Burden of norovirus in healthcare facilities and strategies for outbreak control

Molecular Epidemiology of Human Norovirus Variants from Outbreaks in Zhejiang Province, China, during 2021

Background

Noroviruses are the most frequent cause of epidemic acute viral gastroenteritis in China.

Objectives

The aim of this study was to determine the molecular epidemiological characteristics of norovirus outbreaks and the molecular genetic features of norovirus in Zhejiang Province during 2021.

Methods

First, the local Centers for Disease Control and Prevention in the outbreak area conducted on-site epidemiologic investigations and collected samples from ill patients for initial testing. The general epidemiologic characteristics of the demographic information are presented through descriptive analysis. Positive samples were sent to the Microbiology Laboratory of Zhejiang Provincial Center for Disease Control and Prevention for further verification. The presence of norovirus genogroups I (GI) and II (GII), along with sapovirus, was detected. Subsequently, the specimens positive for norovirus were sequenced for genotyping purposes. Furthermore, the whole genomes of positive samples were sequenced, enabling the characterization of both nucleotide and amino acid differences within the virus. Finally, phylogenetic trees were constructed to further analyze and understand the genetic relationships among the detected viruses.

Result

227 norovirus outbreaks were reported in Zhejiang Province, China, during 2021. Schools were the main setting while January was the peak month for outbreaks. A total of 17 diverse genotypes of norovirus were identified in 2021, and GII.P16-GII.2 was the most frequent genotype (30.19%). Seven genomes (five GI.P4-GI.5 and two GII.P16-GII.2) were obtained. Although GI.P4-GI.5 is considered to be a rare genotype of norovirus, the prevalence might have been underestimated. Capsid microvariation of GII.2 displayed histo-blood group antigen binding patterns compared to the GII.2 prototype, although VP1 sequences were considered to have a minimal impact on antigenicity.

Conclusion

This study revealed the diversity of norovirus strains' genotypes circulating in Zhejiang Province in 2021. Continued molecular surveillance of noroviruses should be strengthened in our further efforts to the development of vaccines.

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.

A Prediction Tool to Identify the Causative Agent of Enteric Disease Outbreaks Using Outbreak Surveillance Data

Information on the causative agent in an enteric disease outbreak can be used to generate hypotheses about the route of transmission and possible vehicles, to guide environmental assessments, and to target outbreak control measures. However, only about 40% of outbreaks reported in the United States include a confirmed etiology. The goal of this project was to identify clinical and demographic characteristics that can be used to predict the causative agent in an enteric disease outbreak and to use these data to develop an online tool for investigators to use during an outbreak when hypothesizing about the causative agent. Using data on enteric disease outbreaks from all transmission routes (animal contact, environmental contamination, foodborne, person-to-person, waterborne, unknown) reported to the U.S. Centers for Disease Control and Prevention, we developed random forest models to predict the etiology of an outbreak based on aggregated clinical and demographic characteristics at both the etiology category (i.e., bacteria, parasites, toxins, viruses) and individual etiology (Clostridium perfringens, Campylobacter, Cryptosporidium, norovirus, Salmonella, Shiga toxin-producing Escherichia coli, and Shigella) levels. The etiology category model had a kappa of 0.85 and an accuracy of 0.92, whereas the etiology-specific model had a kappa of 0.75 and an accuracy of 0.86. The highest sensitivities in the etiology category model were for bacteria and viruses; all categories had high specificities (>0.90). For the etiology-specific model, norovirus and Salmonella had the highest sensitivity and all etiologies had high specificities. When laboratory confirmation is unavailable, information on the clinical signs and symptoms reported by people associated with the outbreak, with other characteristics including case demographics and illness severity, can be used to predict the etiology or etiology category. An online publicly available tool was developed to assist investigators in their enteric disease outbreak investigations.

Complex norovirus transmission dynamics at hospital wards revealed by deep sequencing

Detailed knowledge regarding norovirus transmission within hospitals is limited. We investigated a norovirus hospital outbreak affecting 65 patients at five different wards. PCR showed that 61 (94%) of the patients were infected with genotype II.4 strains. Successful Ion Torrent deep sequencing of GII.4 positive samples from 59 patients followed by phylogenetic analysis revealed that all sequences but two clustered into four distinct clades. Two of the clades belonged to GII.4 Sydney 2012, while the other two belonged to GII.4 New Orleans 2009. One of the clades was predominant at two wards, while two clades were predominant at one ward each. The fourth clade was found in sporadic cases at several wards. Thus, at four out of five wards, variants from one clade were predominant. At one ward, a single clade accounted for all cases, while at three wards the predominant clade accounted for 60%-71% of cases. Analysis of quasispecies variation identified positions that could further discriminate between variants from separate wards. The results illustrate a complex transmission of healthcare-associated norovirus infections and show that sequencing can be used to discriminate between related and unrelated cases.

Post-Acute and Long-Term Care Leaders' Perspectives on Leading During COVID-19

Post-acute and long-term care (PALTC) delivery is complex, and the COVID-19 pandemic created additional complexities. This qualitative study investigates how PALTC administrators responded to the pandemic, factors that impacted their leadership role and decision-making. Participants from North Carolina (N = 15) and Pennsylvania (N = 6) were interviewed using an interview guide containing open-ended questions. The results revealed three themes: (1) critical knowledge and competencies; (2) resources, supports and essential actions taken; and (3) psychosocial impact. The findings suggest communication and relationship building were the most useful competencies. Lack of staff was a primary stress point during and after the pandemic.

Metagenomic Surveillance of Viral Gastroenteritis in a Public Health Setting

Norovirus is the primary cause of viral gastroenteritis (GE). To investigate norovirus epidemiology, there is a need for whole-genome sequencing and reference sets consisting of complete genomes. To investigate the potential of shotgun metagenomic sequencing on the Illumina platform for whole-genome sequencing, 71 reverse transcriptase quantitative PCR (RT-qPCR) norovirus positive-feces (threshold cycle [CT], <30) samples from norovirus surveillance within The Netherlands were subjected to metagenomic sequencing. Data were analyzed through an in-house next-generation sequencing (NGS) analysis workflow. Additionally, we assessed the potential of metagenomic sequencing for the surveillance of off-target viruses that are of importance for public health, e.g., sapovirus, rotavirus A, enterovirus, parechovirus, aichivirus, adenovirus, and bocaparvovirus. A total of 60 complete and 10 partial norovirus genomes were generated, representing 7 genogroup I capsid genotypes and 12 genogroup II capsid genotypes. In addition to the norovirus genomes, the metagenomic approach yielded partial or complete genomes of other viruses for 39% of samples from children and 6.7% of samples from adults, including adenovirus 41 (N = 1); aichivirus 1 (N = 1); coxsackievirus A2 (N = 2), A4 (N = 2), A5 (N = 1), and A16 (N = 1); bocaparvovirus 1 (N = 1) and 3 (N = 1); human parechovirus 1 (N = 2) and 3 (N = 1); Rotavirus A (N = 1); and a sapovirus GI.7 (N = 1). The sapovirus GI.7 was initially not detected through RT-qPCR and warranted an update of the primer and probe set. Metagenomic sequencing on the Illumina platform robustly determines complete norovirus genomes and may be used to broaden gastroenteritis surveillance by capturing off-target enteric viruses. IMPORTANCE Viral gastroenteritis results in significant morbidity and mortality in vulnerable individuals and is primarily caused by norovirus. To investigate norovirus epidemiology, there is a need for whole-genome sequencing and reference sets consisting of full genomes. Using surveillance samples sent to the Dutch National Institute for Public Health and the Environment (RIVM), we compared metagenomics against conventional techniques, such as RT-qPCR and Sanger-sequencing, with norovirus as the target pathogen. We determined that metagenomics is a robust method to generate complete norovirus genomes, in parallel to many off-target pathogenic enteric virus genomes, thereby broadening our surveillance efforts. Moreover, we detected a sapovirus that was not detected by our validated gastroenteritis RT-qPCR panel, which exemplifies the strength of metagenomics. Our study shows that metagenomics can be used for public health gastroenteritis surveillance, the generation of reference-sets for molecular epidemiology, and how it compares to current surveillance strategies.

Antiviral Activity of Active Materials: Standard and Finger-Pad-Based Innovative Experimental Approaches

Environmental surfaces, including high-touch surfaces (HITS), bear a high risk of becoming fomites and can participate in viral dissemination through contact and transmission to other persons, due to the capacity of viruses to persist on such contaminated surface before being transferred to hands or other supports at sufficient concentration to initiate infection through direct contact. Interest in the development of self-decontaminating materials as additional safety measures towards preventing viral infectious disease transmission has been growing. Active materials are expected to reduce the viral charge on surfaces over time and consequently limit viral transmission capacity through direct contact. In this study, we compared antiviral activities obtained using three different experimental procedures by assessing the survival of an enveloped virus (influenza virus) and non-enveloped virus (feline calicivirus) over time on a reference surface and three active materials. Our data show that experimental test conditions can have a substantial impact of over 1 log₁₀ on the antiviral activity of active material for the same contact period, depending on the nature of the virus. We then developed an innovative and reproducible approach based on finger-pad transfer to evaluate the antiviral activity of HITS against a murine norovirus inoculum under conditions closely reflecting real-life surface exposure.

Norovirus: An Overview of Virology and Preventative Measures

Norovirus (NoV) is an enteric non-enveloped virus which is the leading cause of gastroenteritis across all age groups. It is responsible for around 200,000 deaths annually and outbreaks are common in small communities such as educational and care facilities. 40% of all NoV outbreaks occur in long-term and acute-care facilities, forming the majority of outbreaks. Nosocomial settings set ideal environments for ease of transmission, especially due to the presence of immunocompromised groups. It is estimated to cost global economies around £48 billion a year, making it a global issue. NoV is transmitted via the faecal-oral route and infection with it results in asymptomatic cases or gastrointestinal disease. It has high mutational rates and this allows for new variants to emerge and be more resistant. The classification system available divides NoV into 10 genogroups and 49 genotypes based on whole amino acid sequencing of VP1 capsid protein and partial sequencing of RdRp, respectively. The most predominant genotypes which cause gastroenteritis in humans include GI.1 and GII.4, where GII.4 is responsible for more extreme clinical implications such as hospitalisation. In addition, GII.4 has been responsible for 6 pandemic strains, the last of which is the GII.4 Sydney (2012) variant. In recent years, the successful cultivation of HuNoV was reported in stem cell-derived human intestinal enteroids (HIEs), which promises to assist in giving a deeper understanding of its underlying mechanisms of infection and the development of more personalized control measures. There are no specific control measures against NoV, therefore common practices are used against it such as hand washing. No vaccine is available, but the HIL-214 candidate passed clinical phase 2b and shows promise.

The Potential Antiviral Effects of Selenium Nanoparticles and Coated Surfaces

Modern epidemics quickly spread across borders and continents with devastating effects on both human health and the world economy. This issue is made worse by the various ways that infections are spread, including through aerosol, droplets, and fomites. The antibacterial qualities of various surface materials and coatings have been the subject of much research. However, the antiviral activity of metal coatings can be heavily influenced by imbalances in metal distribution and the presence of other metal impurities. As such, there is interest in developing novel surface coatings that can reduce the transmission of active viral particles in healthcare facilities. In recent years, the non-metals, such as selenium and nanoparticles, have acquired greater interest from the medical and scientific community for their antiviral surface activity. In this review, we will discuss the cellular and physiological functions of selenium in mammalian cells and against viral infections. We then discuss the mechanism behind selenium coated surfaces and their efficacy against bacterial infections. Lastly, we examine the antiviral activity of selenium, and the potential antiviral activity of selenium nanoparticles and coatings.

Lignin: A Sustainable Antiviral Coating Material

Transmission of viruses through contact with contaminated surfaces is an important pathway for the spread of infections. Antiviral surface coatings are useful to minimize such risks. Current state-of-the-art approaches toward antiviral surface coatings either involve metal-based materials or complex synthetic polymers. These approaches, however, even if successful, will have to face great challenges when it comes to large-scale applications and their environmental sustainability. Here, an antiviral surface coating was prepared by spin-coating lignin, a natural biomass residue of the paper production industry. We show effective inactivation of herpes simplex virus type 2 (>99% after 30 min) on a surface coating that is low-cost and environmentally sustainable. The antiviral mechanism of the lignin surface was investigated and is attributed to reactive oxygen species generated upon oxidation of lignin phenols. This mechanism does not consume the surface coating (as opposed to the release of a specific antiviral agent) and does not require regeneration. The coating is stable in ambient conditions, as demonstrated in a 6 month aging study that did not reveal any decrease in antiviral activity. This research suggests that natural compounds may be used for the development of affordable and sustainable antiviral coatings.

Amine-Functionalized Silver Nanoparticles: A Potential Antiviral-Coating Material with Trap and Kill Efficiency to Combat Viral Dissemination (COVID-19)

The outbreak of COVID-19 has drastically affected the daily lifestyles of people globally where specific Coronavirus-2 transmits primarily by respiratory droplets. Structurally, the SARS-CoV-2 virus is made up of four types of proteins in which S-protein is indispensable among them, as it causes rapid replication in the host body. Therefore, the glycine and alanine composed of HR1 of S-protein is the ideal target for antiviral action. Different forms of surface-active PPEs can efficiently prevent this transmission in this circumstance. However, the virus can survive on the conventional PPEs for a long time. Hence, the nanotechnological approaches based on engineered nanomaterials coating on medical equipments can potentially prevent the dissemination of infections in public. Silver nanoparticles with tuneable physicochemical properties and versatile chemical functionalization provide an excellent platform to combat the disease. The coating of amine-functionalized silver nanoparticle (especially amine linked to aliphatic chain and trialkoxysilane) in its nanostructured form enables cloths trap and kill efficient. PPEs are a primary and reliable preventive measure, although they are not 100% effective against viral infections. So, developing and commercializing surface-active PPEs with trap and kill efficacy is highly needed to cope with current and future viral infections. This review article discusses the COVID-19 morphology, antiviral mechanism of Ag-NPs against SARS-CoV-2 virus, surface factors that influence viral persistence on fomites, the necessity of antiviral PPEs, and the potential application of amine-functionalized silver nanoparticles as a coating material for the development of trap and kill-efficient face masks and PPE kits.

Shielding Surfaces from Viruses and Bacteria with a Multiscale Coating

The spread of viral and bacterial pathogens mediated by contact with surfaces is a leading cause of infection worldwide. COVID-19 and the continuous rise of deaths associated with antibiotic-resistant bacteria highlight the need to impede surface-mediated transmission. A sprayable coating with an intrinsic ability to resist the uptake of bacteria and viruses from surfaces and droplets, such as those generated by sneezing or coughing, is reported. The coating also provides an effective microbicidal functionality against bacteria, providing a dual barrier against pathogen uptake and transmission. This antimicrobial functionality is fully preserved following scratching and other induced damage to its surface or 9 days of submersion in a highly concentrated suspension of bacteria. The coatings also register an 11-fold decrease in viral contamination compared to the noncoated surfaces.

Nanoparticle Engineered Photocatalytic Paints: A Roadmap to Self-Sterilizing against the Spread of Communicable Diseases

Applications of visible-light photocatalytic engineered nanomaterials in the preparation of smart paints are of recent origin. The authors have revealed a great potential of these new paints for self-sterilizing of the surfaces in hospitals and public places simply with visible light exposure and this is reported for the first time in this review. A recent example of a communicable disease such as COVID-19 is considered. With all precautions and preventions taken as suggested by the World Health Organization (WHO), COVID-19 has remained present for a longer time compared to other diseases. It has affected millions of people worldwide and the significant challenge remains of preventing infections due to SARS-CoV-2. The present review is focused on revealing the cause of this widespread disease and suggests a roadmap to control the spread of disease. It is understood that the transmission of SARS-CoV-2 virus takes place through contact surfaces such as doorknobs, packaging and handrails, which may be responsible for many preventable and nosocomial infections. In addition, due to the potent transmissibility of SARS-CoV-2, its ability to survive for longer periods on common touch surfaces is also an important reason for the spread of COVID-19. The existing antimicrobial cleaning technologies used in hospitals are not suitable, viable or economical to keep public places free from such infections. Hence, in this review, an innovative approach of coating surfaces in public places with visible-light photocatalytic nanocomposite paints has been suggested as a roadmap to self-sterilizing against the spread of communicable diseases. The formulations of different nanoparticle engineered photocatalytic paints with their ability to destroy pathogens using visible light, alongwith the field trials are also summarized and reported in this review. The potential suggestions for controlling the spread of communicable diseases are also listed at the end of the review.

Norovirus Outbreaks in Long-term Care Facilities in the United States, 2009-2018: A Decade of Surveillance

BACKGROUND

In the United States, norovirus is the leading cause of healthcare-associated gastroenteritis outbreaks. To inform prevention efforts, we describe the epidemiology of norovirus outbreaks in long-term care facilities (LTCFs).

METHODS

The Centers for Disease Control and Prevention (CDC) collect epidemiologic and laboratory data on norovirus outbreaks from US health departments through the National Outbreak Reporting System (NORS) and CaliciNet. Reports from both systems were merged, and norovirus outbreaks in nursing homes, assisted living, and other LTCFs occurring in 2009-2018 were analyzed. Data from the Centers for Medicare and Medicaid Services and the National Center for Health Statistics were used to estimate state LTCF counts.

RESULTS

During 2009-2018, 50 states, Washington D.C., and Puerto Rico reported 13 092 norovirus outbreaks and 416 284 outbreak-associated cases in LTCFs. Participation in NORS and CaliciNet increased from 2009 to 2014 and median reporting of LTCF norovirus outbreaks stabilized at 4.1 outbreaks per 100 LTCFs (interquartile range [IQR]: 1.0-7.1) annually since 2014. Most outbreaks were spread via person-to-person transmission (90.4%), and 75% occurred during December-March. Genogroup was reported for 7292 outbreaks with 862 (11.8%) positive for GI and 6370 (87.3%) for GII. Among 4425 GII outbreaks with typing data, 3618 (81.8%) were GII.4. LTCF residents had higher attack rates than staff (median 29.0% vs 10.9%; P < .001). For every 1000 cases, there were 21.6 hospitalizations and 2.3 deaths.

CONCLUSIONS

LTCFs have a high burden of norovirus outbreaks. Most LTCF norovirus outbreaks occurred during winter months and were spread person-to-person. Outbreak surveillance can inform development of interventions for this vulnerable population, such as vaccines targeting GII.4 norovirus strains.

Norovirus disease among older adults

Norovirus, a leading cause of gastroenteritis outbreaks worldwide, results in substantial direct and indirect healthcare costs. Adults older than 65 years of age bear a significant proportion of the disease burden, and the disease course in this population is often more severe and protracted. In this narrative review, we discuss the epidemiology of norovirus infection, mechanisms of pathogenesis, and transmission pertinent to outbreaks along with infection prevention and control efforts. We also describe the clinical manifestations of norovirus disease with a focus on individuals older than 65 years of age, diagnosis and available treatment options, and the challenges and progress within vaccine development.

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.

Antigenic cartography reveals complexities of genetic determinants that lead to antigenic differences among pandemic GII.4 noroviruses

Noroviruses are the predominant cause of acute gastroenteritis, with a single genotype (GII.4) responsible for the majority of infections. This prevalence is characterized by the periodic emergence of new variants that present substitutions at antigenic sites of the major structural protein (VP1), facilitating escape from herd immunity. Notably, the contribution of intravariant mutations to changes in antigenic properties is unknown. We performed a comprehensive antigenic analysis on a virus-like particle panel representing major chronological GII.4 variants to investigate diversification at the inter- and intravariant level. Immunoassays, neutralization data, and cartography analyses showed antigenic similarities between phylogenetically related variants, with major switches to antigenic properties observed over the evolution of GII.4 variants. Genetic analysis indicated that multiple coevolving amino acid changes-primarily at antigenic sites-are associated with the antigenic diversification of GII.4 variants. These data highlight complexities of the genetic determinants and provide a framework for the antigenic characterization of emerging GII.4 noroviruses.

Risk of environmental transmission of norovirus infection from prior room occupants

BACKGROUND

Environmental contamination of norovirus (NoV) is believed to be a significant source for further transmission in hospitals.

AIM

To investigate the risk of acquiring NoV in a cleaned room previously occupied by a patient with NoV infection. The risk of having a roommate with recent NoV infection was also assessed.

METHODS

In a retrospective cohort, comprising 33,788 room stays at five infectious Disease wards in southern Sweden from 2013 to 2018, the risk of acquiring NoV infection after admission to an exposed or non-exposed room was analysed with uni- and multivariable statistical analysis, controlling for age, colonization pressure and any roommate. RNA sequencing of the NoV strains involved in suspected room transmission was also performed.

RESULTS

Five of the 1106 patients exposed to a room with a prior occupant with NoV infection and 49 in the non-exposed group acquired NoV infection. An association between NoV acquisition was found in the univariable analysis (odds ratio (OR) 3.3, P=0.01), but not when adjusting for potential confounders (OR 1.9, P=0.2). Sequencing of the NoV samples showed that only two of the five exposed patients with acquired NoV infection were infected by identical strains to the prior room occupant, inferring a room transmission risk of 0.2% (95% confidence interval 0.05-0.78%). None of the 52 patients who shared room with a roommate with NoV symptoms resolved for ≥48 h acquired NoV infection.

CONCLUSIONS

In absolute terms, the risk of room transmission of NoV is low. Discontinuation of isolation ≥48 h after resolution of symptoms seems adequate.

Outbreaks in Health Care Settings

Outbreaks and pseudo-outbreaks in health care settings are complex and should be evaluated systematically using epidemiologic and molecular tools. Outbreaks result from failures of infection prevention practices, inadequate staffing, and undertrained or overcommitted health care personnel. Contaminated hands, equipment, supplies, water, ventilation systems, and environment may also contribute. Neonatal intensive care, endoscopy, oncology, and transplant units are areas at particular risk. Procedures, such as bronchoscopy and endoscopy, are sources of infection when cleaning and disinfection processes are inadequate. New types of equipment can be introduced and lead to contamination or equipment and medications can be contaminated at the manufacturing source.

Long-term dynamics of Norovirus transmission in Japan, 2005-2019

Norovirus continues to evolve, adjusting its pathogenesis and transmissibility. In the present study, we systematically collected datasets on Norovirus outbreaks in Japan from 2005 to 2019 and analyzed time-dependent changes in the asymptomatic ratio, the probability of virus detection, and the probability of infection given exposure. Reports of 1,728 outbreaks were published, and feces from all involved individuals, including those with asymptomatic infection, were tested for virus in 434 outbreaks. We found that the outbreak size did not markedly change over this period, but the variance in outbreak size increased during the winter (November–April). Assuming that natural history parameters did not vary over time, the asymptomatic ratio, the probability of virus detection, and the probability of infection given exposure were estimated to be 18.6%, 63.3% and 84.5%, respectively. However, a model with time-varying natural history parameters yielded better goodness-of-fit and suggested that the asymptomatic ratio varied by year. The asymptomatic ratio was as high as 25.8% for outbreaks caused by genotype GII.4 noroviruses. We conclude that Norovirus transmissibility has not changed markedly since 2005, and that yearly variation in the asymptomatic ratio could potentially be explained by the circulating dominant genotype.

Factors associated with the detection of norovirus among asymptomatic adults

OBJECTIVES

Little is known about asymptomatic norovirus infection and its risk factors in healthy adults. This study investigated detection of norovirus in stool and its associated factors among asymptomatic healthy adults in a high-income country.

METHODS

This prospective cross-sectional study-conducted between February 2016 and January 2017 at a teaching hospital in Japan-included apparently healthy adults aged ≥18 years who underwent voluntary health check-ups. Our primary outcome was detection of norovirus in stool specimens confirmed by real-time RT-PCR. We evaluated descriptive statistics and associated factors, including demographics, social habits, and clinical parameters.

RESULTS

Among 15 532 participants, 4536 (29.2%, mean age 58.0 (standard deviation 11.8) years, male 44.6%) were enrolled, and 112 (2.5%, GI 57, GII 54, GI + GII 1) were norovirus-positive. Monthly prevalence rates of the GI norovirus were consistent throughout the year, while those of GII were high in May. Participants aged <40 and ≥ 80 years had higher rates of GII norovirus detection. Participants who occasionally consume alcohol, especially wine (odds ratio (OR) 0.17, 95% confidence interval (CI) 0.04-0.68), had lower norovirus detection rates than abstainers. Participants with untreated dyslipidaemia and a low high-density lipoprotein (HDL) cholesterol level had higher detection rates than those with treated dyslipidaemia (OR 1.48, 95%CI 1.07-2.05) and a normal HDL cholesterol level (OR 2.60, 95%CI 1.46-4.61). Some gastrointestinal and female genital diseases were associated with norovirus detection.

CONCLUSIONS

The norovirus detection rate in asymptomatic adults was 2.5%. Participants with specific lifestyles or medical histories may have higher risks of asymptomatic norovirus infection.

Healthcare associated diarrhea, not Clostridioides difficile

PURPOSE OF REVIEW

The aim of this article is to review the epidemiology, cause, diagnostic evaluation, and management of healthcare-associated diarrhea (HCAD) with particular attention to current epidemiology and recent developments in diagnostics.

RECENT FINDINGS

Multiplex polymerase chain reaction gastrointestinal panels allow rapid detection of a wide array of potential enteropathogens but the role, yield, and utility of these tests have not been systematically assessed in patients with HCAD. Recent epidemiologic studies reaffirm that HCAD is predominantly a noninfectious condition most often caused by medications or underlying medical conditions, sometimes Clostridioides difficile, and occasionally viruses. Other infections are rare.

SUMMARY

Clinical assessment remains fundamental to the evaluation of HCAD and targeted testing for C. difficile is sufficient in most patients. Multiplex gastrointestinal panels may have a role in immunocompromised patients but more study is needed. Medication-induced diarrhea is common and underappreciated and not limited to antibiotics, laxatives, and enemas.

Global prevalence and genotype distribution of norovirus infection in children with gastroenteritis: A meta-analysis on 6 years of research from 2015 to 2020

In the post rotavirus vaccine era, norovirus (NoV) plays an increasingly important role in epidemic and sporadic gastroenteritis among children. This study was designed to provide an updated meta-analytic review of the prevalence of NoV among paediatric patients with gastroenteritis and to clarify the relationship between NoV infection and gastroenteritis. Systematic searches of the literature for potentially relevant studies were carried out from 1 January 2015 to 29 May 2020. The inverse variance method was chosen for weighting of the studies, and the random-effects model was used to analyse data. To determine the association between NoV infection and gastroenteritis in children, pooled odds ratio (OR) and its 95% confidence interval (CI) were computed for case-control studies. The pooled prevalence of NoV infection among 12,0531 children with gastroenteritis from 45 countries across the world was 17.7% (95% CI: 16.3%-19.2%). There were 28 studies with a case-control design, and the pooled prevalence of NoV infection among 11,954 control subjects was 6.7% (95% CI: 5.1%-8.8%). The pooled OR of the association of NoV infection and gastroenteritis was 2.7 (95% CI: 2.2-3.4). The most common NoV genotypes were GII.4 (59.3%) and GII.3 (14.9%). The highest frequency of NoV was found in the age group below 1 year. Our findings indicated a substantial burden of gastroenteritis caused by NoV globally, with GII.4 and GII.3 the major genotypes responsible for the majority of NoV-associated gastroenteritis cases among children. Younger age and male sex can be considered risk factors for NoV-associated gastroenteritis among children.

Association of environmental surface contamination with hand hygiene and infections in nursing homes: a prospective cohort study

Background

Little is known about the presence of infections in nursing home residents, the causative micro-organisms, how hand hygiene (HH) influences the presence of infections in residents, and the extent to which environmental contamination is associated with the incidence of infection among residents.

Aims

To establish if environmental contamination can be used as an indicator for HH compliance, and if environmental contamination is associated with the incidence of infection.

Methods

Environmental surface samples (ESS) were collected in an exploratory study as part of a HH intervention in 60 nursing homes. ESS results from three distinct surfaces (nurses' station, communal toilet and residents' shared living area) were compared with nurses' HH compliance and the incidence of infection among residents. Real-time polymerase chain reaction assays were used to detect norovirus genogroup I and II, rhinovirus and Escherichia coli. HH compliance was measured by direct observation. The incidence of infection was registered weekly.

Findings

Rhinovirus (nurses' station: 41%; toilet: 14%; living area: 29%), norovirus (nurses' station: 18%; toilet: 12%; living area: 16%) and E. coli (nurses' station: 14%; toilet: 58%; living area: 54%) were detected. No significant (P<0.05) associations were found between HH compliance and the presence of micro-organisms. An association was found between E. coli contamination and the incidence of disease in general (P=0.04). No other associations were found between micro-organisms and the incidence of disease.

Conclusion

Rhinovirus, norovirus and E. coli were detected on surfaces in nursing homes. No convincing associations were found between environmental contamination and HH compliance or the incidence of disease. This study provides reference data about surface contamination.

Differences in Illness Severity among Circulating Norovirus Genotypes in a Large Pediatric Cohort with Acute Gastroenteritis

Norovirus is a major pathogen identified in children with acute gastroenteritis (AGE), little is known about the strain's diversity and their clinical severity. Stool and/or rectal swabs were collected from children ≤18 years of age recruited at emergency departments (ED), and a provincial nursing advice phone line due to AGE symptoms in the province of Alberta, Canada between December 2014 and August 2018. Specimens were tested using a reverse transcription real time PCR and genotyped by Sanger sequencing. The Modified Vesikari Scale score (MVS) was used to evaluate the disease severity. The objectives are to identify the Genogroup and Genotype distribution and to compare illness severity between the GI and GII genogroups and to complete further analyses comparing the GII genotypes identified. GII.4 was the genotype most commonly identified. Children with GII.4 had higher MVS scores (12.0 (10.0, 14.0; p = 0.002)) and more prolonged diarrheal (5 days (3.0, 7.8)) and vomiting (3.2 days (1.7, 5.3; p < 0.001)) durations compared to other non GII.4 strains. The predominant strain varied by year with GII.4 Sydney[P31] predominant in 2014/15, GII.4 Sydney[P16] in 2015/16 and 2017/18, and GII.3[P12] in 2016/17. Genogroup II norovirus strains predominated in children with AGE with variance between years; clinical severity associated with different strains varied with episodes being most severe among GII.4 infected children.

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-NoV outbreaks (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.

The use of military planning techniques to manage outbreaks of novel infections in acute inpatient settings: development of an 'infection control estimate' (ICE)

Outbreaks of infection create unique challenges to healthcare leaders and members of infection control teams who lead efforts to manage, control and resolve outbreaks. This is especially true during outbreaks of novel pathogens which may require atypical control methods reflecting the unknowns inherent in such situations. Healthcare providers within the UK have adopted various structures and models of infection prevention and control (IPC) service reflecting the individual needs of different organisations. As such, the roles and responsibilities of IPC practitioners vary between organisations. Variations in models of care combined with challenges created by outbreaks of novel infections may make algorithm based approaches to outbreak management less effective and potentially prone to missing key actions or considerations which may improve outcomes. Here we suggest the application of a widely established military planning technique, developed to aid decision making in combat environments, to the management of outbreaks of novel infection in acute hospital settings. The technique can be applied at all levels within an IPC hierarchy regardless of role or responsibility and may improve the coherency and efficacy of outbreak management efforts made by IPC teams. The technique may also be applied to outbreaks of known infections; however, in order to demonstrate the flexibility of the model, a novel infection has been used to illustrate its potential value in outbreak management when knowledge is limited.

Norovirus outbreaks on college and university campuses

Objective: To describe norovirus outbreaks at colleges and universities. Participants: None. Conducted September 2016 to March 2018. Methods: College and university norovirus outbreaks reported to the US National Outbreak Reporting System (NORS, 2009-2016) or published and indexed by EMBASE, PubMed, and Web of Science (1985-2017) were analyzed. Results: Seventy-seven norovirus outbreaks were reported to NORS and 23 were identified in the systematic literature review. Outbreaks occurred more frequently during the beginning of the school year (September-February). NORS outbreaks were more often spread by person-to-person transmission (61%) and, in published outbreaks, by food (57%). The reported exposures of published outbreaks were campus dining (n = 8) and ill food service workers (n = 7). Higher attack rates were associated with smaller on-campus population size, social networks or residences, and specific food exposures. Common control measures were communal area disinfection and health/hygiene education. Conclusions: Recommendations summarized to prevent and control norovirus outbreaks at colleges or universities.

Rapid detection of norovirus genogroup II in clinical and environmental samples using recombinase polymerase amplification

Norovirus is the leading cause of acute gastroenteritis all over the world, and the most genotype that causes its epidemic is norovirus genogroup II (NoVs GII). Rapid detection of NoVs is important because it can facilitate timely diagnosis. In this study, we designed universal specific primers and an Exo probe to hybridize to all genetic clusters of NoVs GII based on the conserved region at the ORF1-ORF2 junction of the genome. For the first time, we established a rapid and reliable reverse transcription recombinase polymerase amplification (RT-RPA) method for the detection of NoVs GII within 20 min. This method can specifically amplify NoVs GII, and the detection limit was as low as 1.66 × 10² copies/μL. The method was validated in terms of LOD, accuracy, and specificity. We tested 55 real samples including foods, water, and feces. The results showed a sensitivity of 96% and specificity of 100% to NoVs GII. The whole procedure can be operated by a mobile suitcase laboratory, which is useful for resource-limited diagnostic laboratories. This novel real-time RT-RPA assay is an accurate tool for point-of-care testing of NoVs, providing practical support for norovirus-caused disease diagnosis and prevention.

Quantifying the roles of vomiting, diarrhea, and residents vs. staff in norovirus transmission in U.S. nursing home outbreaks

The role of individual case characteristics, such as symptoms or demographics, in norovirus transmissibility is poorly understood. Six nursing home norovirus outbreaks occurring in South Carolina, U.S. from 2014 to 2016 were examined. We aimed to quantify the contribution of symptoms and other case characteristics in norovirus transmission using the reproduction number (R_Ei) as an estimate of individual case infectivity and to examine how transmission changes over the course of an outbreak. Individual estimates of R_Ei were calculated using a maximum likelihood procedure to infer the average number of secondary cases generated by each case. The associations between case characteristics and R_Ei were estimated using a weighted multivariate mixed linear model. Outbreaks began with one to three index case(s) with large estimated R_Ei’s (range: 1.48 to 8.70) relative to subsequent cases. Of the 209 cases, 155 (75%) vomited, 164 (79%) had diarrhea, and 158 (76%) were nursing home residents (vs. staff). Cases who vomited infected 2.12 (95% CI: 1.68, 2.68) times the number of individuals as non-vomiters, cases with diarrhea infected 1.39 (95% CI: 1.03, 1.87) times the number of individuals as cases without diarrhea, and resident-cases infected 1.53 (95% CI: 1.15, 2.02) times the number of individuals as staff-cases. Index cases tended to be residents (vs. staff) who vomited and infected considerably more secondary cases compared to non-index cases. Results suggest that individuals, particularly residents, who vomit are more infectious and tend to drive norovirus transmission in U.S. nursing home norovirus outbreaks. While diarrhea also plays a role in norovirus transmission, it is to a lesser degree than vomiting in these settings. Results lend support for prevention and control measures that focus on cases who vomit, particularly if those cases are residents.

The majority of all norovirus outbreaks reported to the CDC occur in long-term care facilities (LTCFs), including nursing homes, where older residents are at risk for more severe or prolonged infection. Because there is currently no publicly available norovirus vaccine, sound control measures are key to controlling norovirus outbreaks, but there is little evidence that standard control measures are effective in reducing the size and/or duration of LTCF norovirus outbreaks. Hence, studies leading to a better understanding of disease spread and prevention of additional cases, and thus more effective control measures, are needed. To this end, we aimed to quantify factors associated with norovirus transmission and to examine how transmission changes over the course of an outbreak. We show that vomiting and, to a lesser extent, diarrhea are critical in initiating and sustaining norovirus transmission in U.S. nursing home norovirus outbreaks. We also show that nursing home residents, rather than staff, are the primary drivers of transmission. Results suggest that control measures focusing on cases who vomit, particularly if those cases are residents, would be most effective at curtailing norovirus transmission in these settings.

Performance of the QIAstat-Dx Gastrointestinal Panel for Diagnosing Infectious Gastroenteritis

Detection and identification of enteropathogens that cause infectious gastroenteritis are essential steps for appropriate patient treatment and effective isolation precautions. Several syndrome-based tests have recently become available, with the gastrointestinal panel (GIP) assay on the QIAstat-Dx as the most recent addition to the syndromic testing landscape.

Detection and identification of enteropathogens that cause infectious gastroenteritis are essential steps for appropriate patient treatment and effective isolation precautions. Several syndrome-based tests have recently become available, with the gastrointestinal panel (GIP) assay on the QIAstat-Dx as the most recent addition to the syndromic testing landscape. The QIAstat-Dx GIP assay offers simultaneous testing for 24 bacterial, viral, and parasitic enteropathogens using a single test that reports the results in 70 min. In this study, we compared the performance of the GIP assay to laboratory-developed real-time PCR assays (LDTs), using 172 prospectively and retrospectively collected fecal samples from patients suspected to have infectious gastroenteritis. The GIP assay detected 97/107 enteropathogens (91%) that were detected by LDTs, and the overall agreement of results increased to 95% when excluding discrepant results with cycle threshold (C_T) values of >35. Further, the GIP assay detected 42 additional enteropathogens that were not detected, or tested, by LDTs. These included 35 diarrheagenic Escherichia coli targets for which the clinical relevance is unclear for most. The main advantage of the QIAstat-Dx system compared to other syndromic testing systems is the ability to generate C_T values that could help with the interpretation of results. However, compared to LDTs, the GIP assay is limited by flexibility and high-throughput testing. In conclusion, the GIP assay offers an easy, sample-to-answer workflow with a rapid detection of the most common enteropathogens and therefore has the potential to direct appropriate therapy and infection control precautions.

[On Statistical Underreporting of Norovirus-Infections: Insights from Register Data of Two Local Public Health Authorities]

BACKGROUND

Only laboratory-confirmed norovirus (NoV) cases have to be notified to the Robert Koch Institute (RKI) since 2011, but not other, e. g. clinical-epidemiological cases. It can be assumed that the extent of underreporting of NoV cases in Germany has significantly increased since then.

OBJECTIVES

To discuss the extent of underreporting, we wanted to find out how many laboratory tests were carried out during gastroenteritis outbreaks. Furthermore, the significance of NoV outbreaks in occupational health is discussed.

MATERIALS AND METHODS

Of all pseudonymized gastroenteritis outbreak data reported to 2 local health authorities between 2011 and 2015, the proportion of NoV outbreaks and reported cases of infection among employees in hospitals and community facilities (nursing homes for the elderly, day-care centers, schools) confirmed by laboratory tests was calculated retrospectively.

RESULTS

Only a few gastroenteritis outbreaks in day-care centers were etiologically diagnosed, so that only 6% and less could be classified as NoV outbreaks. In nursing homes for the elderly, about half of the outbreaks were classified as NoV, in hospitals almost all of them. Employees accounted for up to 23% of those affected in NoV outbreaks.

CONCLUSIONS

The low level of laboratory diagnostics carried out during gastroenteritis outbreaks in day-care centers suggests a considerable number of hidden NoV cases. The significant proportion of staff relative to the total number of infected persons during the outbreaks highlights the importance of the burden of NoV outbreaks as a topic in occupational health. Further, large-scale prospective studies are needed to empirically substantiate these initial findings.

The Norovirus Epidemiologic Triad: Predictors of Severe Outcomes in US Norovirus Outbreaks, 2009-2016

BACKGROUND

Noroviruses are the leading cause of acute gastroenteritis outbreaks worldwide. Clarifying the viral, host, and environmental factors (epidemiologic triad) associated with severe outcomes can help target public health interventions.

METHODS

Acute norovirus outbreaks reported to the National Outbreak Reporting System (NORS) in 2009-2016 were linked to laboratory-confirmed norovirus outbreaks reported to CaliciNet. Outbreaks were analyzed for differences in genotype (GII.4 vs non-GII.4), hospitalization, and mortality rates by timing, setting, transmission mode, demographics, clinical symptoms, and health outcomes.

RESULTS

A total of 3747 norovirus outbreaks were matched from NORS and CaliciNet. Multivariable models showed that GII.4 outbreaks (n = 2353) were associated with healthcare settings (odds ratio [OR], 3.94 [95% confidence interval {CI}, 2.99-5.23]), winter months (November-April; 1.55 [95% CI, 1.24-1.93]), and older age of cases (≥50% aged ≥75 years; 1.37 [95% CI, 1.04-1.79]). Severe outcomes were more likely among GII.4 outbreaks (hospitalization rate ratio [RR], 1.54 [95% CI, 1.23-1.96]; mortality RR, 2.77 [95% CI, 1.04-5.78]). Outbreaks in healthcare settings were also associated with higher hospitalization (RR, 3.22 [95% CI, 2.34-4.44]) and mortality rates (RR, 5.65 [95% CI, 1.92-18.70]).

CONCLUSIONS

Severe outcomes more frequently occurred in norovirus outbreaks caused by GII.4 and those in healthcare settings. These results should help guide preventive interventions for targeted populations, including vaccine development.

Lessons learned from a prolonged norovirus GII.P16-GII.4 Sydney 2012 variant outbreak in a long-term care facility in Portugal, 2017

OBJECTIVE

To investigate an outbreak of acute gastroenteritis caused by norovirus (NoV) in a long-term care facility (LTCF) in Portugal to describe and estimate its extent, and we implemented control measures.

DESIGN

Outbreak investigation.

METHODS

Probable cases were residents or staff members in the LTCF with at least 1 of the following symptoms: (1) diarrhea, (2) vomiting, (3) nausea, and/or (4) abdominal pain between October 31 and December 8, 2017. Confirmed cases were probable cases with positive NoV infection detected by real-time polymerase chain reaction (RT-PCR) and the same genotype in stool specimens.

RESULTS

The outbreak was caused by NoV GII.P16-GII.4 Sydney 2012 variant and affected 146 people. The highest illness rates were observed in residents (97 of 335, 29%) and nurses (16 of 83, 19%). All 11 resident wards were affected. Data on cases and their working or living areas suggest that movement between wards facilitated the transmission of NoV, likely from person to person.

CONCLUSIONS

The delay in the identification of the causative agent, a lack of restrictions of resident and staff movement between wards, and ineffective initial deep-cleaning procedures resulted an outbreak that continued for >1 month. The outbreak ended only after implementation of strict control measures. Recommendations for controlling future NoV outbreaks in LTCFs include emphasizing the need to control resident's movements and to restrict visitors, timely and effective environmental cleaning and disinfection, leave of absence for ill staff, and encouraging effective hand hygiene.

Molecular Dynamics Studies of Histo-Blood Group Antigen Blocking Human Immunoglobulin A Antibody and Escape Mechanism in Noroviruses Upon Mutation

Norovirus is the causing agent of acute gastroenteritis disease globally. Efforts in developing therapeutics against virus infection mostly fail due to emergence of drug resistance that is a consequence of presence of high mutation rates in virus genome during virus' life cycle. In this study, we computationally analyzed the affinity of a drug target, wild type VP1 envelope protein and its three variants to a therapeutic antibody FAB5I2. We have found that mutations break important hydrogen bonds and cause high fluctuations in residues that form VP1-FAB5I2 complex interface. In addition to changes in dynamics, we also revealed that the affinity of FAB5I2 to VP1 protein drops significantly upon mutations in terms of relative binding free energy.

Estimating the Hospital Burden of Norovirus-Associated Gastroenteritis in England and Its Opportunity Costs for Nonadmitted Patients

Background

Norovirus places a substantial burden on healthcare systems, arising from infected patients, disease outbreaks, beds kept unoccupied for infection control, and staff absences due to infection. In settings with high rates of bed occupancy, opportunity costs arise from patients who cannot be admitted due to beds being unavailable. With several treatments and vaccines against norovirus in development, quantifying the expected economic burden is timely.

Methods

The number of inpatients with norovirus-associated gastroenteritis in England was modeled using infectious and noninfectious gastrointestinal Hospital Episode Statistics codes and laboratory reports of gastrointestinal pathogens collected at Public Health England. The excess length of stay from norovirus was estimated with a multistate model and local outbreak data. Unoccupied bed-days and staff absences were estimated from national outbreak surveillance. The burden was valued conventionally using accounting expenditures and wages, which we contrasted to the opportunity costs from forgone patients using a novel methodology.

Results

Between July 2013 and June 2016, 17.7% (95% confidence interval [CI], 15.6%‒21.6%) of primary and 23.8% (95% CI, 20.6%‒29.9%) of secondary gastrointestinal diagnoses were norovirus attributable. Annually, the estimated median 290000 (interquartile range, 282000‒297000) occupied and unoccupied bed-days used for norovirus displaced 57800 patients. Conventional costs for the National Health Service reached £107.6 million; the economic burden approximated to £297.7 million and a loss of 6300 quality-adjusted life-years annually.

Conclusions

In England, norovirus is now the second-largest contributor of the gastrointestinal hospital burden. With the projected impact being greater than previously estimated, improved capture of relevant opportunity costs seems imperative for diseases such as norovirus.

Epidemiologic characteristics of health care-associated outbreaks and lessons learned from multiple outbreak investigations with a focus on the usefulness of routine molecular analysis

BACKGROUND

Single outbreaks have often been reported in health care settings, but the frequency of outbreaks at a hospital over time has not been described. We examined epidemiologic features of all health care-associated outbreak investigations at an academic hospital during a 5-year period.

METHODS

Health care-associated outbreak investigations at an academic hospital (2012-2016) were retrospectively reviewed through data on comprehensive hospital-wide surveillance and pulsed-field gel electrophoresis (PFGE) analysis.

RESULTS

Fifty-one health care-associated outbreaks (annual range, 8-15), including 26 (51%) outbreaks in intensive care units (ICUs), and 263 infected-colonized patients involved in these outbreaks were identified. The frequency of pathogens varied by affected location, specifically multidrug-resistant organisms (20/26 outbreaks, 77% in ICUs vs 2/25 outbreaks, 8% in non-ICUs; P < .0001) and gastroenteritis because of Clostridium difficile, norovirus, or adenovirus (1/26 outbreaks, 4% in ICUs vs 17/25 outbreaks, 68% in non-ICUs; P < .0001). Outbreaks occurred in approximately one-third of all units (37%) with some repeated instances of the same pathogens. Of 16 outbreaks caused by a bacterial pathogen evaluated by PFGE, 12 (75%) included some indistinguishable strains, suggesting person-to-person transmission or a common source.

CONCLUSIONS

This study demonstrated epidemiologic characteristics of multiple outbreaks between ICUs and non-ICUs and the value of molecular typing in understanding the epidemiology of health care-associated outbreaks.

Molecular-Genetic Characterization of Human Rotavirus A Strains Circulating in Moscow, Russia (2009-2014)

Enteric viruses are the most common cause of acute gastroenteritis (AGE) in young children and a significant public health problem globally. Hospital admissions of children under 5 years of age with diarrhea are primarily associated with group A rotavirus (RVA) infection. In this retrospective study, the population structure of viruses linked to AGE etiology in young children hospitalized with AGE in Moscow was evaluated, and molecular characterization of RVA strains was performed. Fecal specimens were collected from children under 5 years old hospitalized with AGE between 2009 and 2014 in Moscow, Russia. Multiplex real-time reverse transcription PCR was used to detect enteric viruses and for G/[P]-genotyping of isolated RVAs. Sequencing of RVA VP7 and VP4 cDNA fragments was used to validate the data obtained by PCR-genotyping. The main causes for hospitalization of children with AGE were RVA (40.1%), followed by noroviruses (11.4%), while adenoviruses, astroviruses, sapoviruses, enteroviruses, and orthoreoviruses were detected in 4.7%, 1.9%, 1.4%, 1.2%, and 0.2% of samples tested, respectively. Nosocomial infections, predominantly associated with RVAs and noroviruses, were detected in 24.8% of cases and occurred significantly more frequently in younger infants. The predominant RVA genotype was G4P[8], detected in 38.7% of RVA-positive cases, whereas genotypes G1P[8], G9P[8], G3P[8], and G2P[4] were found in 11.8%, 6.6%, 4.2%, and 3.3% of cases, respectively. Together, the presence of circulating RVA strains with rare VP7 and VP4 gene variants (G6 and P[9]) highlights the need to conduct continuous epidemiological monitoring of RVA infection.

Role of viral bioaerosols in nosocomial infections and measures for prevention and control

The presence of patients with diverse pathologies in hospitals results in an environment that can be rich in various microorganisms including respiratory and enteric viruses, leading to outbreaks in hospitals or spillover infections to the community. All hospital patients are at risk of nosocomial viral infections, but vulnerable groups such as older adults, children and immuno-compromised/-suppressed patients are at particular risk of severe outcomes including prolonged hospitalization or death. These pathogens could transmit through direct or indirect physical contact, droplets or aerosols, with increasing evidence suggesting the importance of aerosol transmission in nosocomial infections of respiratory and enteric viruses. Factors affecting the propensity to transmit and the severity of disease transmitted via the aerosol route include the biological characteristics affecting infectivity of the viruses and susceptibility of the host, the physical properties of aerosol particles, and the environmental stresses that alter these properties such as temperature and humidity. Non-specific systematic and individual-based interventions designed to mitigate the aerosol route are available although empirical evidence of their effectiveness in controlling transmission of respiratory and enteric viruses in healthcare settings are sparse. The relative importance of aerosol transmission in healthcare setting is still an on-going debate, with particular challenge being the recovery of infectious viral bioaerosols from real-life settings and the difficulty in delineating transmission events that may also be a result of other modes of transmission. For the prevention and control of nosocomial infections via the aerosol route, more research is needed on identifying settings, medical procedures or equipment that may be associated with an increased risk of aerosol transmission, including defining which procedures are aerosol-generating; and on the effectiveness of systematic interventions on aerosol transmission of respiratory and enteric viruses in healthcare settings.

Pilot survey of norovirus in Northern Italy: an example of surveillance of norovirus gastroenteritis

In this study, we describe the results of virological investigations carried out on cases of gastroenteritis reported in different communities within a 2-year pilot surveillance programme (January 2012 to December 2013) in the autonomous province of Bolzano (Northern Italy). Among the 162 norovirus (NoV)-positive cases out of 702 cases investigated, 76 were grouped in nine suspected outbreaks, 37 were hospital-acquired and 49 were community-acquired sporadic cases. NoV infections were found in all age groups in outbreak and community-acquired cases, while the highest peak of hospital-acquired infections occurred in the elderly. Sequence analyses helped to identify suspected outbreaks both in the community and in hospital wards. Although GII.4 is the predominant genotype, sequence data confirmed that at least seven genotypes circulate causing sporadic cases. Findings in this study confirmed the relevance of NoV infections as a cause of outbreaks, and impact of NoV infections in community-acquired sporadic cases in adults that are rarely described because of a lack of reporting.

Norovirus and Clostridium difficile outbreaks: squelching the wildfire

PURPOSE OF REVIEW

Gastrointestinal outbreaks in the healthcare setting cause increased morbidity and mortality in an already vulnerable population. Optimization of infection prevention measures can be a challenge in healthcare settings. This review describes new literature that may change the traditional infection prevention approach to such outbreaks.

RECENT FINDINGS

Asymptomatic carriers of both norovirus and Clostridium difficile can pose risk of transmission to others and the environment. Rapid recognition and diagnosis can decrease the extent of an outbreak. No-touch technologies for environmental disinfection are new and effective tools. Infection prevention consultant services and systems redesign can augment efforts to control baseline infection rates and outbreaks. Antimicrobial stewardship continues to be essential to prevent C. difficile infection.

SUMMARY

New approaches are needed to stem the tide of norovirus and C. difficile clusters and outbreaks in healthcare settings. Accurate recognition, testing, and implementation of infection prevention measures can be supported with rapid testing modalities, access to updated guidelines and no-touch disinfection systems. The work-environment culture should be carefully assessed and restructured using human engineering models to promote effective infection prevention practices. Antimicrobial stewardship initiatives are needed at the bedside and at national levels.

Norovirus Infection in Older Adults: Epidemiology, Risk Factors, and Opportunities for Prevention and Control

Norovirus is the leading cause of acute gastroenteritis. In older adults, it is responsible for an estimated 3.7 million illnesses; 320,000 outpatient visits; 69,000 emergency department visits; 39,000 hospitalizations; and 960 deaths annually in the United States. Older adults are particularly at risk for severe outcomes, including prolonged symptoms and death. Long-term care facilities and hospitals are the most common settings for norovirus outbreaks in developed countries. Diagnostic platforms are expanding. Several norovirus vaccines in clinical trials have the potential to reap benefits. This review summarizes current knowledge on norovirus infection in older adults.

Burden, duration and costs of hospital bed closures due to acute gastroenteritis in England per winter, 2010/11-2015/16

BACKGROUND

Bed closures due to acute gastroenteritis put hospitals under pressure each winter. In England, the National Health Service (NHS) has monitored the winter situation for all acute trusts since 2010/11.

AIM

To estimate the burden, duration and costs of hospital bed closures due to acute gastroenteritis in winter.

METHODS

A retrospective analysis of routinely collected time-series data of bed closures due to diarrhoea and vomiting was conducted for the winters 2010/11 to 2015/16. Two key issues were addressed by imputing non-randomly missing values at provider level, and filtering observations to a range of dates recorded in all six winters. The lowest and highest values imputed were taken to represent the best- and worst-case scenarios. Bed-days were costed using NHS reference costs, and potential staff absence costs were based on previous studies.

FINDINGS

In the best-to-worst case, a median of 88,000-113,000 beds were closed due to gastroenteritis each winter. Of these, 19.6-20.4% were unoccupied. On average, 80% of providers were affected, and had closed beds for a median of 15-21 days each winter. Hospital costs of closed beds were £5.7-£7.5 million, which increased to £6.9-£10.0 million when including staff absence costs due to illness.

CONCLUSIONS

The median number of hospital beds closed due to acute gastroenteritis per winter was equivalent to all general and acute hospital beds in England being unavailable for a median of 0.88-1.12 days. Costs for hospitals are high but vary with closures each winter.

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

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