Norovirus Outbreaks Research Articles

Simultaneous norovirus outbreak in three Portuguese army bases in the Lisbon region, December 2017

IntroductionNorovirus outbreaks frequently occur in communities and institutional settings acquiring a particular significance in armed forces where prompt reporting is critical. Here we describe the epidemiological, clinical and laboratorial investigation...

Norovirus Detection in Environmental Samples from Norovirus Outbreaks in Schools and Kindergartens - Beijing Municipality, China, October-December 2020.

What is already known on this topic?The norovirus has often caused outbreaks in schools and kindergartens, but minimal research has been performed on environmental contamination during norovirus outbreaks in schools and kindergartens.What is added by this report?This report conveys the norovirus detection rates and viral loads in different environmental sites in 45 norovirus outbreaks in Beijing Municipality from October to December 2020.What are the implications for public health practice?The evidence presented here can instruct professionals and the public to sample and disinfect key locations of the environment purposefully when responding to norovirus outbreaks.

Molecular Epidemiological Characteristics of Gastroenteritis Outbreaks Caused by Norovirus GII.4 Sydney [P31] Strains - China, October 2016-December 2020.

IntroductionHuman noroviruses are the leading cause of acute viral gastroenteritis (AGE) worldwide in all age groups. GII.4 strains have been the predominant genotype circulating globally over the last 2 decades and since 2012. GII.4 Sydney viruses have emerged and caused the majority of AGE outbreaks worldwide.MethodsData from norovirus outbreaks from the laboratory-based surveillance of norovirus outbreaks in China (CaliciNet China) between October 2016–December 2020 were analyzed.ResultsDuring October 2016–December 2020, 1,954 norovirus outbreaks were reported, and positive fecal samples from 1,352 (69.19%) outbreaks were genotyped. GII.4 Sydney [P31] viruses accounted for 2.1% (October 2016–August 2017), 5.5% (September 2017–August 2018), 3.3% (September 2018–August 2018), 26.6% (September 2019–August 2020), and and 1.1% (September 2020–December 2020) of GII outbreaks, respectively. Compared to reference strains of GII.4 Sydney [P31] from 2012 to 2013, 7 amino acid mutations in epitopes[A (297, 372 and 373), B (333), E (414), and H (309 and 310)] and 1 in human histo-blood group antigens binding site at site II 372 were found by analyzing 9 GII.4 Sydney [P31] complete genomic sequences.ConclusionsThis report identified the genomic variation of GII.4 Sydney [P31] from CaliciNet China. Continued surveillance with prompt genotyping and genetic analysis is necessary to monitor the emergence of novel GII.4 variants.

Factors Influencing the Health Behavior During Public Health Emergency: A Case Study on Norovirus Outbreak in a University

It is known that health belief and health literacy are closely related to health behavior. But, we do not know explicitly how health belief and health literacy interact with each other and determine health behavior change under public health emergencies (PHE). Through the integration of constructs from health belief model (perceived susceptibility, severity, benefits, barriers, and self-efficacy) and diverse dimensions of health literacy (functional, interactive and critical), a research framework is proposed to examine the underlying mechanism of health behavior change during PHE. Structural equation modeling (SEM) was used to analyze 386 questionnaire data collected from Chinese university students for the research framework. The analysis results show that (1) both health belief and health literacy have significant impacts on health behavior change during PHE. However, health belief plays a mediating role which affects the health literacy's impact on health behavior; (2) while the increase of perceived severity of disease and self-efficacy promote the health behavior change, the effectiveness of perceived susceptibility on health behavior depends on the increase of perceived severity; and (3) the enhancement of interactive health literacy effectively promotes health behavior change, while functional and critical health literacy reduces the blind change. The results throw lights on health education services and provide references and factors in understanding and encouraging health behavior changes to relevant stakeholders including social media operators, practitioners, social service providers, and policy makers.

Viral intra-host evolution in immunocompetent children contributes to human norovirus diversification at the global scale

ABSTRACT Norovirus is a major cause of acute gastroenteritis. Human noroviruses present >30 different genotypes, with a single genotype (GII.4) predominating worldwide. Concurrent outbreaks of norovirus are often associated with the emergence of new viruses. While different hypotheses have been presented, the source of new mutations in noroviruses is still unknown. In this study, we applied high-resolution sequencing to determine the intra-host viral diversity presented by noroviruses during the acute and shedding phase of infection in children. Profiling viral intra-host diversification at nearly full genome level indicated that GII.4 viruses presented dynamic intra-host variation, while non-GII.4 viruses presented minimal variation throughout the infection. Notably, the intra-host genetic variation during the shedding phase recapitulates the genetic diversity observed at the global level, particularly those mapping at the VP1 antigenic sites. Thus the intra-host evolution in healthy children explains the source of norovirus mutations that results in diversification at the global scale.

Discovery of Potential Inhibitors for RNA-Dependent RNA Polymerase of Norovirus: Virtual Screening, and Molecular Dynamics.

Noroviruses are non-enveloped viruses with a positive-sense single-stranded RNA (ssRNA) genome belonging to the genus Norovirus, from the family Caliciviridae, which are accountable for acute gastroenteritis in humans. The Norovirus genus is subdivided into seven genogroups, i.e., (GI-GVII); among these, the genogroup II and genotype 4 (GII.4) strains caused global outbreaks of human norovirus (HuNov) disease. The viral genome comprises three open reading frames (ORFs). ORF1 encodes the nonstructural polyprotein that is cleaved into six nonstructural proteins, which include 3C-like cysteine protease (3CLpro) and a viral RNA-dependent RNA polymerase. ORF2 and ORF3 encode the proteins VP1 and VP2. The RNA-dependent RNA polymerase (RdRp) from noroviruses is one of the multipurpose enzymes of RNA viruses vital for replicating and transcribing the viral genome, making the virally encoded enzyme one of the critical targets for the development of novel anti-norovirus agents. In the quest for a new antiviral agent that could combat HuNov, high throughput virtual screening (HTVS), combined with e-pharmacophore screening, was applied to screen compounds from the PubChem database. CMX521 molecule was selected as a prototype for a similarity search in the PubChem online database. Molecular dynamics simulations were employed to identify different compounds that may inhibit HuNov. The results predicted that compound CID-57930781 and CID-44396095 formed stable complexes with MNV-RdRp within 50 ns; hence, they may signify as promising human norovirus inhibitors.

Involvement of Workers in Closed and Semiclosed Institutions in Outbreaks of Acute Gastroenteritis Due to Norovirus.

Norovirus outbreaks frequently occur in closed or semiclosed institutions. Recent studies in Catalonia and various countries indicate that, during outbreaks in these institutions, norovirus is detected in between 23% and 60% of workers, and the prevalence of infection in asymptomatic workers involved in outbreaks ranges from 17% to 40%. In this work, we carried out a prospective study to investigate the involvement of workers in closed and semiclosed institutions during outbreaks. The attack rates (ARs) and the rate ratios (RRs) were calculated according to the type of transmission and occupational category. The RRs and 95% confidence intervals (CIs) between workers and users were calculated. The mean cycle of quantification (Cq) values were compared according to the genogroup and the presence of symptoms. ARs were higher in person-to-person transmission than in common vehicle outbreaks, and 38.8% of workers were symptomatic. The RR between workers and users was 0.46 (95% CI 0.41–0.52). The ARs in workers were high, particularly in workers with closer contact with users. The mean Cq was lower in patients than in asymptomatic infected persons, although the difference was only significant for genogroup I (GI). The frequency of asymptomatic infected persons suggests that personal hygiene measures should be followed by all workers in the centers affected.

Circulation of GII.4 norovirus strains in children

Background: GII.4 norovirus strains have caused the majority of norovirus outbreaks and sporadic cases globally since the mid-1990s. New norovirus GII.4 strains emerge every 2–4 years, circulate widely, and replace older variants. Novel variants emerge through a combination of recombination, genetic drift, and selection possibly driven by population immunity. Variants of GII.4 viruses have caused all the 6 pandemics of acute gastroenteritis caused by noroviruses in the last 2 decades. Methods and materials: In order to study the diversity of circulating norovirus GII.4 strains in Vellore (south India) over a 13 years period, stool samples collected from children <5 years hospitalized for acute watery diarrhea at Christian Medical College, Vellore, from December 2005 to December 2018, were tested for norovirus GI and GII by multiplex one-step real-time PCR (qRT-PCR). Norovirus positive samples were genotyped by performing conventional PCR that amplified the ORF1-ORF2 junction region, followed by Sanger sequencing, and sequence data analysis of the ORF2 (major capsid protein VP gene). Results: A total of 3303 stool samples were tested, of which 13.7% (451/3303) were positive for norovirus. Of the 451 samples positive for norovirus by qRT-PCR, 69.8% (315/451) were genotyped (19 GI and 296 GII genotypes). 63.9% (189/296) of the GII positive samples were GII.4 genotype. During 2005–2006, GII.4 Yerseke (60%) was the most common GII.4 variant, followed by GII.4 Hunter (33.3%). During 2007, GII4 Den Haag (55%) emerged as the predominant strain, followed by GII.4 Osaka (35%). During 2008, GII.4 Osaka was the most common (81.8%), which was replaced by GII.4 New Orleans (50%) in 2009. GII.4 New Orleans continued to be the most common variant in 2011. In 2012, GII.4 Sydney (42.9%) emerged as the most common GII.4 variant, along with GII.4 New Orleans (42.9%). During the successive years from 2013 to 2018, GII.4 Sydney remained the predominant GII.4 variant in Vellore. Conclusion: The circulation of norovirus GII.4 variants in our setting is similar to that reported globally.

Detection of Norovirus in Saliva Samples from Acute Gastroenteritis Cases and Asymptomatic Subjects: Association with Age and Higher Shedding in Stool.

Norovirus infections are a leading cause of acute gastroenteritis outbreaks worldwide and across all age groups, with two main genogroups (GI and GII) infecting humans. The aim of our study was to investigate the occurrence of norovirus in saliva samples from individuals involved in outbreaks of acute gastroenteritis in closed and semiclosed institutions, and its relationship with the virus strain, virus shedding in stool, the occurrence of symptoms, age, and the secretor status of the individual. Epidemiological and clinical information was gathered from norovirus outbreaks occurring in Catalonia, Spain during 2017–2018, and stool and saliva samples were collected from affected and exposed resident individuals and workers. A total of 347 saliva specimens from 25 outbreaks were analyzed. Further, 84% of individuals also provided a paired stool sample. For GII infections, norovirus was detected in 17.9% of saliva samples from symptomatic cases and 5.2% of asymptomatic individuals. Positivity in saliva occurred in both secretors and nonsecretors. None of the individuals infected by norovirus GI was positive for the virus in saliva. Saliva positivity did not correlate with any of the studied symptoms but did correlate with age ≥ 65 years old. Individuals who were positive in saliva showed higher levels of virus shedding in stool. Mean viral load in positive saliva was 3.16 ± 1.08 log10 genome copies/mL, and the predominance of encapsidated genomes was confirmed by propidium monoazide (PMA)xx-viability RTqPCR assay. The detection of norovirus in saliva raises the possibility of oral-to-oral norovirus transmission during the symptomatic phase and, although to a lesser extent, even in cases of asymptomatic infections.

Norovirus outbreak causing gastroenteritis in a hotel in Menorca, Spain

ObjectivesTo establish the agent responsible for a gastroenteritis outbreak in a hotel in Menorca (Spain) in September 2016. MethodsThe study included epidemiological and laboratory analysis. Environmental and stool samples were examined for bacterial and viral pathogens. ResultsOne hundred and fifty-one cases were detected, 123 among the tourists staying in the hotel and 28 affecting the staff. The presence of genotype 2 norovirus was discovered in the microbiological studies of patient’s faeces, as well as in the surface samples of rooms and common areas. The control plan implemented allowed for control of the outbreak. ConclusionsThis study on a genotype 2 norovirus outbreak reveals the importance of a rapid response for controlling these types of outbreaks.

Acute gastroenteritis outbreaks in closed and semi-closed facilities during 2017 in Catalonia, Spain.

Acute gastroenteritis (AGE) is a leading cause of disease worldwide. The aim of this prospective observational study is to describe the epidemiology of AGE in closed and semi-closed institutions in Catalonia. In 2017, 151 outbreaks were reported; 30.5% occurred in closed and semi-closed institutions; 71.7% caused by norovirus (NoV) (1532) cases. Person-to-person transmission accounted for 75.8% of NoV outbreaks vs 46.1% in non-NoV outbreaks (p < 0.001). Attack rate for NoV outbreaks was 33.1% vs 14.3% for non-NoVoutbreaks (RR = 2.3; 95%CI: 2.0-2.7). The high number of affected underscores prompt and intense preventive measures to avoid the extension and perpetuation of outbreaks in these settings.

Molecular Monitoring of Enteropathogens in Sewage During NATO Exercise Trident Juncture 2018: Potential Tool in Early Outbreak Warning?

Outbreaks of gastrointestinal disease among military service personnel can have severe impact on operational effectivity and force readiness. Thus, early outbreak detection is critical to minimize spread. This pilot study aimed to explore field-based molecular screening of sewage as a supplemental tool in early outbreak warning before disease is diagnosed in personnel seeking medical care. Sewage from permanent (n = 3) and temporary (n = 3) military camps, hosting national and international military personnel, were sampled during the NATO Exercise TRJE18 taking place in southern Norway during fall 2018. Samples were screened for 22 gastrointestinal pathogens using multiplex PCR. Markers of multiple enteropathogens were detected in samples from all locations with some variations in diversity. Yersinia enterocolitica, pathogenic Escherichia coli, adenovirus, and Giardia were detected in sewage from all six camps during the exercise. Agent diversity seemed to increase with population size, regardless of nationality. Only a minor outbreak (n = 6) of norovirus was reported in one of the permanent camps. From the same camp, genetic markers of norovirus were detected in sewage 2 days before outbreak notification. No other outbreaks of gastrointestinal disease were reported during the exercise, indicating that markers of several enteropathogens can be normally found in sewage from healthy soldier populations. Thus, discriminating between true outbreaks and nonrelevant "background levels" would be of critical importance for correct decision-making in operational contexts. Molecular screening of sewage allows rapid detection of multiple gastrointestinal pathogens in biological waste from military camps. However, background levels of pathogens challenges interpretation of qualitative analyses in outbreak situations. As such, quantitative measures, as well as high-resolution sequence-based methods, which allows strain identification and broader target spectrum, should be further explored in future studies.

Detecting Foodborne Disease Outbreaks in Florida through Consumer Complaints

The Florida Complaint and Outbreak Reporting System (FL-CORS) database is used by the Florida Department of Health's Food and Waterborne Disease Program as one of the tools to detect foodborne disease outbreaks (FBOs). We present a descriptive and spatial network analysis of FL-CORS data collected during 2015 to 2018. We also quantified FBOs that were investigated and confirmed because of a filed complaint and the etiological agents involved in these outbreaks. An increasing number of unique complaints filed in FL-CORS was observed during 2015 to 2018, with a sharp increase during 2017 to 2018 and a different seasonal pattern in 2018. The preferred mechanism of reporting varied by age group, with younger people more frequently filing complaints online and older people preferring reporting in person or by phone. Spatial network analysis revealed that 87% of complaints had the same county of residence and county of presumed exposure. Frequency of complaints was negatively associated with linear distance between place of residence and place of exposure at the zip code level. Counties located in North and Central Florida, as well as some coastal areas in South Florida, had higher incidence rates of complaints. Those counties tend to have a large population density, and some are popular vacation destinations. On average, 96 FBOs were reported in Florida annually, of which 60% were confirmed with successful identification of the causative agent. The 56% of the confirmed FBOs were triggered by a complaint. Throughout the years, 2.4 to 2.8 FBOs and 1.4 confirmed FBOs were identified per 100 complaints. Ciguatera toxin was the cause of 40% of all FBOs in Florida, and only 28% of outbreaks were detected through complaints. In contrast, complaints were the main source of identifying outbreaks of norovirus, nontyphoidal Salmonella enterica, and scombroid food poisoning, as well as rare outbreaks of Clostridium perfringens, Cryptosporidium spp., Shigella spp., and Vibrio vulnificus.

Efficient management of a norovirus outbreak causing gastroenteritis in two hotels in Spain, 2014

ObjectivesTo determine the aetiological agent causing a gastroenteritis outbreak in two hotels in Majorca (Spain) on August and September 2014. MethodsAn epidemiological study was carried out. Environmental and stool samples were analyzed for different pathogens, including norovirus. ResultsEpidemiological analysis detected 79 cases among the tourists hosted in the affected hotels over the period 18th August to 3rd September. They included 52 (attack rate: 6.4%) and 27 (attack rate: 3.0%) cases in hotel A and B, respectively. Seven of the staff members were also affected. Microbiological analyses detected genotype 2 norovirus in patient's stool samples, in rooms and in common areas’ surfaces. The specific control plan rapidly implemented at the beginning of the outbreak, and further adapted for norovirus elimination, allowed to control the outbreak. ConclusionsOur study demonstrates that the outbreak was caused by genotype 2 norovirus, and reflects the importance of a rapid analysis and response for its control.

Identifying septic pollution exposure routes during a waterborne norovirus outbreak - A new application for human-associated microbial source tracking qPCR

In June 2017, the Pennsylvania Department of Health (PADOH) was notified of multiple norovirus outbreaks associated with 179 ill individuals who attended separate events held at an outdoor venue and campground over a month period. Epidemiologic investigations were unable to identify a single exposure route and therefore unable to determine whether there was a persistent contamination source to target for exposure mitigation. Norovirus was detected in a fresh recreational water designated swimming area and a drinking water well. A hydrogeological site evaluation suggested a nearby septic leach field as a potential contamination source via ground water infiltration. Geological characterization revealed a steep dip of the bedrock beneath the septic leach field toward the well, providing a viral transport pathway in a geologic medium not previously documented as high risk for viral ground water contamination. The human-associated microbial source tracking (MST) genetic marker, HF183, was used as a microbial tracer to demonstrate the hydrogeological connection between the malfunctioning septic system, drinking water well, and recreational water area. Based on environmental investigation findings, venue management and local public health officials implemented a series of outbreak prevention strategies including discontinuing the use of the contaminated well, issuing a permit for a new drinking water well, increasing portable toilet and handwashing station availability, and promoting proper hand hygiene. Despite the outbreaks at the venue and evidence of ground water contamination impacting nearby recreational water and the drinking water well, no new norovirus cases were reported during a large event one week after implementing prevention practices. This investigation highlights a new application for human-associated MST methods to trace hydrological connections between multiple fecal pollutant exposure routes in an outbreak scenario. In turn, pollutant source information can be used to develop effective intervention practices to mitigate exposure and prevent future outbreaks associated with human fecal contaminated waters.

FilmArray GI-panel performance for the rapid and multiple detection of gastrointestinal microorganisms in foodborne illness outbreaks in Shenzhen during 2018-2019.

Foodborne illness outbreaks can be caused by a great many of gastrointestinal microorganisms including bacteria, viruses and parasites. Acute gastroenteritis is most commonly found in such patients infected with at least one pathogen through food intake. The stool culture has been conventionally used to guide a single diagnosis and therapy. However, traditional methods for identification of a pathogen are time-consuming and have limited sensitivity, leading to false negatives and co-infection omission. The aim of this study was to characterize the multiple etiology of each foodborne illness outbreak in Shenzhen during 2018-2019 by the FilmArray GI panel, and to reveal the seasonality of each causative organism incurring outbreaks. All patients included had a FilmArray GI panel performance and the seasonal characteristics were recorded. A total of 173 patients suffered from foodborne illnesses in 32 outbreaks in Nanshan District of Shenzhen. In total, 365 microorganisms were detected of which 83.8% (306/365) corresponded to bacteria and 16.2% (59/365) to viruses. Co-infections with more than one microorganism were detected in 81.3% (26/32) of the outbreaks. In 153 (88.4%) of 173 patients at least two pathogens were identified. The most common diarrheal pathogen related to outbreaks was EPEC (56%), followed by ETEC (38%), Norovirus (34%), EAEC (28%), Vibrio (25%), Salmonella (22%), P. shigelloides (22%), C. difficile (16%), STEC (3%) and Sapovirus (3%). Bacterial outbreaks occurred with a seasonal distribution with the exception of C. difficile whereas Norovirus outbreaks predominated during the autumn-winter months. The use of the FilmArray GI panel has given us worthy information regarding the epidemiology of pathogens detected in patients with acute diarrhea. It also highlights the importance of multi-pathogen infections and the frequency of diarrheogenic E. coli in foodborne disease outbreaks. More significantly, the rapid and multiple findings may help quickly taking an appropriate precaution, control and treatment.

Diversity of Noroviruses throughout Outbreaks in Germany 2018.

Human norovirus accounts for the majority of viral gastroenteritis cases worldwide. It is a fast evolving virus generating diversity via mutation and recombination. Therefore, new variants and new recombinant strains emerge in the norovirus population. We characterized norovirus positive stool samples from one intensively studied district Märkisch-Oderland state Brandenburg with the samples from other states of Germany in order to understand the molecular epidemiological dynamics of norovirus outbreaks in Germany 2018. PCR systems, Sanger sequencing, and phylogenetic analyses were used for genotyping. Noroviruses of 250 outbreaks in Germany were genotyped, including 39 outbreaks for the district Märkisch-Oderland. Viral diversity in Märkisch-Oderland as compared to Germany was similar, but not identical. The predominant genogroup in Germany was GII with predominate genotype GII.P16-GII.4 Sydney, whereas GII.P31-GII.4 Sydney was the most frequent in Märkisch-Oderland. Genogroup I viruses were less frequently detected, regional and national. Within the sequences of GII.4 recombinants, two distinct clusters were identified with outbreaks from Märkisch-Oderland. Further analysis of sequence data and detailed epidemiological data are needed in order to understand the link between outbreaks in such clusters. Molecular surveillance should be based on samples collected nationally in order to trace comprehensive virus distribution and recombination events in virus population.

Developing a Clinically Informed Compartmental Mathematical Model of Pediatric Norovirus Transmission—A Feasibility Study

Background: Norovirus causes a significant disease burden of 20 million cases per year in the United States. Hospitals and long-term care facilities constitute the most commonly reported settings for noroviral outbreaks and clusters and thus represent a critically important site for prevention. Our institutional surveillance and response system identified 10–14 clusters or outbreaks of gastrointestinal viral disease per year, predominantly affecting staff. We sought to develop a compartmental mathematical model to examine the potential efficacy of various infection control practices in the management of noroviral clusters. Methods: We developed a set of parallel compartments representing both patient and staff categories (nursing, nurse assistants, etc) involved in a prototypical outbreak, using a 38-bed mixed medium- and high-acuity medical unit as the model basis. A susceptible–exposed–infected–recovered/immune (SEIR) model structure was used (Fig. 1). We conducted interviews with infection preventionists and nursing management to parameterize the model with data on (1) staff-to-patient ratios, (2) staff-patient contact time, (3) staff-staff contact time, (4) spatial distribution of patient assignments, and (5) baseline and intraoutbreak infection prevention practices. With these data, we proceeded to develop submodels, building on the primary model, that examined the effects of additional parallel compartmentalization of granular groups of staff, including resident physicians, environmental services, and clinical nursing assistants. Model parameters for these subanalyses were informed by interviews with clinical experts and review of internal data. Results and Conclusions: An SEIR model was developed that allowed for examination of a modeled outbreak of norovirus and comparison with a known prior outbreak on the same modeled unit for fidelity. Submodeling was performed with more staffing detail, allowing for the addition of further parallel SEIR tracks that delineated more granular staffing patterns. Staff interviews proved critical in the parameterization of these submodels, allowing for a more faithful representation of real-world dynamics. This work, through modification of model parameterization, can be used to assess the efficacy of hypothetical infection control interventions (eg, earlier unit closure, longer staff furlough) in altering transmission dynamics during an outbreak.Funding: NoneDisclosures: None

Successful Control of a Norovirus Outbreak in a Chilean Pediatric Intensive Care Unit

Background: Noroviruses are nonenveloped, single-stranded RNA viruses belonging to the Caliciviridae family; they cause high-profile outbreaks in healthcare settings, due to their contagiousness, prolonged viral shedding, and ability to survive in the environment. Methods: Description of a norovirus outbreak in a pediatric ICU with multibed rooms. We report the epidemiology, molecular diagnosis, and control. Results: In August and September 2019, an outbreak of acute gastroenteritis affected 13 patients and 26 healthcare workers at an intensive care unit of Roberto Del Río Children’s Hospital, which consists of 22 beds in a multibed-room format. Patients manifested self-limited nondysenteric diarrhea; other symptoms were vomiting (54%) and fever (23%). Healthcare workers reported diarrhea, nausea, vomiting, fever, malaise, and abdominal cramps. The mean age of the patients was 1 year old, all diaper users. The average days of diarrhea in patients was 4 days (2–6 days). There were 87 exposed patients, with an attack rate of 14.9% and 107 exposed staff, with an attack rate of 24.3%. Rotavirus and bacterial etiology were ruled out, and norovirus was subsequently diagnosed in 10 of 13 patients using qRT-PCR; 80% (8 of 10) corresponded with GII norovirus and 20% with a GI (2 of 10). Control measures included enforcement of standard precautions, strict adherence to contact precautions (use of gloves and gowns), hand hygiene before and after patients contact, and mask use if exposure to vomitus. Healthy staff were assigned for patients care. Environmental disinfection twice daily with 1.000 ppm sodium hypochlorite solution was encouraged and supervised with focus on cleaning high-touch surfaces, such as bathrooms, sinks, tables, floors and patient-care items. Active and prospective surveillance were conducted to search for new cases. Infection control practices were coupled with education to staff, patients, and visitors. The outbreak was controlled on September 18, 2019, after 23 days and several interventions, with complete recovery in all cases. Conclusions: We concluded that timely detection of a norovirus outbreak in a healthcare facility is imperative for effective infection control, especially in a multibed-room setting, because of the extended viral shedding in children and the transmission route that included aerosolized viral particles in vomitus. Molecular methods offer a rapid and definitive way to establish etiology, but these tests may not be accessible. Direct contact with infected children and contaminated surfaces and patient-care items were relevant risk factors in this outbreak (which involved both patients and healthcare workers) and contributed with its length.Funding: NoneDisclosures: None

Restaurant Policies and Practices Related to Norovirus Outbreak Size and Duration

Norovirus is the leading cause of foodborne illness outbreaks in the United States, and restaurants are the most common setting of foodborne norovirus outbreaks. Therefore, prevention and control of restaurant-related foodborne norovirus outbreaks is critical to lowering the burden of foodborne illness in the United States. Data for 124 norovirus outbreaks and outbreak restaurants were obtained from Centers for Disease Control and Prevention surveillance systems and analyzed to identify relationships between restaurant characteristics and outbreak size and duration. Findings showed that restaurant characteristics, policies, and practices were linked with both outbreak size and outbreak duration. Compared with their counterparts, restaurants that had smaller outbreaks had the following characteristics: managers received food safety certification, managers and workers received food safety training, food workers wore gloves, and restaurants had cleaning policies. In addition, restaurants that provided food safety training to managers, served food items requiring less complex food preparation, and had fewer managers had shorter outbreaks compared with their counterparts. These findings suggest that restaurant characteristics play a role in norovirus outbreak prevention and intervention; therefore, implementing food safety training, policies, and practices likely reduces norovirus transmission, leading to smaller or shorter outbreaks.