Incidence of Norovirus and Other Viral Pathogens That Cause Acute Gastroenteritis (AGE) among Kaiser Permanente Member Populations in the United States, 2012-2013

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

BACKGROUND

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 amongst travellers is limited.

METHODS

Prospective, multi-site, observational cohort study conducted 2015-2017, amongst 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 whilst travelling. Post-travel stool samples were requested from symptomatic subjects and a sample of asymptomatic travellers within 14 days of return. Samples were tested for NoV by RT-qPCR, genotyped if positive and tested for other common enteric pathogens by Luminex xTAG GPP.

RESULTS

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% confidence interval (CI): 22.4; 27.1]. In total, 20 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%). In total, 80% of NoV-positive participants (vs 38.9% in NoV-negative) reported at least moderate impact on travel plans.

CONCLUSIONS

AGE is a prevalent disease amongst 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.

Prevalence of irritable bowel syndrome and functional dyspepsia after acute gastroenteritis: systematic review and meta-analysis

OBJECTIVE

Disorders of gut-brain interaction may arise after acute gastroenteritis. Data on the influence of pathogen type on the risk of postinfection IBS (PI-IBS), as on postinfection functional dyspepsia (PI-FD), are limited. We conducted a systematic review and meta-analysis to determine prevalence of PI-IBS or PI-FD after acute gastroenteritis.

DESIGN

We included observational studies recruiting ≥50 adults and reporting prevalence of IBS or FD after acute gastroenteritis with ≥3-month follow-up. A random effects model was used to estimate prevalence and ORs with 95% CIs.

RESULTS

In total, 47 studies (28 170 subjects) were eligible. Overall prevalence of PI-IBS and PI-FD were 14.5% and 12.7%, respectively. IBS persisted in 39.8% of subjects in the long-term (>5 years follow-up) after diagnosis. Individuals experiencing acute gastroenteritis had a significantly higher odds of IBS (OR 4.3) and FD (OR 3.0) than non-exposed controls. PI-IBS was most associated with parasites (prevalence 30.1%), but in only two studies, followed by bacteria (18.3%) and viruses (10.7%). In available studies, Campylobacter was associated with the highest PI-IBS prevalence (20.7%) whereas Proteobacteria and SARS-CoV-2 yielded the highest odds for PI-IBS (both OR 5.4). Prevalence of PI-FD was 10.0% for SARS-CoV-2 and 13.6% for bacteria (Enterobacteriaceae 19.4%).

CONCLUSION

In a large systematic review and meta-analysis, 14.5% of individuals experiencing acute gastroenteritis developed PI-IBS and 12.7% PI-FD, with greater than fourfold increased odds for IBS and threefold for FD. Proinflammatory microbes, including Proteobacteria and subcategories, and SARS-CoV-2, may be associated with the development of PI-IBS and PI-FD.

Prevalence of Enteric Pathogens and Antibiotic Resistance: Results of a Six-Year Active Surveillance Study on Patients Admitted to a Teaching Hospital

BACKGROUND

Acute Infectious Diarrhea (AID) and the short- and long-term complications associated with it are major causes of hospitalization worldwide. In Italy, due to a lack of robust surveillance programs, only limited data has been collected on their prevalence and circulation. This study aims to evaluate the resistance pattern of enteric pathogens and their epidemiological trends over a six-year period.

METHODS

This cross-sectional retrospective study was conducted from January 2018 to December 2023. Stool samples were analyzed during routine diagnosis with culture methods, syndromic molecular tests, and enzyme immunoassay.

RESULTS

Bacteria were the most isolated enteric pathogens (62.2%), followed by fungi (29.0%), viruses (8.2%), and parasites (0.6%). Most bacteria were isolated from outpatients (29.5%) and from patients in the Oncology ward (26.2%). The most prevalent target was EPEC (11.1%), followed by C. difficile toxin A/B-producing strains (8.3%), C. jejuni (2.5%), and S. enterica, (1%.). Norovirus and Candida spp. were the most prevalent in pediatric patients (6.5% and 39.6%, respectively). In the last years, enteric pathogens have been a frequent cause of infections characterized by a problematic resistance to common antimicrobials. In our study, S. enterica showed resistance to amikacin, gentamicin, ampicillin, levofloxacin, and ciprofloxacin. C. jejuni was susceptible to all tested drugs.

CONCLUSION

Timely notification of gastroenteric infections is crucial in identifying potential outbreak sources and ensuring strict adherence to food safety and hygiene practices, so as to protect the most vulnerable populations. The present study offers insights into the epidemiological characteristics and the antibiotic susceptibility of the main enteric AID pathogens in order to implement infection control measures in health care settings.

Trends for Syndromic Surveillance of Norovirus in Emergency Department Data Based on Chief Complaints

BACKGROUND

This study compared trends in norovirus cases to determine whether chief complaint-based emergency department (ED) visit data could reflect trends of norovirus in Korea.

METHODS

The ED visits from the National Emergency Department Information System database and the weekly reported number of noroviruses from the sentinel surveillance system were collected between August 2017 and December 2020. The correlation between weekly norovirus cases and weekly ED visits considering the chief complaint and discharge diagnosis code was estimated using a 3-week moving average.

RESULTS

In total, 6 399 774 patients with chief complaints related to digestive system disease visited an ED. A higher correlation between reported norovirus cases and ED visit with chief complaint of vomiting and discharge diagnosis code of gastroenteritis and colitis of unspecified origin or other and unspecified gastroenteritis and colitis of infectious origin was observed (R = 0.88, P < .0001). The correlation was highest for the age group 0-4 years (R = 0.89, P < .0001). However, no correlation was observed between the reported norovirus cases and the number of ED visits with norovirus identified as a discharge diagnosis code.

CONCLUSIONS

ED visit data considering a combination of chief complaints and discharged diagnosis code would be useful for early detection of infectious disease trends.

A narrative review of norovirus epidemiology, biology, and challenges to vaccine development

Norovirus is a leading cause of acute gastroenteritis (AGE) globally. AGE resulting from norovirus causes significant morbidity and mortality in countries of all income levels, particularly among young children and older adults. Prevention of norovirus AGE represents a unique challenge as the virus is genetically diverse with multiple genogroups and genotypes cocirculating globally and causing disease in humans. Variants of the GII.4 genotype are typically the most common genotype, and other genotypes cause varying amounts of disease year-to-year, with GII.2, GII.3, and GII.6 most prevalent in recent years. Noroviruses are primarily transmitted via the fecal-oral route and only a very small number of virions are required for infection, which makes outbreaks of norovirus extremely difficult to control when they occur. Settings like long-term care facilities, daycares, and hospitals are at high risk of outbreaks and can have very high attack rates resulting in substantial costs and disease burden. Severe cases of norovirus AGE are most common in vulnerable patient populations, such as infants, the elderly, and immunocompromised individuals, with available treatments limited to rehydration therapies and supportive care. To date, there are no FDA-approved norovirus vaccines; however, several candidates are currently in development. Given the substantial human and economic burden associated with norovirus AGE, a vaccine to prevent morbidity and mortality and protect vulnerable populations could have a significant impact on global public health.

Assessing the virucidal activity of essential oils against feline calicivirus, a non-enveloped virus used as surrogate of norovirus

Norovirus (NoV) causes serious gastrointestinal disease worldwide and is regarded as an important foodborne pathogen. Due the difficulties of in vitro cultivation for human NoV, alternative caliciviruses (i.e., feline calicivirus, FCV, or murine NoV) have long been used as surrogates for in vitro assessment of the efficacy of antivirals. Essential oils (EOs) are natural compounds that have displayed antimicrobial and antioxidant properties. We report in vitro the virucidal efficacy of four EOs, Melissa officinalis L. EO (MEO), Thymus vulgaris L. EO (TEO), Rosmarinus officinalis L. EO (REO), and Salvia officinalis L. EO (SEO) against FCV at different time contacts (10, 30 min, 1, 4 and 8 h). At the maximum non-cytotoxic concentration and at 10- and 100- fold concentrations over the cytotoxic threshold, the EOs did not decrease significantly FCV viral titers. However, MEO at 12,302.70 μg/mL exhibited a significant efficacy decreasing the viral titer by 0.75 log10 Tissue Culture Infectious Dose (TCID50)/50 μl after 10 min as compared to virus control. In this study, virucidal activity of four EOs against FCV, was investigated. A lack of virucidal efficacy of TEO, REO and SEO at different compound concentrations and time contacts against FCV was observed whilst MEO was able to significantly decrease FCV titer.

Detection and Characterization of Bacterial and Viral Acute Gastroenteritis among Outpatient Children under 5 Years Old in Guangzhou, China

Acute gastroenteritis (AGE) in children can be attributed to a multitude of bacterial and viral pathogens. The objective of this study was to investigate the epidemiology of bacterial and viral AGE in children and to compare clinical characteristics between single and multiple enteric pathogen infections. A total of 456 stool samples were collected from outpatient children under 5 years old with AGE, which were subsequently analyzed for nine bacteria and three viruses using the Luminex xTAG® Gastrointestinal Pathogen Panel. The presence of at least one pathogen was detected in 260 cases (57.0%), with Salmonella being the predominant agent, followed by norovirus, Campylobacter, and rotavirus. A total of 69 cases (15.1%) exhibited positive results for two or more enteric pathogens. Although certain co-infections demonstrated significant differences in primary clinical features compared with mono-infections, no statistical variance was observed in terms of disease severity. In outpatient children from southern China, Salmonella emerged as the most prevalent causative agent of AGE, succeeded by norovirus and Campylobacter. This study underscores the burden posed by coinfections and highlights the clinical characteristics associated with AGE when accompanied by coinfections among children under 5 years old.

Viral gastroenteritis

Since the discovery of norovirus in 1972 as a cause of what was contemporarily known as acute infectious non-bacterial gastroenteritis, scientific understanding of the viral gastroenteritides has continued to evolve. It is now recognised that a small number of viruses are the predominant cause of acute gastroenteritis worldwide, in both high-income and low-income settings. Although treatment is still largely restricted to the replacement of fluid and electrolytes, improved diagnostics have allowed attribution of illness, enabling both targeted treatment of individual patients and prioritisation of interventions for populations worldwide. Questions remain regarding specific genetic and immunological factors underlying host susceptibility, and the optimal clinical management of patients who are susceptible to severe or prolonged manifestations of disease. Meanwhile, the worldwide implementation of rotavirus vaccines has led to substantial reductions in morbidity and mortality, and spurred interest in vaccine development to diminish the impact of the most prevalent viruses that are implicated in this syndrome.

Prevalence of astrovirus and sapovirus among adult oncology patients with acute gastroenteritis using a multiplexed gastrointestinal pathogen PCR panel

BACKGROUND

Multiplex syndromic gastrointestinal panels (GIPCR) have streamlined the diagnosis of infectious diarrhea. Additionally, they have expanded the number of pathogens that can be routinely evaluated, allowing further understanding of the prevalence of enteric pathogens in various patient populations. The goal of this study was to investigate the prevalence and clinical presentation of astrovirus and sapovirus gastroenteritis in adult oncology patients as detected by the FilmArray GIPCR.

METHODS

All GIPCR panel results from December 2017 to June 2021 were retrospectively reviewed to determine the prevalence of astrovirus and sapovirus in adult oncology patients. Medical records were also reviewed to obtain clinical information. Repeat GIPCR positivity and symptom duration were used to estimate prolonged viral shedding.

RESULTS

A total of 18,014 panels were performed on samples collected from 9303 adults. Overall, astrovirus and sapovirus were detected in 0.35% (33/9303) and 0.45% (42/9303) GIPCRs respectively. At least one viral target was detected in 424 (4.4%) patients. Astrovirus accounted for 7.8% (33/424) and sapovirus 9.9% (42/424) of patients. Diarrhea was the most common symptom documented. A subset of transplant patients had protracted viral detection with a median of ~27 days (range 23-43 days) for astrovirus and 97 days (range 11-495) for sapovirus. No clusters or outbreaks were identified during the study period.

CONCLUSION

In oncology patients with viral gastroenteritis, astrovirus and sapovirus were the causative agents in 18% of the cases. Both viruses were associated with mild disease. Prolonged diarrhea and viral shedding were observed in a few transplant patients.

Serological surveillance of GI norovirus reveals persistence of blockade antibody in a Jidong community-based prospective cohort, 2014-2018

Introduction

Herd immunity against norovirus (NoV) is poorly understood in terms of its serological properties and vaccine designs. The precise neutralizing serological features of genotype I (GI) NoV have not been studied.

Methods

To expand insights on vaccine design and herd immunity of NoVs, seroprevalence and seroincidence of NoV genotypes GI.2, GI.3, and GI.9 were determined using blockade antibodies based on a 5-year longitudinal serosurveillance among 449 residents in Jidong community.

Results

Correlation between human histo-blood group antigens (HBGAs) and GI NoV, and dynamic and persistency of antibodies were also analyzed. Seroprevalence of GI.2, GI.3, and GI.9 NoV were 15.1%-18.0%, 35.0%-38.8%, and 17.6%-22.0%; seroincidences were 10.0, 21.0, and 11.0 per 100.0 person-year from 2014 to 2018, respectively. Blockade antibodies positive to GI.2 and GI.3 NoV were significantly associated with HBGA phenotypes, including blood types A, B (excluding GI.3), and O+; Lewis phenotypes Leb+/Ley+ and Lea+b+/Lex+y+; and secretors. The overall decay rate of anti-GI.2 antibody was -5.9%/year (95% CI: -7.1% to -4.8%/year), which was significantly faster than that of GI.3 [-3.6%/year (95% CI: -4.6% to -2.6%/year)] and GI.9 strains [-4.0%/year (95% CI: -4.7% to -3.3%/year)]. The duration of anti-GI.2, GI.3, and GI.9 NoV antibodies estimated by generalized linear model (GLM) was approximately 2.3, 4.2, and 4.8 years, respectively.

Discussion

In conclusion, enhanced community surveillance of GI NoV is needed, and even one-shot vaccine may provide coast-efficient health benefits against GI NoV infection.

Worldwide prevalence and genotype distribution of human astrovirus in gastroenteritis patients: A systematic review and meta-analysis

AIM

Human astrovirus (HAstV) is an important causative agent of gastroenteritis in humans, which mainly infects young children and the elderly. The goal of this study was to conduct a meta-analytic review of the prevalence of HAstV amongst patients with gastroenteritis, and to shed light on the connection between HAstV infection and gastroenteritis.

METHODS

Systematic literature searches were conducted to identify all potentially relevant studies recorded up to April 8th, 2022. For study weighting, the inverse variance method was employed and the random-effects model was applied to evaluate data. For case-control studies, the pooled odds ratio (OR) and 95% confidence interval (CI) were calculated to establish the relationship between HAstV infection and gastroenteritis.

RESULTS

Among 302423 gastroenteritis patients from 69 different countries, the overall pooled prevalence of HAstV infection was 3.48% (95% CI: 3.11%-3.89%). Case-control approach was used in 39 investigations, and the overall prevalence of HAstV infection among the 11342 healthy controls was 2.01% (95% CI: 1.40%-2.89%). Gastroenteritis and HAstV infection were associated with a pooled OR of 2.16 (95% CI: 1.72-2.71; P < 0.0001; I² = 33.7%). The most commonly found HAstV genotypes in gastroenteritis patients were HAstV1 (62.18%), HAstV7 (33.33%), and HAstV-MLB1 (17.43%).

CONCLUSION

The frequency of HAstV infection was the highest in children under the age of five, and in developing countries. The prevalence rate of HAstV was not influenced by gender. Semi-nested and nested RT-PCR were highly sensitive assays for detecting HAstV infections.

Age-associated features of norovirus infection analysed in mice

Norovirus (NoV) is the leading global cause of viral gastroenteritis. Young children bear the highest burden of disease and play a key role in viral transmission throughout the population. However, which host factors contribute to age-associated variability in NoV severity and shedding are not well-defined. The murine NoV (MNoV) strain CR6 causes persistent infection in adult mice and targets intestinal tuft cells. Here we find that natural transmission of CR6 from infected dams occurred only in juvenile mice. Direct oral CR6 inoculation of wild-type neonatal mice led to accumulation of viral RNA in the ileum and prolonged shedding in the stool that was replication-independent. This viral exposure induced both innate and adaptive immune responses including interferon-stimulated gene expression and MNoV-specific antibody responses. Interestingly, viral uptake depended on passive ileal absorption of luminal virus, a process blocked by cortisone acetate administration, which prevented ileal viral RNA accumulation. Neonates lacking interferon signalling in haematopoietic cells were susceptible to productive infection, viral dissemination and lethality, which depended on the canonical MNoV receptor CD300LF. Together, our findings reveal developmentally associated aspects of persistent MNoV infection, including distinct tissue and cellular tropism, mechanisms of interferon regulation and severity of infection in the absence of interferon signalling. These emphasize the importance of defining viral pathogenesis phenotypes across the developmental spectrum and highlight passive viral uptake as an important contributor to enteric infections in early life.

Epidemiological investigations of diarrhea in children in Praia city, Cape Verde

Introduction

Diarrheal disease is a major cause of infant mortality and morbidity in Africa and results primarily from contaminated food and water sources, but its prevalence predictors in Cape Verde are not completely known. For this reason, this study aimed to identify the etiological agents of diarrhea in Cape Verdean children and assess its associated risk factors.

Methods

A survey questionnaire was used, and a total of 105 stool samples from children with diarrhea aged 0-12 years at the Central Hospital of Praia (Santiago, Cape Verde) were analyzed. The analyses were carried out using Biofire FilmArray Gastrointestinal Panels. Possible risk factors for these pathogens were analyzed using logistic regression, chi-square tests, or Fisher's exact test.

Results

Among the bacteria, enteroaggregative Escherichia coli (45.71%; 95% CI: 36.71-56.70), enteropathogenic E. coli (40%; 95% CI: 30.56-50.02), Shigella/enteroinvasive E. coli (29.52%; 95% CI: 21.02-39.22), E. coli enterotoxigenic (12.38%; 95% CI: 6.76-20.24), Campylobacter sp. (10.48%; 95% CI: 5.35-1.97), Vibrio sp. (4.76%; 95% CI: 1.56-10.76), Clostridioides difficile (3.81%; 95% CI: 1.05-9.47), Vibrio cholerae (2.86%; 0.59-8.12), Shiga-like toxin-producing E. coli (2.86%; 0.59-8.12) and Salmonella sp. (0.95%; 0.02-5.19) were identified; four viruses, Rotavirus A (28.57%; 95% CI: 20.18-38.21), Sapovirus I. II. IV and V (11.43%; 95% CI: 6.05-19.11), Norovirus GI.GII (6.67%; 95% CI: 2.72-13.25) and Adenovirus F 40.41 (6.67%; 95% CI: 2.72-13.25) were also observed. All the pathogens detected in this study were found in coinfections. Significant associations with risk factors were found; specifically, having a bathroom at home reduced the risk of Campylobacter sp., having animals at home increased the risk of Shigella/EIEC infection, and drinking bottled water reduced the risk of Sapovirus infection.

Discussion

From the findings of this study, it can be concluded that, in Cape Verde, there is a high prevalence and diversity of pathogens among children. Our results could help to establish an adequate diagnosis and effective treatments for diarrheal disease.

Incidence, Etiology, and Healthcare Utilization for Acute Gastroenteritis in the Community, United States

Knowledge of the epidemiology of sporadic acute gastroenteritis (AGE) in the United States is limited. During September 2016–September 2017, we surveyed Kaiser Permanente Northwest members in Oregon and Washington, USA, to collect data on the 30-day prevalence of dually defined AGE and diarrhea disease and related health-seeking behavior; from a subset of participants, we obtained a stool specimen. Using the iterative proportional fitting algorithm with raked weights, we generated AGE prevalence and annualized rate estimates. We detected norovirus, rotavirus, astrovirus, and sapovirus from submitted stool specimens through real-time quantitative reverse transcription PCR (qRT-PCR). We estimated a 30-day prevalence of 10.4% for AGE and 7.6% for diarrhea only; annual rates were 1.27 cases/person/year for AGE and 0.92 cases/person/year for diarrhea only. Of those with AGE, 19% sought medical care. Almost one quarter (22.4%) of stool specimens from those reporting AGE tested positive for ≥1 viral pathogen, compared with 8.2% from those without AGE.

The burden of rotavirus-associated acute gastroenteritis in the elderly: assessment of the epidemiology in the context of universal childhood vaccination programs

INTRODUCTION

Rotaviruses (RVs) cause acute gastroenteritis (AGE) in infants and young children worldwide and also in older adults (≥60 years), however the burden among this age group is not well understood. Herd immunity through pediatric RV vaccination may reduce the burden of RVGE across all ages, however the impact of pediatric vaccination on burden in older adults is poorly understood.

AREAS COVERED

This systematic review was undertaken to identify studies related to the following objectives: understand the burden of RV in older adults, RV seroprevalence, and the impact of pediatric vaccination on this burden and highlight evidence gaps to guide future research. Of studies identified, 59 studies from two databases were included in this analysis following a review by two reviewers.

EXPERT OPINION

RV is an understudied disease in older adults. We found that 0-62% of patients with AGE tested positive for RV, with results varying by setting, country, and patient age. Results also suggest that pediatric vaccination benefits older adults through herd protection. Several studies showed a reduction in RV incidence after vaccination. However, there was variety in results and lack of consistency in outcomes reported. Further studies targeting older adults are needed to better characterize RV burden.

Clinical significance and intestinal microbiota composition in immunocompromised children with norovirus gastroenteritis

Background

Norovirus (NoV) infection is common in pediatric patients with immunodeficiency and is more likely to cause severe disease. Objective Our study aims to figure out the clinical differences and distribution of intestinal microbiota in immunocompromised children with NoV gastroenteritis.

Methods

Pediatric patients admitted to Shang-Ho Hospital with diagnosis of acute gastroenteritis including different immune status were enrolled and their medical records were reviewed. NoV gastroenteritis was validated using RT-PCR molecular methods. Viral shedding period was determined by real-time RT-PCR assays. Intestinal microbiota enrichment analysis was carried out by next generation sequencing after fecal DNA extraction and subsequent Linear Discriminant Analysis (LDA) Effect Size (LEfSe) method.

Results

Significantly higher frequency of diarrhea [mean, (IQR), 3.8 (3–5) /day] and longer viral shedding time [mean, IQR, 8.5 (5–13) days] was found in immunocompromised NoV infections than in immunocompetent patients without NoV infections (p = 0.013*) and immunocompetent patients with NoV infections (p = 0.030**). The fever prevalence was significantly lower in immunocompromised NoV infections than in different immune or infection status. Intestinal microbiota metagenomics analysis showed no significant community richness difference while the LEfSe analysis showed a significant difference in commensal richness at the phylum level, the family level, and the genus level in patients under different immune status.

Conclusion

We evaluated the clinical significances and microbiota composition in immunocompromised children with norovirus gastroenteritis. This will further facilitate studies of the interaction between the intestinal microbiota in such patients with precise determination of their bacterial infection control and probiotic supplements strategy.

Multiplex PCR Pathogen Detection in Acute Gastroenteritis Among Hospitalized US Children Compared With Healthy Controls During 2011-2016 in the Post-Rotavirus Vaccine Era

Background

Despite vaccine-induced decreases in US rotavirus (RV) disease, acute gastroenteritis (AGE) remains relatively common. We evaluated AGE pathogen distribution in hospitalized US children in the post–RV vaccine era.

Methods

From December 2011 to June 2016, the New Vaccine Surveillance Network (NVSN) conducted prospective, active, population-based surveillance in hospitalized children with AGE. We tested stools from 2 NVSN sites (Kansas City, Houston) with Luminex x-TAG Gastrointestinal Pathogen Panels (Luminex GPP) and analyzed selected signs and symptoms.

Results

For 660 pediatric AGE inpatients and 624 age-matched healthy controls (HCs), overall organism detection was 51.2% and 20.6%, respectively (P < .001). Among AGE subjects, GPP polymerase chain reaction detected >1 virus in 39% and >1 bacterium in 14% of specimens. Detection frequencies for AGE subjects vs HCs were norovirus (NoV) 18.5% vs 6.6%, RV 16.1% vs 9.8%, adenovirus 7.7% vs 1.4%, Shigella 4.8% vs 1.0%, Salmonella 3.1% vs 0.1%, and Clostridioides difficile in ≥2-year-olds 4.4% vs 2.4%. More co-detections occurred among AGE patients (37/660, 5.6%) than HCs (14/624, 2.2%; P = .0024). Per logistic regression analysis, ill contacts increased risk for NoV, RV, and Shigella (P < .001). More vomiting episodes occurred with NoV and RV, and more diarrheal episodes with Shigella and Salmonella. Modified Vesikari scores were highest for Shigella and lowest for C. difficile.

Conclusions

NoV detection was most frequent; however, RV remained important in hospitalized AGE in the post–RV vaccine era. Continued active surveillance is important to document ongoing vaccine effects, pathogen emergence, and baseline disease burden for new vaccines.

Recreational water exposure and waterborne infections in a prospective salivary antibody study at a Lake Michigan beach

In a prospective observational study, seroconversion to a specific pathogen can serve as a marker of an incident infection, whether or not that infection is symptomatic or clinically diagnosed. While self-reported symptoms can be affected by reporting bias, seroconversion is likely to be free of this bias as it is based on objective measurements of antibody response. Non-invasive salivary antibody tests can be used instead of serum tests to detect seroconversions in prospective studies. In the present study, individuals and families were recruited at a Lake Michigan beach in Wisconsin in August 2011. Data on recreational water exposure and baseline saliva samples (S1) were collected at recruitment. Follow-up data on gastrointestinal symptoms were collected via a telephone interview approximately 10 days post-recruitment. Follow-up saliva samples were self-collected approximately 2 weeks (S2) and 30–40 days post-recruitment (S3) and mailed to the study laboratory. Samples were analyzed for immunoglobulin (Ig) G responses to recombinant antigens of three noroviruses and Cryptosporidium, as well as protein purification tags as internal controls, using an in-house multiplex suspension immunoassay on the Luminex platform. Responses were defined as ratios of antibody reactivities with a target protein and its purification tag. Seroconversions were defined as at least four-fold and three-fold increases in responses in S2 and S3 samples compared to S1, respectively. In addition, an S2 response had to be above the upper 90% one-sided prediction limit of a corresponding spline function of age. Among 872 study participants, there were seven (0.8%) individuals with seroconversions, including six individuals with seroconversions to noroviruses and two to Cryptosporidium (one individual seroconverted to both pathogens). Among 176 (20%) individuals who reported swallowing lake water, there were six (3.4%) seroconversions compared to one (0.14%) seroconversion among the remaining 696 individuals: the crude and age-standardized risk differences per 1000 beachgoers were 32.7 (95% confidence limits 5.7; 59.6) and 94.8 (4.6; 276), respectively. The age-adjusted odds ratio of seroconversion in those who swallowed water vs. all others was 49.5 (4.5; 549), p = 0.001. Individuals with a norovirus seroconversion were more likely to experience vomiting symptoms within 4 days of the index beach visit than non-converters with an odds ratio of 34 (3.4, 350), p = 0.003. This study contributed further evidence that recreational water exposure is associated with symptomatic and asymptomatic waterborne infections, and that salivary antibody assays can be used in epidemiological surveys of norovirus and Cryptosporidium infections.

Serological Humoral Immunity Following Natural Infection of Children with High Burden Gastrointestinal Viruses

Acute gastroenteritis (AGE) is a major cause of morbidity and mortality worldwide, resulting in an estimated 440,571 deaths of children under age 5 annually. Rotavirus, norovirus, and sapovirus are leading causes of childhood AGE. A successful rotavirus vaccine has reduced rotavirus hospitalizations by more than 50%. Using rotavirus as a guide, elucidating the determinants, breath, and duration of serological antibody immunity to AGE viruses, as well as host genetic factors that define susceptibility is essential for informing development of future vaccines and improving current vaccine candidates. Here, we summarize the current knowledge of disease burden and serological antibody immunity following natural infection to inform further vaccine development for these three high-burden viruses.

Global molecular prevalence and genotype distribution of Sapovirus in children with gastrointestinal complications: A systematic review and meta-analysis

Sapovirus (SaV) is an emerging cause of children gastrointestinal complications such as acute gastroenteritis (AGE). The aim of the present systematic review and meta-analysis was to estimate the global prevalence of the SaV in children and association of infection with SaVs and AGE in children based on case-control studies. Four international databases (PubMed, Scopus, Web of Sciences and Google Scholar) were used to retrieve English-language studies published between January 2000 and December 2020. Comprehensive Meta-Analysis software was applied to estimate the overall prevalence, publication bias and heterogeneity index. The pooled prevalence of SaV infection among children with gastroenteritis was 3.4% [95% confidence interval (CI): 2.9%-3.9%] based on a random-effects meta-analysis. Genogroup I was the dominant genogroup of SaV in children with gastroenteritis [2.2% (95% CI: 1.6%-3.0%)], association analysis showed that SaV was associated with gastroenteritis [OR: 1.843 (95% CI: 1.27-2.66)]. Given the significant prevalence of the virus in children, it is necessary to pay more attention to this situation. Therefore, preventive health measures in children should be a priority.

Development and Application of a Novel Rapid and Throughput Method for Broad-Spectrum Anti-Foodborne Norovirus Antibody Testing

Foodbone norovirus (NoV) is the leading cause of acute gastroenteritis worldwide. Candidate vaccines are being developed, however, no licensed vaccines are currently available for managing NoV infections. Screening for stimulated antibodies with broad-spectrum binding activities can be performed for the development of NoV polyvalent vaccines. In this study, we aimed to develop an indirect enzyme-linked immunosorbent assay (ELISA) for testing the broad spectrum of anti-NoV antibodies. Capsid P proteins from 28 representative NoV strains (GI.1–GI.9 and GII.1–GII.22 except GII.11, GII.18, and GII.19) were selected, prepared, and used as coating antigens on one microplate. Combined with incubation and the horseradish peroxidase chromogenic reaction, the entire process for testing the spectrum of unknown antibodies required 2 h for completion. The intra-assay and inter-assay coefficients of variation were less than 10%. The new method was successfully performed with monoclonal antibodies and polyclonal antibodies induced by multiple antigens. In conclusion, the indirect ELISA assay developed in this study had a good performance of reliability, convenience, and high-throughput screening for broad-spectrum antibodies.

Estimating the Number of Illnesses Caused by Agents Transmitted Commonly Through Food: A Scoping Review

Estimates of the overall human health impact of agents transmitted commonly through food complement surveillance and help guide food safety interventions and regulatory initiatives. The purpose of this scoping review was to summarize the methods and reporting practices used in studies that estimate the total number of illnesses caused by these agents. We identified and included 43 studies published from January 1, 1995, to December 31, 2019, by searching PubMed and screening selected articles for other relevant publications. Selected articles presented original estimates of the number of illnesses caused by ≥1 agent transmitted commonly through food. The number of agents (species or subspecies for pathogens) included in each study ranged from 1 to 31 (median: 4.5; mean: 9.2). Of the 40 agents assessed across the 43 studies, the most common agent was Salmonella (36; 84% of studies), followed by Campylobacter (33; 77%), Shiga toxin-producing Escherichia coli (25; 58%), and norovirus (20; 47%). Investigators used a variety of data sources and methods that could be grouped into four distinct estimation approaches-direct, surveillance data scaled-up, syndrome or population scaled-down, and inferred. Based on our review, we propose four recommendations to improve the interpretability, comparability, and reproducibility of studies that estimate the number of illnesses caused by agents transmitted commonly through food. These include providing an assessment of statistical and nonstatistical uncertainty, providing a ranking of estimates by agent, including uncertainties; describing the rationale used to select agents and data sources; and publishing raw data and models, along with clear, detailed methods. These recommendations could lead to better decision-making about food safety policies. Although these recommendations have been made in the context of illness estimation for agents transmitted commonly through food, they also apply to estimates of other health outcomes and conditions.

Prevalence of rotavirus among older children and adults with diarrhea: A systematic review and meta-analysis

BACKGROUND

Older children and adults are susceptible to rotavirus, but the extent to which rotavirus affects this population is not fully understood, hindering accuracy of global rotavirus estimations.

OBJECTIVE

To determine what proportion of diarrhea cases are due to rotavirus among persons ≥ 5 years old and to estimate this proportion by age strata.

METHODS

We conducted a systematic review and meta-analysis using the PRISMA guidelines. We included studies that reported on conditional rotavirus prevalence (i.e., percent of diarrhea due to rotavirus) in persons ≥ 5 years old who were symptomatic with diarrhea/gastroenteritis and had laboratory confirmation for rotavirus infection. Studies on nosocomial infections and outbreak investigations were excluded. We collected age group-specific conditional rotavirus prevalence and other variables, such as study geography, study setting, and study type. We calculated pooled conditional rotavirus prevalence, corresponding 95% confidence intervals (95% CI), heterogeneity (I²) estimates, and prediction intervals (PI).

RESULTS

Sixty-six studies from 32 countries met the inclusion criteria. Conditional rotavirus prevalence ranged from 0% to 30% across the studies. The total pooled prevalence of rotavirus among persons ≥ 5 years old with diarrhea was 7.6% (95% CI: 6.2-9.2%, I² = 99.6%, PI: 0-24%). The pooled prevalence of rotavirus among older children and adolescents was 8.7% (95% CI: 6.2-11.7%, I² = 96%, PI:0-27%), among younger adults was 5.4% (95% CI: 1.4-11.8%, I² = 96%, PI:0-31%), and among older adults was 4.7% (95% CI: 2.8-7.0%, I² = 96%, PI:0-16%). Pooled conditional rotavirus prevalences did not differ by other variables.

CONCLUSION

In this systematic review and meta-analysis of rotavirus among persons ≥ 5 years old with diarrhea, we found relatively low pooled conditional rotavirus prevalence compared to what is typically reported for children < 5 years; however, results should be interpreted with caution as the wide prediction intervals suggest large heterogeneity.

Burden of Norovirus in the United States, as Estimated Based on Administrative Data: Updates for Medically Attended Illness and Mortality, 2001-2015

BACKGROUND

Up-to-date estimates of the burden of norovirus, a leading cause of acute gastroenteritis (AGE) in the United States, are needed to assess the potential value of norovirus vaccines in development. We aimed to estimate the rates, annual counts, and healthcare charges of norovirus-associated ambulatory clinic encounters, emergency department (ED) visits, hospitalizations, and deaths in the United States.

METHODS

We analyzed administrative data on AGE outcomes from 1 July 2001 through 30 June 2015. Data were sourced from IBM MarketScan Commercial and Medicare Supplemental Databases (ambulatory clinic and ED visits), the Healthcare Utilization Project National Inpatient Sample (hospitalizations), and the National Center for Health Statistics multiple-cause-of-mortality data (deaths). Outcome data (ambulatory clinic and ED visits, hospitalizations, or deaths) were summarized by month, age group, and setting. Healthcare charges were estimated based on insurance claims. Monthly counts of cause-unspecified gastroenteritis-associated outcomes were modeled as functions of cause-specified outcomes, and model residuals were analyzed to estimate norovirus-associated outcomes. Healthcare charges were estimated by applying average charges per cause-unspecified gastroenteritis encounter to the estimated number of norovirus encounters.

RESULTS

We estimate 900 deaths (95% confidence interval [CI], 650-1100), 109 000 hospitalizations (95% CI, 80 000-145 000), 465 000 ED visits (95% CI, 348 000-610 000), and 2.3 million ambulatory clinic encounters (95% CI, 1.7-2.9 million) annually due to norovirus, with an associated $430-$740 million in healthcare charges.

CONCLUSIONS

Norovirus causes a substantial health burden in the United States each year, and an effective vaccine could have important public health impact.

The burden of norovirus disease in children: a multi-country study in Chile, Brazil, Thailand and the Philippines

BACKGROUND

Noroviruses (NoVs) cause acute gastroenteritis (AGE) worldwide, affecting children in particular. We aimed to estimate the burden of disease due to NoV among children aged <6 years in Brazil, Chile, Philippines and Thailand.

METHODS

This was a prospective, hospital-based, observational study. Children were recruited over one year between 2014 and 2017. Four cohorts were analysed: community-acquired AGE outpatients and inpatients, nosocomial AGE inpatients, and asymptomatic outpatients. We collected demographic and clinical data, and a stool sample that was tested for NoV. Positive samples were tested for Rotavirus (RV) and NoV-genotyped. Disease severity was assessed by the Vesikari and modified Vesikari scores. Prevalence and incidence of NoV-AGE were estimated by cohort and country.

RESULTS

1637 participants yielded valid laboratory results. The proportion of NoV-positive cases was 23.8% (95% CI 20.8-27.2) in the outpatient cohort, 17.9% (15.0-21.3) in the hospital cohort, 21.4% (12.7-33.8) in the nosocomial cohort and 9.6% (6.9-13.2) in the asymptomatic cohort. Genotype GII.4 was predominant (58%). Less than 4% samples had RV coinfection. In general, NoV-positive subjects had more severe presentations than NoV-negative subjects.

CONCLUSIONS

NoV caused AGE with substantial burden throughout the studied settings, with higher relative frequency in Brazil where RV vaccination coverage is high.

Estimate of Burden and Direct Healthcare Cost of Infectious Waterborne Disease in the United States

Provision of safe drinking water in the United States is a great public health achievement. However, new waterborne disease challenges have emerged (e.g., aging infrastructure, chlorine-tolerant and biofilm-related pathogens, increased recreational water use). Comprehensive estimates of the health burden for all water exposure routes (ingestion, contact, inhalation) and sources (drinking, recreational, environmental) are needed. We estimated total illnesses, emergency department (ED) visits, hospitalizations, deaths, and direct healthcare costs for 17 waterborne infectious diseases. About 7.15 million waterborne illnesses occur annually (95% credible interval [CrI] 3.88 million–12.0 million), results in 601,000 ED visits (95% CrI 364,000–866,000), 118,000 hospitalizations (95% CrI 86,800–150,000), and 6,630 deaths (95% CrI 4,520–8,870) and incurring US $3.33 billion (95% CrI 1.37 billion–8.77 billion) in direct healthcare costs. Otitis externa and norovirus infection were the most common illnesses. Most hospitalizations and deaths were caused by biofilm-associated pathogens (nontuberculous mycobacteria, Pseudomonas, Legionella), costing US $2.39 billion annually.

Sapovirus: an emerging cause of childhood diarrhea

PURPOSE OF REVIEW

Sapovirus, a genus in the Caliciviridae family alongside norovirus, is increasingly recognized as an important cause of childhood diarrhea. Some challenges exist in our ability to better understand sapovirus infections, including the inability to grow sapovirus in cell culture, which has hindered diagnosis and studies of immunity. Another challenge is that individuals with sapovirus infection are commonly coinfected with other enteric pathogens, complicating our ability to attribute the diarrhea episode to a single pathogen.

RECENT FINDINGS

Development of molecular methods for sapovirus detection has increased our ability to measure disease prevalence. The prevalence of sapovirus varies between 1 and 17% of diarrhea episodes worldwide, with the highest burden in young children and older adults. Further, epidemiological studies have used novel approaches to account for the presence of coinfections with other enteric pathogens; one multisite cohort study of children under two years of age found that sapovirus had the second-highest attributable incidence among all diarrheal pathogens studied.

SUMMARY

Especially in settings where rotavirus vaccines have been introduced, efforts to reduce the overall burden of childhood diarrhea should focus on the reduction of sapovirus transmission and disease burden.

The Clinical and Economic Burden of Norovirus Gastroenteritis in the United States

BACKGROUND

Although norovirus outbreaks periodically make headlines, it is unclear how much attention norovirus may receive otherwise. A better understanding of the burden could help determine how to prioritize norovirus prevention and control.

METHODS

We developed a computational simulation model to quantify the clinical and economic burden of norovirus in the United States.

RESULTS

A symptomatic case generated $48 in direct medical costs, $416 in productivity losses ($464 total). The median yearly cost of outbreaks was $7.6 million (range across years, $7.5-$8.2 million) in direct medical costs, and $165.3 million ($161.1-$176.4 million) in productivity losses ($173.5 million total). Sporadic illnesses in the community (incidence, 10-150/1000 population) resulted in 14 118-211 705 hospitalizations, 8.2-122.9 million missed school/work days, $0.2-$2.3 billion in direct medical costs, and $1.4-$20.7 billion in productivity losses ($1.5-$23.1 billion total). The total cost was $10.6 billion based on the current incidence estimate (68.9/1000).

CONCLUSION

Our study quantified norovirus' burden. Of the total burden, sporadic cases constituted >90% (thus, annual burden may vary depending on incidence) and productivity losses represented 89%. More than half the economic burden is in adults ≥45, more than half occurs in winter months, and >90% of outbreak costs are due to person-to-person transmission, offering insights into where and when prevention/control efforts may yield returns.

Cost-effectiveness of pediatric norovirus vaccination in daycare settings

Objective:

Noroviruses are the leading cause of acute gastroenteritis in the United States and outbreaks frequently occur in daycare settings. Results of norovirus vaccine trials have been promising, however there are open questions as to whether vaccination of daycare children would be cost-effective. We investigated the incremental cost-effectiveness of a hypothetical norovirus vaccination for children in daycare settings compared to no vaccination.

Methods:

We conducted a model-based cost-effectiveness analysis using a disease transmission model of children attending daycare. Vaccination with a 90% coverage rate in addition to the observed standard of care (exclusion of symptomatic children from daycare) was compared to the observed standard of care. The main outcomes measures were infections and deaths averted, quality-adjusted life years (QALYs), costs, and incremental cost-effectiveness ratio (ICER). Cost-effectiveness was analyzed from a societal perspective, including medical costs to children as well as productivity losses of parents, over a two-year time horizon. Data sources included outbreak surveillance data and published literature.

Results:

A 50% efficacious norovirus vaccine averts 571.83 norovirus cases and 0.003 norovirus-related deaths per 10,000 children compared to the observed standard of care. A $200 norovirus vaccine that is 50% efficacious has a net cost increase of $178.10 per child and 0.025 more QALYs, resulting in an ICER of $7,028/QALY. Based on the probabilistic sensitivity analysis, we estimated that a $200 vaccination with 50% efficacy was 94.0% likely to be cost-effective at a willingness-to-pay of $100,000/QALY threshold and 95.3% likely at a $150,000/QALY threshold.

Conclusion:

Due to the large disease burden associated with norovirus, it is likely that vaccinating children in daycares could be cost-effective, even with modest vaccine efficacy and a high per-child cost of vaccination. Norovirus vaccination of children in daycare has a cost-effectiveness ratio similar to other commonly recommended childhood vaccines.

Potential Clinical and Economic Value of Norovirus Vaccination in the Community Setting

INTRODUCTION

With norovirus vaccine candidates currently under development, now is the time to identify the vaccine characteristics and implementation thresholds at which vaccination becomes cost effective and cost saving in a community setting.

METHODS

In 2020, a norovirus transmission, clinical, and economics computational simulation model representing different U.S. population segments was developed to simulate the spread of norovirus and the potential impact of vaccinating children aged <5 years and older adults (aged ≥65 years).

RESULTS

Compared with no vaccination, vaccinating preschool-aged children averted 8%-72% of symptomatic norovirus cases in a community, whereas vaccinating older adults averted 2%-29% of symptomatic cases (varying with vaccine efficacy [25%-75%] and vaccination coverage [10%-80%]). Vaccination with a 25% vaccine efficacy was cost effective (incremental cost-effectiveness ratio ≤$50,000 per quality-adjusted life year) when vaccination cost ≤$445 and cost saving at ≤$370 when vaccinating preschool-aged children and ≤$42 and ≤$30, respectively, when vaccinating older adults. With a 50% vaccine efficacy, vaccination was cost effective when it cost ≤$1,190 and cost saving at ≤$930 when vaccinating preschool-aged children and ≤$110 and ≤$64, respectively, when vaccinating older adults. These cost thresholds (cost effective and cost saving, respectively) further increased with a 75% vaccine efficacy to ≤$1,600 and ≤$1,300 for preschool-aged children and ≤$165 and ≤$100 for older adults.

CONCLUSIONS

This study outlines thresholds at which a norovirus vaccine would be cost effective and cost saving in the community when vaccinating children aged <5 years and older adults. Establishing these thresholds can help provide decision makers with targets to consider when developing and implementing a norovirus vaccine.

Norovirus and Other Viral Causes of Medically Attended Acute Gastroenteritis Across the Age Spectrum: Results from the Medically Attended Acute Gastroenteritis Study in the United States

BACKGROUND

Acute gastroenteritis (AGE) causes a substantial burden in the United States, but its etiology frequently remains undetermined. Active surveillance within an integrated healthcare delivery system was used to estimate the prevalence and incidence of medically attended norovirus, rotavirus, sapovirus, and astrovirus.

METHODS

Active surveillance was conducted among all enrolled members of Kaiser Permanente Northwest during July 2014-June 2016. An age-stratified, representative sample of AGE-associated medical encounters were recruited to provide a stool specimen to be tested for norovirus, rotavirus, sapovirus, and astrovirus. Medically attended AGE (MAAGE) encounters for a patient occurring within 30 days were grouped into 1 episode, and all-cause MAAGE incidence was calculated. Pathogen- and healthcare setting-specific incidence estimates were calculated using age-stratified bootstrapping.

RESULTS

The overall incidence of MAAGE was 40.6 episodes per 1000 person-years (PY), with most episodes requiring no more than outpatient care. Norovirus was the most frequently detected pathogen, with an incidence of 5.5 medically attended episodes per 1000 PY. Incidence of norovirus MAAGE was highest among children aged < 5 years (20.4 episodes per 1000 PY), followed by adults aged ≥ 65 years (4.5 episodes per 1000 PY). Other study pathogens showed similar patterns by age, but lower overall incidence (sapovirus: 2.4 per 1000 PY; astrovirus: 1.3 per 1000 PY; rotavirus: 0.5 per 1000 PY).

CONCLUSIONS

Viral enteropathogens, particularly norovirus, are important contributors to MAAGE, especially among children < 5 years of age. The present findings underline the importance of judicious antibiotics use for pediatric AGE and suggest that an effective norovirus vaccine could substantially reduce MAAGE.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

Molecular epidemiology of astrovirus in children with gastroenteritis in southwestern Nigeria

Human astrovirus (HAstV) is recognized as one of the major causative agents of acute gastroenteritis in children worldwide. Data on the genetic diversity of HAstV in Nigeria are limited. The aim of this study was to determine the prevalence and molecular epidemiology of classical HAstV in children under 5 years of age with acute gastroenteritis in Ogun State, Nigeria. Fecal samples (331) as well as socio-demographic and clinical data were collected across the three senatorial districts of the state from February 2015 to April 2017. One hundred seventy-five samples were randomly selected and analyzed for the presence of HAstV using RT-PCR. PCR amplicons from positive samples were sequenced, and phylogenetic analysis was done to determine genotypes and lineages. The overall prevalence rate was 19.4% (34), with the highest occurrence observed in 2015 (41.4%). Viral coinfections were detected in 13 cases (38.2%). HAstV infection occurred throughout the year and in all age groups, mainly in the age group of 0-12 months. There was significant association between prevalence rate and collection year; however, no association was observed with gender, age, symptoms or risk factors. HAstV-5 was the predominant genotype (76.5%) circulating throughout the study period, followed by HAstV-1 (23.5%), which circulated only in the first 2 years of the study. Phylogenetic analysis showed that all HAstV-5 strains detected belonged to the 5a lineage, while HAstV-1 strains were grouped into lineage 1b. This study, to the best of our knowledge, is the first comprehensive report on molecular characterization of classical HAstV among children with gastroenteritis in the country, and this will serve as baseline information for implementing appropriate infection control practices.

Attribution of Pediatric Acute Gastroenteritis Episodes and Emergency Department Visits to Norovirus Genogroups I and II

BACKGROUND

Norovirus is a leading cause of acute gastroenteritis. With vaccines in development, population-based estimates of norovirus burden are needed to identify target populations, quantify potential benefits, and understand disease dynamics.

METHODS

We estimated the attributable fraction (AF) for norovirus infections in children, defined as the proportion of children testing positive for norovirus whose gastroenteritis was attributable to norovirus. We calculated the standardized incidence and emergency department (ED) visit rates attributable to norovirus using provincial gastroenteritis visit administrative data.

RESULTS

From 3731 gastroenteritis case patients and 2135 controls we determined that the AFs were 67.0% (95% confidence interval [CI], 31.5%-100%) and 91.6% (88.8%-94.4%) for norovirus genogroups I (GI) and II (GII), respectively. Norovirus GII AF varied by season but not age. We attributed 116 episodes (95% CI, 103-129) and 59 (51-67) ED visits per 10 000 child-years to norovirus GII across all ages, accounting for 20% and 18% of all medically attended gastroenteritis episodes and ED visits, respectively.

CONCLUSIONS

In children, a large proportion of norovirus GII detections reflect causation, demonstrating significant potential for norovirus GII vaccines. Seasonal variation in the norovirus GII AF may have implications for understanding the role asymptomatic carriage plays in disease dynamics.

Incidence, etiology, and severity of acute gastroenteritis among prospectively enrolled patients in 4 Veterans Affairs hospitals and outpatient centers, 2016-18

BACKGROUND

Acute gastroenteritis (AGE) burden, etiology, and severity in adults is not well-characterized. We implemented a multisite AGE surveillance platform in 4 Veterans Affairs Medical Centers (Atlanta, Bronx, Houston and Los Angeles), collectively serving >320,000 patients annually.

METHODS

From July 1, 2016-June 30, 2018, we actively identified AGE inpatient cases and non-AGE inpatient controls through prospective screening of admitted patients and passively identified outpatient cases through stool samples submitted for clinical diagnostics. We abstracted medical charts and tested stool samples for 22 pathogens via multiplex gastrointestinal PCR panel followed by genotyping of norovirus- and rotavirus-positive samples. We determined pathogen-specific prevalence, incidence, and modified Vesikari severity scores.

RESULTS

We enrolled 724 inpatient cases, 394 controls, and 506 outpatient cases. Clostridioides difficile and norovirus were most frequently detected among inpatients (cases vs controls: C. difficile, 18.8% vs 8.4%; norovirus, 5.1% vs 1.5%; p<0.01 for both) and outpatients (norovirus: 10.7%; C. difficile: 10.5%). Incidence per 100,000 population was highest among outpatients (AGE: 2715; C. difficile: 285; norovirus: 291) and inpatients ≥65 years old (AGE: 459; C. difficile: 91; norovirus: 26). Clinical severity scores were highest for inpatient norovirus, rotavirus, and Shigella/EIEC cases. Overall, 12% of AGE inpatient cases had ICU stays and 2% died; 3 deaths were associated with C. difficile and 1 with norovirus. C. difficile and norovirus were detected year-round with a fall/winter predominance.

CONCLUSIONS

C. difficile and norovirus were leading AGE pathogens in outpatient and hospitalized US Veterans, resulting in severe disease. Clinicians should remain vigilant for bacterial and viral causes of AGE year-round.

A phase 2 study of the bivalent VLP norovirus vaccine candidate in older adults; impact of MPL adjuvant or a second dose

INTRODUCTION

Acute norovirus gastroenteritis causes significant morbidity and in uncommon cases fatality in older adults. We investigated the safety and immunogenicity of bivalent virus-like particle (VLP) vaccine candidate formulations with and without monophosphoryl lipid A (adjuvant MPL) in this population.

METHODS

In this phase II, double-blind, controlled trial 294 healthy adults, ≥ 60 years of age, were randomized (1:1:1:1) to four groups to receive one or two intramuscular immunizations 28 days apart, with 26 18-49 year-old controls who received one MPL-free dose. One-dose groups received placebo on Day 1. Vaccine formulations contained 15 μg GI.1 and 50 μg GII.4c VLP antigens and 500 μg Al(OH)₃, with or without 15 μg MPL. We measured histo-blood group antigen blocking (HBGA) antibodies and ELISA Ig at Days 1, 8, 29, 57, 211 and 393, and avidity indices and cell-mediated immunity (CMI). Solicited local and systemic adverse events (AE) were assessed for 7 days and unsolicited AEs for 28 days after each injection.

RESULTS

After one dose HBGA antibodies to both VLP antigens increased with similar kinetics and magnitude in all groups; geometric mean titres (GMTs) persisted above baseline through Day 393. GMTs were similar across age strata (18-49, 60-74, 75-84 and ≥ 85 years of age) and unaffected by a second vaccination or MPL. Total Ig showed similar responses. No clinically relevant differences or changes in avidity or CMI were observed between formulations. Both formulations were well tolerated with no vaccine-related SAEs, the most frequent AEs being mild injection site pain and fatigue.

CONCLUSIONS

Adults over 60 years of age displayed no safety concerns and had similar immune responses to the norovirus VLP vaccine candidate as younger adults, unaffected by increasing age, a second dose or inclusion of MPL. This data supports the further development of the MPL-free vaccine candidate for older adults.

Development and evaluation of a multiplex conventional reverse-transcription polymerase chain reaction assay for detection of common viral pathogens causing acute gastroenteritis

Timely identification of etiological agents of enteric infections is necessary to reduce the burden of infantile diarrheal mortality. Nucleic acid amplification-based detection methods offer a quick, reliable way for diagnosis of microbes in clinical specimens. This study was undertaken to evaluate an easy-to-use, cost-effective multiplex conventional reverse-transcription polymerase chain reaction (RT-PCR) assay developed at the Indian Council of Medical Research-National Institute of Cholera and Enteric Diseases virology laboratory to identify 4 common enteric viruses (rotavirus, norovirus, adenovirus, astrovirus) in stool samples from patients who were being evaluated for acute diarrhea. On comparison with a commercially available real-time PCR method, significant agreement in sensitivity and specificity was observed. Though the turnaround time for RT-PCR was 6-8 h compared to 5-6 h for real-time PCR, the real-time PCR has high test cost (approximately 28 USD/2000 INR) for Fast-Track Diagnostics kit-based quantitative RT-PCR versus 6 USD or 400 INR for conventional multiplex RT-PCR/sample. Thus, the conventional RT-PCR method is expected to be adaptable at local hospitals and health cares in resource-poor settings.

UV Inactivation of Rotavirus and Tulane Virus Targets Different Components of the Virions

Enteric viruses are shed in fecal material by humans and other animals and are common contaminants in wastewater and surface water. Wastewater treatment plants often disinfect this effluent with low-pressure and medium-pressure UV lamps, which emit 254-nm and 220- to 280-nm irradiation, respectively. It is not known whether this treatment is efficacious against enteric viruses or how such treatments may inactivate these enteric viruses. This study examined UV disinfection for two enteric viruses: rotavirus (RV) (strain OSU with double-stranded RNA and a three-layer capsid) and Tulane virus (TV) (a cultivable surrogate for human norovirus with single-stranded RNA and a single-layer capsid). Viruses were treated with UV irradiation at 220 or 254 nm under conditions relevant to wastewater stabilization ponds, whose water is often used for irrigation. TV was susceptible to 220- or 254-nm UV at similar levels. It appears that UV irradiation inactivated TV by mutagenizing both its genome and capsid binding proteins. RV was more susceptible to UV at 220 nm than to UV at 254 nm. UV irradiation of RV at either 220 or 254 nm resulted in a virus that retained its ability to bind to its host cell receptor. After 220-nm treatment, the VP7 segment of the RV genome could not be amplified by PCR, suggesting that this treatment mutagenized the viral genome. However, this correlation was not observed when UV at 254 nm was used. Thus, RV and TV, with different genome and capsid contents, are targeted by UV irradiation in different ways.IMPORTANCE UV irradiation is becoming common for disinfection in water treatment plants, but little is known about the effectiveness of this treatment for enteric RNA viruses. Here, we observed that 220-nm UV irradiation was efficacious against rotavirus (RV) and Tulane virus (TV). UV irradiation at 254 nm inactivated TV to a greater extent than RV. Additional assays showed that UV irradiation compromised different portions of the RV and TV life cycles. UV irradiation decreased the binding of TV to its host receptor and mutagenized the TV genome. UV irradiation at 220 nm appeared to allow RV-host receptor interaction but halted RV genome replication. These findings provide knowledge about the disinfection of waterborne viruses, information that is important for the safe reuse or release of treated wastewater.

Gastroenteritis, Viral

Viral gastroenteritis (VGE) is an acute, self-limiting gastrointestinal infection caused by several viruses which most often trigger nausea, vomiting, abdominal pain and diarrhea. It is one of the most common human illnesses with its greatest impact on the very young and elderly. In the developing world, VGE can be life threatening whereas in most developed countries, it is self-limited and managed with hydration. Most agents of VGE are spread by the fecal oral route or may occur in explosive outbreaks due to food or water contamination. Control of these infections depends upon proper food handling, hand hygiene, clean water and the rotavirus vaccination of infants. This chapter will discuss the common viruses which cause this syndrome.

Evaluation of the RIDA®GENE RT-PCR assays for detection of sapovirus, astrovirus, adenovirus, and rotavirus in stool samples of adults in Switzerland

Sapovirus (SaV) and astrovirus (AstV) increasingly are recognized as cause of acute viral gastroenteritis (AGE). We evaluated the real-time RT-PCR assays RIDA®GENE SaV and viral stool panel II (RGN RT-PCR) for detection of SaV, AstV, adenovirus (AdV) F40/41 and rotavirus (RoV) in clinical stool samples (n = 69). Results were compared with reference singleplex RT-PCRs. The sensitivity for SaV, AstV and RoV are 100%, the specificity ranges from 98.1% to 100%. In 10 out of 11 AdV (all types) samples, the RGN RT-PCR for AdV F40/41 displayed negative results. Retrospectively, 196 stool specimens from adult patients previously tested negative for norovirus (NoV) were analyzed. In about 10% of NoV-negative stool samples, AdV (n = 9), RoV (n = 6), AstV (n = 3) or SaV (n = 3) were found. The RGN RT-PCR assays are useful for detection of enteric viruses other than NoV. This study emphasizes the need for further testing of NoV-negative stool samples in patients with AGE.

A prospective comparative study of children with gastroenteritis: emergency department compared with symptomatic care at home

Little is known about the epidemiology and severity of gastroenteritis among children treated at home. We sought to compare illness severity and etiology between children brought for emergency department (ED) care to those managed at home (i.e., community). Prospective cohort study of children enrolled between December 2014 and December 2016 in two pediatric EDs in Alberta, Canada along with children treated at home after telephone triage (i.e., community). Primary outcomes were maximal frequency of vomiting and diarrhea in the 24-h pre-enrollment period; secondary outcomes included etiologic pathogens, dehydration severity, future healthcare visits, and treatments provided. A total of 1613 patients (1317 ED, 296 community) were enrolled. Median maximal frequency of vomiting was higher in the ED cohort (5 (3, 10) vs. 5 (2, 8); P < 0.001). Proportion of children with diarrhea and its 24-h median frequency were lower in the ED cohort (61.3 vs. 82.8% and 2 (0, 6) vs. 4 (1, 7); P < 0.001, respectively). In regression analysis, the ED cohort had a higher maximum number of vomiting episodes pre-enrollment (incident rate ratio (IRR) 1.25; 95% CI 1.12, 1.40) while the community cohort had higher maximal 24-h period diarrheal episodes (IRR 1.20; 95% CI 1.01, 1.43). Norovirus was identified more frequently in the community cohort (36.8% vs. 23.6%; P < 0.001). Children treated in the ED have a greater number of vomiting episodes; those treated at home have more diarrheal episodes. Norovirus is more common among children treated symptomatically at home and thus may represent a greater burden of disease than previously thought.

Family income and exposure to norovirus in childhood: Findings from the UK Millennium Cohort Study

Children from low income families are at greater risk of poorer health outcomes than their wealthier peers. Hospital admissions for children with gastroenteritis increase as deprivation increases. Noroviruses are responsible for 47-96% of outbreaks of acute paediatric gastroenteritis, and 5-36% of sporadic cases worldwide. However, evidence on the relationship between family income and childhood exposure to norovirus is still limited, with published studies pointing to conflicting results. This study explored the relationship between family income and early childhood exposure to norovirus in the United Kingdom using data from the Millennium Cohort Study linked to serological data. Exposure to norovirus was measured by the level of human norovirus-specific antibodies (titres) obtained from oral fluid samples collected from 5962 pre-school age UK children and tested for Norovirus-specific Immunoglobulin G (IgG). Multivariable linear and quantile regression analyses were conducted to investigate the extent to which family income was associated with child norovirus exposure, and to explore the potential mechanisms through which income might translate into norovirus exposure. Higher norovirus-specific IgG titres were associated with higher family income, but the relationship weakened after controlling for potential mediating factors, mainly increased opportunities for person-to-person contacts, such as formal childcare arrangements. This study provides novel evidence that can help inform and prioritise policy interventions (e.g. vaccination) and health promotion programmes to reduce child health inequalities in the area of gastrointestinal infections.

Active Surveillance for Norovirus in a US Veterans Affairs Patient Population, Houston, Texas, 2015-2016

Background

Norovirus is a leading cause of acute gastroenteritis (AGE); however, few data exist on endemic norovirus disease burden among adults. Candidate norovirus vaccines are currently in development for all ages, and robust estimates of norovirus incidence among adults are needed to provide baseline data.

Methods

We conducted active surveillance for AGE among inpatients at a Veterans Affairs (VA) hospital in Houston, Texas. Patients with AGE (≥3 loose stools, ≥2 vomiting episodes, or ≥1 episode of both loose stool and vomiting, within 24 hours) within 10 days of enrollment and non-AGE control patients were enrolled. Demographic data and clinical characteristics were collected. Stool samples were tested using the FilmArray gastrointestinal panel; virus-positives were confirmed by real-time reverse transcription polymerase chain reaction and genotyped by sequencing.

Results

From November 2, 2015 through November 30, 2016, 147 case patients and 19 control patients were enrolled and provided a stool specimen. Among case patients, 139 (95%) were male and 70 (48%) were aged ≥65 years. Norovirus was the leading viral pathogen detected (in 16 of 20 virus-positive case patients) and accounted for 11% of all AGE cases. No viral pathogens were detected among control patients. Incidence of norovirus-associated hospitalization was 20.3 cases/100 000 person-years and was similar among those aged <65 and ≥65 years.

Conclusions

This active surveillance platform employed screening and enrollment of hospitalized VA patients meeting a standardized AGE case definition, as well as non-AGE control patients. Data from this study highlight the burden of norovirus in a VA inpatient population and will be useful in policy considerations of a norovirus vaccine.

[Acute Viral Gastroenteritis: Viruses Other Than Norovirus]

Acute Viral Gastroenteritis: Viruses Other Than Norovirus Abstract. Norovirus is the leading cause of acute viral gastroenteritis. Norovirus is highly contagious, thus outbreaks of norovirus in hospitals and long-term care facilities are feared. Usually, stool samples of patients with a potentially viral gastroenteritis are first checked for the presence of norovirus. In recent years, sapovirus and astrovirus were increasingly reported as cause of acute gastroenteritis. Outbreaks of acute viral gastroenteritis caused by sapovirus or astrovirus are hardly distinguishable from those caused by norovirus because of a similar clinical presentation. Molecular analyses of stool specimen are needed for accurate diagnosis of the viral cause of acute gastroenteritis. It is worth to further investigate stool samples of patients suspected of acute viral gastroenteritis not only for norovirus, but also for sapovirus and astrovirus.

The Population-Level Impacts of Excluding Norovirus-Infected Food Workers From the Workplace: A Mathematical Modeling Study

Norovirus is the leading cause of acute gastroenteritis and foodborne disease in the United States. The Food and Drug Administration recommends that food workers infected with norovirus be excluded from the workplace while symptomatic and for 48 hours after their symptoms subside. Compliance with this recommendation is not ideal, and the population-level impacts of changes in food-worker compliance have yet to be quantified. We aimed to assess the population impacts of varying degrees of compliance with the current recommendation through the use of a compartmental model. We modeled the number and proportion of symptomatic norovirus cases averted annually in the US population (using data from 1983-2014) in specific age groups (children aged <5 years, children aged 5-17 years, adults aged 18-64 years, and adults aged ≥65 years) under various scenarios of food-worker exclusion (i.e., proportion compliant and days of postsymptomatic exclusion) in comparison with a referent scenario which assumed that 66.6¯% of norovirus-symptomatic food workers and 0% of postsymptomatic food workers were excluded from work. Overall, we estimated that 6.0 million cases of norovirus have already been avoided annually under the referent scenario and that 6.7 million (28%) more cases might be avoided through 100% compliance with the current recommendations. Substantial population-level benefits were predicted from improved compliance in exclusion of norovirus-infected food workers from the workplace-benefits that may be realized through policies or programs incentivizing self-exclusion.

Norovirus, astrovirus, and sapovirus among immunocompromised patients at a tertiary care research hospital

We estimated the prevalence of astrovirus, sapovirus, and norovirus among patients enrolled in research protocols and receiving medical care at the Clinical Center of the National Institutes of Health, Bethesda, MD, a clinical research hospital with a large immunocompromised patient population. We identified patients whose fecal specimens were submitted to the Clinical Center for testing on the Biofire FilmArray Gastrointestinal Panel from September 15, 2015 through November 30, 2016. Among 442 patients with fecal specimens submitted for multiplex testing, 11% had norovirus identified, 2% had astrovirus, and 2% had sapovirus. Like norovirus, astrovirus was detected in multiple sequential samples from a single patient, consistent with chronic infection or the occurrence of multiple reinfections. Coinfection with non-viral gastrointestinal pathogens was detected in 31% of patients with positive results for norovirus, astrovirus, or sapovirus. Norovirus remains common in this immunocompromised patient population, and both sapovirus and astrovirus are present.

Application of a salivary immunoassay in a prospective community study of waterborne infections

Quantifying sporadic waterborne infections in community settings can be challenging. Salivary antibody immunoassays are a promising non-invasive tool that can be used in prospective studies of common infections, especially those involving children. This study was conducted in a Massachusetts city, which uses a microbiologically contaminated river as its water source, during summer-early winter periods before and after construction of a new drinking water treatment plant. Monthly saliva samples (7480 samples from 1170 children and 816 adults) were analyzed for immunoglobulin G (IgG) responses to recombinant proteins of Cryptosporidium, one genogroup I (GI) and two GII noroviruses. Immunoconversion was defined as at least four-fold increase in specific antibody responses between two monthly samples with a post-conversion response above a flexible age-dependent cut-off. Episodes of gastroenteritis (diarrhea or vomiting or cramps) were associated with 3.2 (95% confidence limits 1.1; 9.5) adjusted odds ratio (aOR) of immunoconversion to Cryptosporidium; episodes of combined diarrhea and vomiting symptoms were associated with 3.5 (0.8; 15.0) and 4.6 (1.7; 12.6) aORs of an immunoconversion to GI and GII noroviruses, respectively. Swimming in natural water bodies or chlorinated pools was associated with 2.3 (0.4; 15.4) and 4.9 (1.6; 15.5) aORs of immunoconversion to Cryptosporidium, respectively. In a subset of study participants who did not use home water filters, consumption of at least some amount of non-boiled tap water reported in a monthly recall survey was associated with 11.1 (1.2; 100.0) and 0.6 (0.1; 2.5) aORs of immunoconversion to Cryptosporidium before and after the new water treatment plant construction, respectively. Among individuals who used home water filters, associations between non-boiled tap water consumption and Cryptosporidium immunoconversion were not significant before and after new plant construction with aORs of 0.8 (0.2; 3.3) and 0.3 (0.1; 1.6), respectively. The interaction effect of study phase and non-boiled tap water consumption on Cryptosporidium immunoconversions was statistically significant in the entire study population with aOR of 5.4 (1.1; 25.6). This was the first study that has used a salivary antibody immunoassay to demonstrate significant associations between gastrointestinal symptoms and Cryptosporidium and norovirus infections, and between water-related exposures and Cryptosporidium infections.

A model for rapid, active surveillance for medically-attended acute gastroenteritis within an integrated health care delivery system

Background

This study presents a novel methodology for estimating all-age, population-based incidence rates of norovirus and other pathogens that contribute to acute gastroenteritis in the United States using an integrated healthcare delivery system as a surveillance platform.

Methods

All cases of medically attended acute gastroenteritis within the delivery system were identified from April 1, 2014 through September 30, 2016. A sample of these eligible patients were selected to participate in two phone-based surveys and to self-collect a stool sample for laboratory testing. To ascertain household transmission patterns, information on household members with acute gastroenteritis was gathered from participants, and symptomatic household members were contacted to participate in a survey and provide stool sample as well.

Results

54% of individuals who met enrollment criteria agreed to participate, and 76% of those individuals returned a stool sample. Among household members, 85% of eligible individuals agreed to participate, and 68% of those returned a stool sample. Participant demographics were similar to those of the eligible population, although minority racial/ethnic groups were somewhat underrepresented in the final sample.

Conclusions

This study demonstrates the feasibility of conducting acute infectious disease research within an integrated health care delivery system. The surveillance, sampling, recruitment, and data collection methods described here are broadly applicable to conduct baseline and epidemiological assessments, as well as for other research requiring representative samples of stool specimens.

Incidence of Norovirus-Associated Diarrhea and Vomiting Disease Among Children and Adults in a Community Cohort in the Peruvian Amazon Basin

Background

Data on norovirus epidemiology among all ages in community settings are scarce, especially from tropical settings.

Methods

We implemented active surveillance in 297 households in Peru from October 2012 to August 2015 to assess the burden of diarrhea and acute gastroenteritis (AGE) due to norovirus in a lower-middle-income community. During period 1 (October 2012-May 2013), we used a "traditional" diarrhea case definition (≥3 loose/liquid stools within 24 hours). During period 2 (June 2013-August 2015), we used an expanded case definition of AGE (by adding ≥2 vomiting episodes without diarrhea or 1-2 vomiting episodes plus 1-2 loose/liquid stools within 24 hours). Stool samples were tested for norovirus by reverse-transcription polymerase chain reaction.

Results

During period 1, overall diarrhea and norovirus-associated diarrhea incidence was 37.2/100 person-years (PY) (95% confidence interval [CI], 33.2-41.7) and 5.7/100 PY (95% CI, 3.9-8.1), respectively. During period 2, overall AGE and norovirus-associated AGE incidence was 51.8/100 PY (95% CI, 48.8-54.9) and 6.5/100 PY (95% CI, 5.4-7.8), respectively. In both periods, children aged <2 years had the highest incidence of norovirus. Vomiting without diarrhea occurred among norovirus cases in participants <15 years old, but with a higher proportion among children <2 years, accounting for 35% (7/20) of all cases in this age group. Noroviruses were identified in 7% (23/335) of controls free of gastroenteric symptoms.

Conclusions

Norovirus was a significant cause of AGE in this community, especially among children <2 years of age. Inclusion of vomiting in the case definition resulted in a 20% improvement for detection of norovirus cases.