT-PCR) is the state-of-the-art diagnostic for norovirus. Cycle threshold (Ct), an indicator of viral load, may be associated with symptomatic disease as well as demographic and outbreak characteristics.

METHODS

Data on (1) outbreak and sporadic cases and (2) asymptomatic controls in the United States and Latin America were analyzed. With multivariate regression models, we assessed relationships between various factors and Ct values, and we calculated odds ratios (ORs) for the presence of symptoms and attributable fractions of norovirus. Receiver-operating characteristic analysis was performed to define an optimal Ct cutoff to identify disease-causing infections.

RESULTS

Cycle threshold values were lower (ie, higher viral loads) among symptomatic cases (model-adjusted mean ± standard error: 25.3 ± 1.2) compared with asymptomatic controls (28.5 ± 1.4). Cycle threshold values were significantly different across age groups, norovirus genogroups, timing of specimen collection, outbreak settings, and transmission modes. Genogroup II (GII) Ct values were associated with presence of symptoms (OR = 1.1), allowing us to estimate that 16% of diarrheal disease was attributable to norovirus. The optimized Ct cutoff led to poor sensitivity and specificity for genogroup I and GII.

CONCLUSIONS

Cycle threshold values were associated with host, pathogen, and outbreak factors. Cycle threshold values may not effectively distinguish disease-causing infection for individual patients, but they are useful for epidemiological studies aiming to attribute disease.

Right-Sizing Technology in the Era of Consumer-Driven Health Care

Technology for modern clinical and public health microbiology laboratories has evolved at an impressive rate over the last two decades. Contemporary diagnostics can rapidly provide powerful data that can impact patient lives and support infectious disease outbreak investigations. At the same time, dramatic changes to health care delivery are putting new pressures on a system that is now focusing on patient-centric, value-driven, convenient care. For laboratories, balancing all these demands in a cost-contained environment remains a challenge. This article explores the current and future directions of diagnostics in our dynamic health care environment.

Human enteroviruses associated with and without diarrhea in Thailand between 2010 and 2016

Non-bacterial acute gastroenteritis (AGE) associated with virus infection affects individuals living in developing countries, especially children. To investigate whether shedding of certain human enterovirus (EV) is more frequently detected in the stool of individuals with AGE of unknown etiology than individuals without AGE symptoms, we tested fecal samples collected from 2,692 individuals with diarrhea between January 2010 and December 2016. Samples were tested for rotavirus, norovirus, and EV by reverse-transcription polymerase chain reaction (RT-PCR) and adenovirus by PCR. EV-positive samples were subjected to sequencing and phylogenetic analysis to identify EV species and types. Findings were compared to EV found in 1,310 fecal samples from individuals without AGE who were diagnosed with hand, foot, and mouth disease (HFMD). While the majority of viruses identified in AGE consisted of human rotavirus (22.7%), norovirus (11.4%) and adenovirus (9.3%), we identified EV (6.2%) belonging mainly to species B, C, and rhinovirus. In contrast, >92% of EV found without AGE symptoms belonged to species A. Although AGE symptoms are not often attributed to EV infection, EV was associated with diarrhea of unknown etiology at least in 3.4% of AGE cases. While CV-A6 was most likely to be found in stools of HFMD patients, rhinovirus A and C were the two most common EV species associated with AGE. Elucidating group-specific EV infection in diseases with and without AGE will be useful in assisting identification, clinical management, and the surveillance of EV infection in the community.

Prospects and Challenges in the Development of a Norovirus Vaccine

PURPOSE

Norovirus is the leading cause of acute epidemic gastroenteritis among children under the age of 5 years and adults in the United States and in adults worldwide, accounting for an estimated 20% of episodes of acute gastroenteritis across all ages. No effective vaccine is presently available. This article provides an overview of the current state of norovirus vaccine development, emphasizing barriers and challenges in the development of an effective vaccine, correlates of protection used to assess vaccine efficacy, and the results of clinical trials of the major candidate vaccines.

METHODS

We performed an unstructured literature review of published articles listed in PubMed in the field of norovirus vaccine development, with an emphasis on studies in humans.

FINDINGS

Two candidate vaccines have reached clinical trials, and a number of other candidates are in the preclinical stages of development. Multivalent vaccination may be effective in inducing broadly neutralizing antibodies protective against challenge with novel and heterologous norovirus strains. Most identified correlates of protection have not been validated in large-scale challenge studies, nor have the degrees to which these correlates covary been assessed.

IMPLICATIONS

Immune correlates of protection against norovirus infection need to be further developed to facilitate additional studies of the tolerability and efficacy of candidate norovirus vaccines in humans.

Effectiveness of rotavirus vaccines against hospitalisations in Japan

BACKGROUND

In Japan, rotavirus hospitalisation occurs at a rate from 2.8 to 13.7 per 1000 child-years among children age less than 5 years, and it imposes a substantial burden to the healthcare system in the country. While both monovalent (RV1) and pentavalent (RV5) rotavirus vaccines are licensed in Japan, neither has been incorporated in the national infant immunization programme. In this study, we estimated vaccine effectiveness (VE) in Japan.

METHODS

This study was conducted in Yuri-Kumiai General Hospital located in a city in the north-western part of Japan. Age-eligible children for rotavirus vaccination were enrolled if they were hospitalized for rotavirus gastroenteritis between September 2013 and August 2016. Rotavirus gastroenteritis was defined by the detection of rotavirus antigen by immunochromatography. "Vaccinated" was defined as infant inoculated with at least one dose of either RV1 or RV5. A conditional logistic regression analysis was performed by modelling the year of birth, year of admission, residence of the children and vaccination status, and by matching the age of cases with that of test-negative controls. The adjusted odds ratio of the vaccinated over unvaccinated was then used to calculate VE in the formula of (1 - adjusted odds ratio) × 100.

RESULTS

Out of the 244 patients enrolled, rotavirus antigen was detected in 55 (22.5%) of whom 10 (18.2%) were vaccinated, whereas 94 (49.7%) of 189 test-negative controls were vaccinated. During the study period, the vaccine uptake rate in the controls increased from 36.2% to 61.8%. On the other hand, the vaccination coverage over the three years was 64.2% in Yuri-Honjo city (three quarters of the catchment), and 91.4% in Nikaho city (one quarter of the catchment). The VE was calculated to be 70.4% (95% confidence interval: 36.0-86.4%, P = 0.002). The point estimate of the VE was lower but its 95% confidence interval overlaps those of the efficacies obtained from clinical trials in Japan.

CONCLUSION

The rotavirus vaccine was effective in the real-world setting in Japan as in the clinical trials, and the introduction of rotavirus vaccine in the national infant immunization schedule will substantially reduce the number of rotavirus gastroenteritis hospitalisation in Japan.

A Luciferase Immunoprecipitation System (LIPS) assay for profiling human norovirus antibodies

A luciferase immunoprecipitation systems (LIPS) assay was developed to define the antigenic specificity and titer of antibodies directed against human norovirus (HuNoV). Recombinant proteins, expressed by plasmid constructs encoding Renilla luciferase (Ruc) fused to the full-length HuNoV major capsid protein (VP1) (Ruc-antigen), were generated for ten HuNoV strains. In addition, subdomain constructs Ruc-Shell (S) and Ruc-Protruding (P) were engineered for a representative GII.4 norovirus (strain GII.4/2006b). The LIPS assay measured antibody levels in a well-defined panel of HuNoV-specific sera, and the results were compared to an ELISA standard. In hyperimmune sera, the LIPS produced titers similar to or higher than those measured by the ELISA of HuNoV-specific antibodies. The specificity of antibodies in various sera was profiled by LIPS with a panel of diverse Ruc-antigens containing full-length HuNoV VP1 proteins or VP1 subdomains, and the assay detected both specific and cross-reactive antibodies. Competition assays, in which antibodies were pre-incubated with one or more intact VLPs representing different genotypes, proved useful in further assessment of the antibody specificity detected by LIPS in complex polyclonal sera. The profiling of HuNoV-specific antibodies in the high-throughput LIPS format may prove useful in defining the strength or specificity of the adaptive immune response following natural infection or vaccination.

Diagnostic yield of stool culture and predictive factors for positive culture in patients with diarrheal illness

We aimed to investigate the diagnostic yield of stool cultures and identify predictive factors for positive cultures in patients with diarrheal illness.A total of 13,327 patients who underwent stool cultures due to diarrheal illness were reviewed. Stool cultures were performed for enteric pathogens, including Salmonella, Shigella, Vibrio, Klebsiella oxytoca, and Yersinia. The culture-positive group was compared with the culture-negative group who were randomly selected from culture negative patients.A total of 196 patients (1.47%) were diagnosed with positive stool culture. In 196 culture positive patients, Salmonella spp. (75.0%) was detected most commonly, followed by Vibrio (19.4%). Univariate analyses showed fever (>37.8°C), vomiting, duration and frequency of diarrhea, and high C-reactive protein (CRP) were significantly associated with positive stool culture. Multivariate analysis showed fever (odds ratio [OR], 2.33; 95% confidence interval [CI], 1.25-4.35; P = .008), ≥5/day of diarrhea (OR, 3.52; 95% CI, 1.93-6.44; P < .001) and >50 mg/L of CRP (OR, 2.27; 95% CI, 1.18-4.36; P = .014) were independent predictors for positive stool culture. OR in patients with all 3 factors was 6.55 (95% CI, 2.56-16.75; P < .001). Vomiting (OR, 0.32; 95% CI, 0.17-0.57; P < .001) was a negative predictive factor.Diagnostic yield of stool culture in patients with diarrheal illness is very low. Fever, frequency of diarrhea, and high CRP are predictors for positive stool cultures. These findings may lead to more discerning and cost-effective utilization of stool culture by clinicians.

High prevalence of GII norovirus in hospitalized children with acute diarrhea, in Beijing

This study was addressed to the relationship between norovirus and acute diarrhea in hospitalized children, including hospital-acquired infection (HAI) and community-acquired infection (CAI) in a children's hospital in Beijing. RT-PCR was used to detect norovirus in stool specimen, followed by sequence analysis for PCR products. From 2010 to 2013, a total of 1248 specimens, including 661 from the HAI group and 587 from the CAI group were tested for norovirus. Norovirus were detected in 380 of 1248 (30.4%) diarrheal specimens. The positive rate for norovirus detection was higher in children within HAI group than CAI group (35.3%, 232/661 vs. 25.6%, 148/587), and the difference was significant (X² = 14.35, P<0.05). For age distribution, the highest positivity rates of norovirus were in age of 0–5 months for HAI group and 12–23 months for CAI group. In the study, 262 amplicons of the VP1 region from norovirus-positive specimens were sequenced, which showed GII.3 and GII.4 norovirus were the most common genotypes detected in 50.0% (n = 131) and 48.9% (n = 128) of the positive specimens, respectively. Regarding the wards distribution, GII.3 norovirus was mainly detected in ward for neonatal diseases (36/85 in HAI group; 19/46 in CAI group), GII.4 norovirus was mainly detected in ward for respiratory and digestive diseases (21/85 in HAI group; 15/33 in CAI group). Conclusion: The data elaborated the importance of norovirus in hospital associated infectious diarrhea. The prevalence of norovirus is higher from HAI group than CAI group, and the norovirus from the patients in CAI group could be the source of infection in HAI group.

Burden of acute gastroenteritis caused by norovirus in China: A systematic review

BACKGROUND

To understand the epidemiology and disease burden of norovirus (NoVs) gastroenteritis in China, a systematic review was conducted.

METHODS

Studies on acute gastroenteritis (AGE) caused by NoVs from mainland China, published before 2017 were searched. All retrieved articles were screened and reviewed by a standardized algorithm. NoVs detection rates as well as strain variations by ages, seasonal variations and geographic locations were analyzed using random-effects model.

RESULTS

A total of 225 articles were included in the final analysis. Similar detection rates at 21.0% and 19.8% were obtained from the North and the South, respectively. NoVs infection occurred year round, with a peak between October and January in the North and between August and November in the South. High detection rates (∼29%) of NoVs were found in adults and the elderly and in children aged 6-35 months (∼22%). The predominant strains were GII.4 (70.4%), followed by GII.3 (13.5%).

CONCLUSION

NoVs cause significant disease burden in China which warrants development of vaccines against NoVs, particularly for children and the elderly who are vulnerable to gastroenteritis diseases. To achieve a broad protection, continual monitoring NoV epidemics and strain variations for selection of proper vaccine strains is critical.

Frequency and molecular characterization of human norovirus in Erzurum, Turkey

BACKGROUND/AIM

There are limited studies on genotyping and phylogenetic analysis of norovirus in Turkey, and this has not previously been studied in the Eastern Anatolia region. The aim of the present study was to determine the norovirus profile in this region with genotyping and phylogenetic analysis.

MATERIALS AND METHODS

Included in the study were stool samples obtained from 427 people from different age groups in Eastern Anatolia. The nucleic acid samples isolated by the automatic system and nucleic acid sequence reactions and phylogenetic analyses were performed on RNA samples.

RESULTS

The presence of norovirus was detected in 86 (20.1%) of the 427 stool samples by RT-PCR analysis. Twenty-six samples selected randomly from norovirus-RNA positive samples were subjected to the sequence reaction. In 24 of the 26 samples, genogroup GII was determined, as well as one each from GI and GIV in sequence reactions. Four different genotypes were detected in genogroup GII, which were determined to be the dominant types. These were GII.1, GII.4, GII.16, and GII.21. The GI.6 and GIV.1 genotypes were determined in genogroups GI and GIV, respectively.

CONCLUSION

The high frequency and genetic diversity of these infections are risk factors for disease and so vaccine studies should be undertaken in consideration of this situation.

Correlates of protection for enteric vaccines

An immunological Correlate of Protection (CoP) is an immune response that is statistically interrelated with protection. Identification of CoPs for enteric vaccines would help design studies to improve vaccine performance of licensed vaccines in low income settings, and would facilitate the testing of future vaccines in development that might be more affordable. CoPs are lacking today for most existing and investigational enteric vaccines. In order to share the latest information on CoPs for enteric vaccines and to discuss novel approaches to correlate mucosal immune responses in humans with protection, the Foundation Mérieux organized an international conference of experts where potential CoPs for vaccines were examined using case-studies for both bacterial and viral enteric pathogens. Experts on the panel concluded that to date, all established enteric vaccine CoPs, such as those for hepatitis A, Vi typhoid and poliovirus vaccines, are based on serological immune responses even though these may poorly reflect the relevant gut immune responses or predict protective efficacy. Known CoPs for cholera, norovirus and rotavirus could be considered as acceptable for comparisons of similarly composed vaccines while more work is still needed to establish CoPs for the remaining enteric pathogens and their candidate vaccines. Novel approaches to correlate human mucosal immune responses with protection include the investigation of gut-originating antibody-secreting cells (ASCs), B memory cells and follicular helper T cells from samples of peripheral blood during their recirculation.

Genetic and Epidemiologic Trends of Norovirus Outbreaks in the United States from 2013 to 2016 Demonstrated Emergence of Novel GII.4 Recombinant Viruses

Noroviruses are the most frequent cause of epidemic acute gastroenteritis in the United States. Between September 2013 and August 2016, 2,715 genotyped norovirus outbreaks were submitted to CaliciNet. GII.4 Sydney viruses caused 58% of the outbreaks during these years. A GII.4 Sydney virus with a novel GII.P16 polymerase emerged in November 2015, causing 60% of all GII.4 outbreaks in the 2015-2016 season. Several genotypes detected were associated with more than one polymerase type, including GI.3, GII.2, GII.3, GII.4 Sydney, GII.13, and GII.17, four of which harbored GII.P16 polymerases. GII.P16 polymerase sequences associated with GII.2 and GII.4 Sydney viruses were nearly identical, suggesting common ancestry. Other common genotypes, each causing 5 to 17% of outbreaks in a season, included GI.3, GI.5, GII.2, GII.3, GII.6, GII.13, and GII.17 Kawasaki 308. Acquisition of alternative RNA polymerases by recombination is an important mechanism for norovirus evolution and a phenomenon that was shown to occur more frequently than previously recognized in the United States. Continued molecular surveillance of noroviruses, including typing of both polymerase and capsid genes, is important for monitoring emerging strains in our continued efforts to reduce the overall burden of norovirus disease.

Prevalence of Rotavirus Genogroup A and Norovirus Genogroup II in Bassaseachic Falls National Park Surface Waters in Chihuahua, Mexico

In areas lacking potable water treatment, drinking contaminated water may represent a public health threat. In addition to enteropathogenic bacteria and parasites, fecal contamination in water environments is associated with the transmission of enteric viruses and other causal agents of infectious disease. Rotavirus and norovirus are the main enteric viral agents responsible for diarrheic outbreaks. The aim of the present study was to detect seasonal variation of rotavirus and norovirus in the surface water at Bassaseachic Falls National Park during 2013. Rivers and streams within and nearby this park were sampled once in each season during 2013. Viral concentration was carried out by a handmade filtration equipment, using a commercial electropositive membrane coupled with the virus absortion elution technique (VIRADEL©). Detection of rotavirus and norovirus was performed by SYBR Green reverse transcription-real time polymerase chain reaction (SYBR GREEN© RT-qPCR) analyses. Norovirus genogroup II was detected in samples collected in June and October 2013. In the case of rotavirus, genogroup A was detected in March and June. The presence of rotavirus and norovirus was related to viral acute diarrhea in children less than five years of age, who were inhabiting the sampled areas. This may indicates that the contaminated water was potentially a risk factor for regional diarrheic outbreaks.

B-Cell Responses to Intramuscular Administration of a Bivalent Virus-Like Particle Human Norovirus Vaccine

Human noroviruses (HuNoVs) are a leading cause of acute gastroenteritis worldwide. A virus-like particle (VLP) candidate vaccine induces the production of serum histo-blood group antigen (HBGA)-blocking antibodies, the first identified correlate of protection from HuNoV gastroenteritis. Recently, virus-specific IgG memory B cells were identified to be another potential correlate of protection against HuNoV gastroenteritis. We assessed B-cell responses following intramuscular administration of a bivalent (genogroup I, genotype 1 [GI.1]/genogroup II, genotype 4 [GII.4]) VLP vaccine using protocols identical to those used to evaluate cellular immunity following experimental GI.1 HuNoV infection. The kinetics and magnitude of cellular immunity to G1.1 infection were compared to those after VLP vaccination. Intramuscular immunization with the bivalent VLP vaccine induced the production of antibody-secreting cells (ASCs) and memory B cells. ASC responses peaked at day 7 after the first dose of vaccine and returned to nearly baseline levels by day 28. Minimal increases in ASCs were seen after a second vaccine dose at day 28. Antigen-specific IgG memory B cells persisted at day 180 postvaccination for both GI.1 and GII.4 VLPs. The overall trends in B-cell responses to vaccination were similar to the trends in the responses to infection, where there was a greater bias of an ASC response toward IgA and a memory B-cell response to IgG. The magnitude of the ASC and memory B-cell responses to the GI.1 VLP component of the vaccine was also comparable to that of the responses following GI.1 infection. The production of IgG memory B cells and persistence at day 180 is a key finding and underscores the need for future studies to determine if IgG memory B cells are a correlate of protection following vaccination. (This study has been registered at ClinicalTrials.gov under registration no. NCT01168401.)

Genotype analysis of noroviruses associated with gastroenteritis outbreaks in childcare centres, Victoria, Australia, 2012-2015

The characteristics of norovirus outbreaks in children (0-5 years) in childcare centres in Victoria, Australia (2012-2015) were examined. The three most common open reading frame (ORF) 2 genotypes in childcare centre outbreaks were GII.4 (42%), GII.6 (21%) and GII.3 (14%); the remaining genotypes (GI.2, GI.3, GI.4, GI.8, GI.13, GII.1, GII.2, GII.7 and GII.13) each made up <10%. The GII.4 genotype was the only norovirus genotype seen in all 4 years of the study and was the most common genotype in 2012-2014 but in 2015 the most common genotype was GII.2. The GII.4 genotype was more common in children 0-2 years, whereas GII.2 and GII.7 were more common in children 4-5 years. ORF 1/ORF 2 recombinant forms identified were GII.P4_NewOrleans_2009/GII.4_Sydney_2012, GII.P12/GII.3, GII.Pb (GII.21)/GII.3, GII.Pe/GII.2, GII.Pe/GII.4_Sydney_2012 and GII.Pg/GII.1. The findings indicate that norovirus genotype prevalence patterns in children were influenced by the age of the children and the year in which the analysis was carried out. The majority of norovirus infections (84%) occurred after the first year of life so that vaccination before the age of one would appear to be the most efficacious.

Changes in the numbers of patients with acute gastroenteritis after voluntary introduction of the rotavirus vaccine in a Japanese children's primary emergency medical center

Background

Acute gastroenteritis (AGE) is a major reason for presentation to pediatric primary emergency medical centers. Because rotavirus vaccines were introduced in November 2011 for voluntary vaccination in Japan, we analyzed the changes in the numbers of AGE patients.

Methods

The number and proportion of patients visiting Kobe children’s primary emergency medical center from January 2011 to February 2015 due to AGE, out of all visiting children, were investigated retrospectively. The rotavirus and norovirus epidemic periods were defined as the periods from March to June and from November to February, respectively, based on their disease prevalence.

Results

In patients ≤2 years of age, the numbers and proportions of patients with AGE were significantly decreased from 2464/14098 (17%) in 2011 to 1888/12321 (15%) in 2014 (p < 0.01). In patients ≤2 and 3–5 years of age, significant decreases in AGE patients between 2011 and 2014 were observed during the rotavirus season (from 20% [1090/5329] to 14% [642/4482] in patients aged ≤2 years and from 23% [704/3047] to 20% [572/2807] in patients aged 3–5 years, p < 0.01 and p < 0.05, respectively), but not during the norovirus season (from 19% [834/4436] to 19% [797/4160] in patients aged ≤2 years and from 20% [679/3334] to 25% [710/2852] in patients aged 3–5 years).

Conclusions

The estimated rotavirus vaccine coverage in our area increased from 1% in 2011 to 49% in 2014; this coverage may have resulted in a reduction in AGE patients, both directly and indirectly, in our Japanese children’s primary emergency medical center.

Clinical Epidemiology and Treatment of Febrile and Afebrile Convulsions With Mild Gastroenteritis: A Multicenter Study

BACKGROUND

We investigated features and responses to treatment in patients with febrile and afebrile convulsions with mild gastroenteritis and characterized convulsions with rotavirus and norovirus gastroenteritis.

METHODS

We conducted a prospective, observational study to evaluate patients with febrile and afebrile convulsions with mild gastroenteritis who were hospitalized between November 2011 and March 2014 at 13 facilities in the National Hospital Organization. We classified the patients into two groups: presence or absence of fever. We investigated the background, clinical and laboratory characteristics, viral antigen in stool, and efficacy of anticonvulsant drugs.

RESULTS

Of 126 patients enrolled in this study, 50 were febrile (Fc group) and 76 were afebrile (aFc group). A family history of febrile seizures was significantly more frequent in the Fc group than in the aFc group (28.0% vs 9.2%, P = 0.005). Clinical characteristics were similar between the rotavirus and norovirus groups, but fever was significantly more frequent in the rotavirus group (46.2% vs 8.3%, P < 0.001). Serum sodium levels were significantly negatively related to the number of seizures in the aFc group (β = -0.13; 95% confidence interval, -0.24, -0.03; P = 0.01). Carbamazepine was significantly more efficacious than diazepam suppositories in the aFc group (odds ratio = 49.3, 95% confidence interval, 2.35, 1037; P = 0.01).

CONCLUSION

Febrile convulsions with mild gastroenteritis show characteristics of both febrile seizures and convulsions with mild gastroenteritis. Carbamazepine is optimal for convulsions with mild gastroenteritis. Clinical features of convulsions with rotavirus and norovirus gastroenteritis are similar, except for fever. Serum sodium levels may play a major role in the onset of convulsions with mild gastroenteritis.

Norovirus in Latin America: Systematic Review and Meta-analysis

BACKGROUND

Noroviruses are increasingly recognized as a major cause of sporadic and epidemic acute gastroenteritis (AGE). Although there have been multiple studies published on norovirus epidemiology in Latin America, no comprehensive assessment of the role of norovirus has been conducted in the region. We aim to estimate the role of norovirus in the Latin American region through a systematic review and meta-analysis of the existing literature.

METHODS

We carried out a literature search in MEDLINE, SciELO and LILACS. We included papers that provided information on the prevalence or incidence of norovirus (including seroprevalence studies and outbreaks), with a recruitment and/or follow-up period of at least 12 months and where the diagnosis of norovirus was confirmed by reverse transcription polymerase chain reaction. The data were pooled for meta-analysis to estimate the prevalence of norovirus AGE and norovirus asymptomatic infection with 95% confidence intervals (CIs).

RESULTS

Thirty-eight studies were included in the review. Overall, the prevalence of norovirus among AGE cases was 15% (95% CI: 13-18). By location, it was 15% in the community (95% CI: 11%-21%), 14% in outpatient settings (95% CI: 10%-19%) and 16% in hospital locations (95% CI: 12%-21%). The prevalence of norovirus among asymptomatic subjects was 8% (95% CI: 4-13). Norovirus GII.4 strains were associated with 37%-100% of norovirus AGE cases, but only 7% of norovirus asymptomatic detections.

CONCLUSIONS

Noroviruses are associated with almost 1 out of every 6 hospitalizations because of acute diarrhea in children younger than 5 years of age in Latin America.