Norovirus Outbreaks Research Articles

Modelling the effects of intervention measures in reducing the risk of norovirus transmission in preschool settings.

Singapore has seen an increase in norovirus outbreaks in preschools from 2019 to 2022 primarily due to person-to-person transmission. This study describes the use of compartmental susceptible-exposed-infectious-recovered (SEIR) modelling to simulate the spread of norovirus among preschool children in a classroom setting. Different intervention measures, such as isolation of infected preschoolers, handwashing and surface decontamination were modelled to quantify their effectiveness at reducing the number of children infected. We found that isolation of the sick child was the most effective single intervention to reduce transmission risk, which was 5 times more effective than handwashing. Coupled with handwashing and surface decontamination, transmission risk could be further reduced, close to zero. Findings from our study can be used to reiterate to parents and teachers on the importance of recognizing the symptoms exhibited by their unwell children and refraining from sending them to school, as this action poses a risk of transmitting norovirus to other children. In addition, our findings can be used to educate children and staff in preschools on the importance of practising good personal hygiene and regular environmental cleaning. Through this study, decision makers would be better informed on the effectivness of various risk mitigation measures at reduce the risk of norovirus transmission in preschool settings.

Municipal secondary-treated effluent data seem to be a suitable source of information for human viral trends

Employing a long-time series of municipal wastewater samples collected in 2020, the present study aims to confirm whether the appearance of SARS-CoV-2 influences the environmental load and behaviour of both JC Virus and Norovirus, determine the ability of the selected wastewater treatment plant (WWTP) to remove viral genomes, and assess if secondary-treated effluent data is somehow related to the incidence of the viral diseases reported by the local hospital. From the 11 raw influent and 52 secondary-treated effluent samples tested, JC Virus data present an occurrence frequency of 100 %, showing two different abundance patterns along the year, before and after the appearance of SARS-CoV-2. The constant detection of JC nucleic acids in wastewater reinforces the idea that urine is responsible for transmitting this virus. The Norovirus genogroup (G) II was detected more frequently than GI, both in influents and effluents, and their characteristic incidence peaks were not observed in late 2020. Regarding SARS-CoV-2 RNA, it appeared only in 5.8 % of the effluents, possibly due to the iron dosing used by the WWTP to reduce both phosphorus and organic matter concentrations in order to meet the requirements of European legislation, and/or the pre-filtration laboratory step which neglected the possibility of viral association with the solid fraction. The results suggest a poor performance of the WWTP, since Log removal values below 1.8 were determined. We were able to trace the development of local Norovirus outbreaks in the effluent samples to some extent, suggesting that secondary-treated effluents may be used to monitor human viruses by following viral nucleic acid levels.

Traceback and Testing of Food Epidemiologically Linked to a Norovirus Outbreak at a Wedding Reception

We investigated a suspected norovirus outbreak associated with a wedding reception in Wisconsin in May 2015. Fifty-six of 106 (53%) wedding attendees were interviewed, and 23 (41%) reported symptoms consistent with norovirus infection. A retrospective cohort study identified fruit salad as the likely vehicle of infection (risk ratio 3.2, 95% confidence interval 1.1–8.3). Norovirus was detected by real-time reverse transcription polymerase chain reaction (RT-qPCR) in stool specimens collected from four attendees and one food handler and in 12 leftover fruit salad samples from both an opened and a sealed container. Norovirus-positive clinical samples (n = 4) were genotyped as GII.4 Sydney and norovirus-positive fruit salad samples (n = 2) confirmed the presence of GII.4 norovirus by Sanger sequencing with 98% nucleotide (n = 236) similarity in 5′ end of ORF2 between fruit salad and clinical specimens. In conclusion, this comprehensive norovirus outbreak investigation combined epidemiologic, virologic, and environmental findings to traceback the contaminated food as the source of the outbreak.

Social Network Analysis of a Norovirus Outbreak at a Primary School - Zhuhai City, Guangdong Province, China, 2023.

The investigations and analyses limited to epidemiological characteristics are insufficient to analyze the spread patterns of norovirus outbreaks in schools. Norovirus outbreaks in primary schools are a dynamic process that spreads through social networks. The use of a social network analysis method to measure and identify key nodes for simulating control evolution was proven effective. Infected students exhibit priority connection characteristics at different developmental stages in the network topology. Identifying and deliberately targeting key nodes could destroy network connectivity and help reduce the spread of the outbreak.

A hybrid approach to study and forecast climate-sensitive norovirus infections in the USA

Norovirus, responsible for acute gastroenteritis and foodborne diseases in the United States, is influenced significantly by environmental factors. This study employs a hybrid approach to develop a foodborne disease model that incorporates indirect incidence to examine the correlation between norovirus outbreaks and environmental conditions, specifically focusing on the impact of temperature and humidity on virus transmission. By analyzing weekly average climate data and confirmed case data from four United States regions (Southern, Northeastern, Midwestern, and Western), we assess the mortality rates and estimate transmission rates using the inverse method. Our numerical results confirm that norovirus outbreaks predominantly occur in colder months. However, higher temperatures or increased humidity during warmer months appear to mitigate the spread of the virus. Utilizing climate data, this study also forecasts transmission rates and infection cases up to eight weeks in advance using a generalized boosting machine learning model.

Investigation of a Norovirus GII outbreak in a primary school in Portugal,2023

Abstract Background The onset of acute gastroenteritis cases among students in a primary school class on September 19, 2023, prompted an immediate response from the local Public Health unit. A collaborative effort was initiated to investigate and contain the outbreak. Methods Epidemiological questionnaires were distributed to 166 students and 8 staff members, defining cases as individuals exhibiting symptoms including diarrhoea, vomiting, or nausea between September 19th and September 24th, 2023. Additionally, stool samples were collected from three individuals. Results Out of 166 students and 8 staff members, 39 individuals met the case definition, resulting in attack rates of 22% (37/166) and 25% (2/8) among students and staff, respectively. Laboratory analysis confirmed two cases of Norovirus GII among the tested specimens, with five students requiring medical attention. Conclusions Our investigation underscores the significance of continuous epidemiological surveillance and swift implementation of infection control measures in school settings. The detection of Norovirus transmission emphasizes the necessity for rigorous adherence to infection control best practices. Our findings advocate for sustained technical support from public health authorities to prevent and manage similar outbreaks effectively. Key messages • Study on Norovirus outbreak in a primary school highlights the imperative of infection control measures, emphasizing the importance of ongoing support from public health authorities. • The Norovirus outbreak investigation underscores the vital role of surveillance and swift response in containing infectious diseases within educational settings safeguarding all.

Investigation of a Norovirus GII.4Sydney[P16] outbreak in a care facility in Portugal, 2022

Abstract Background On the 29th of April 2022 the local Public Health unit was notified of 12 cases of acute gastroenteritis in residents of a long-term care facility (LTCF). A joint epidemiological investigation team was established and initiated an outbreak investigation to characterize the outbreak and implement infection control measures. Methods Epidemiological questionnaires were administered to staff (n = 44) and residents (n = 60). Case definition was LTCF residents or staff members with at least one of the following symptoms: diarrhoea, vomiting, nausea, between April 25th and May 14th, 2022. Stool or vomit samples were collected for 11 individuals. To assess environmental contamination fifteen food samples from previous meals and six surface samples from toilet faucets, wash tubs, and cutting boards were collected. Spatial distribution of cases within the LTCF was performed to guide infection control implementation. Results A total of 43 people met the case definition. Attack rates in residents and staff were 37% (23/63) and 42% (20/48), respectively. Of the total tested specimens, six (6/8) from residents and two (2/3) from staff were positive for the Norovirus (NoV) GII.4 Sydney [P16] variant by genotyping. Two (2/6) samples from surface swabs from the toilet faucet in the resident’s living room were also positive for NoV GII. Food samples were negative for major bacterial agents implicated in gastrointestinal outbreaks. Cases were distributed throughout the LTCF wards with no clear clustering. Four residents required hospital admission. Conclusions Results suggest person-to-person as well as environmental transmission of NoV. Identification of behavioural and spatial patterns of residents and staff and subsequent enactment of infection control strategies mitigated the outbreak. These findings reinforce the need for public health to maintain continuous technical support to LTCF on the implementation of infection control best practices. Key messages • Outbreak investigation in LTCF confirms Norovirus transmission, emphasizing the importance of infection control measures in long-term care facilities. • Study reveals Norovirus outbreak in LTCF, underscores the role of person-to-person and environmental transmission, highlighting the need for robust infection control protocols.

Norovirus outbreaks due to contaminated drinking water and probable person-to-person transmission, Kerala, India, 2021

BackgroundIn July 2021, the Alappuzha district in Kerala, India, reported an unexpected number of acute gastroenteritis (772) cases (Outbreak A). On October 10, 2021, a university in Wayanad, Kerala, reported 25 acute gastroenteritis cases (Outbreak B). We described both the outbreaks and determined the agent, source and risk factors. MethodsWe defined a suspected case as the occurrence of vomiting or at least three episodes of loose stools within 24 h and a confirmed case as those with stool samples/rectal swabs positive for norovirus. We did a matched case-control study in Outbreak A and a retrospective cohort study in Outbreak B. We calculated the adjusted odds ratio (aOR) in outbreak A, relative risk (aRR) in outbreak B and population attributable fraction (PAF). We tested stool and water samples for bacteria and viruses. ResultsWe identified Group II norovirus in stool samples in both outbreaks and 4/5 water samples in Outbreak A. Suspected norovirus infection was associated with drinking inadequately boiled water from the municipal water supply in outbreak A [aOR: 4.5; 95 % C.I: 1.2–15.8; PAF: 0.23] and well water in hostels in outbreak B [aRR: 2.2; 95 % C.I: 1.2–3.9; PAF: 0.15]. In Outbreak A, groundwater from tube wells was mixed in the municipal water supply overhead tanks without chlorination. ConclusionThe gastroenteritis outbreaks were caused by Group II norovirus due to the consumption of inadequately boiled contaminated groundwater (outbreak A) and well water (outbreak B). We recommended superchlorination of overhead tanks and wells and boiled water for drinking.

Molecular Characterization of Noroviruses Causing Acute Gastroenteritis Outbreaks among US Military Recruits, 2013-2023.

Norovirus is the leading cause of acute gastroenteritis (AGE) worldwide. Norovirus outbreaks at military facilities can cause loss of training and working days and increased healthcare utilization, affecting force readiness. During 2013-2023, we enrolled 2,304 US military recruits from 4 basic training facilities to investigate AGE outbreaks among this population. Among enrollees, we detected norovirus in 433 (18.8%) AGE cases, and norovirus caused 49 AGE outbreaks during our longitudinal study. On average, each norovirus case-patient missed 1.2 training days due to illness, and 6.2% required infusion care. Whole-genome sequencing of selected samples from each outbreak produced full-length genomes (6,989-7,787 bp) for 39 samples. Norovirus GII.4 Sydney was the most (12/39, 30.8%) identified genotype over the study period. Phylogenetic and comparative genomic analyses revealed that several outbreak strains were responsible for causing >1 outbreak, even across different training sites. Our findings can inform infection control practices at military installations and overall norovirus vaccine development.

Increased circulation of GII.17 noroviruses, six European countries and the United States, 2023 to 2024.

We report an increase in GII.17 norovirus outbreaks and sporadic infections of acute gastroenteritis in Austria, Germany, France, Ireland, the Netherlands, England and the United States during the 2023/24 season. A decrease in GII.4 coincided with GII.17 prevalence increasing to between 17% and 64% of all GII detections. Overall, 84% of the GII.17 strains clustered closely with strains first reported in Romania in 2021 and two new sub-lineages were identified. Norovirus surveillance and molecular characterisation should be prioritised this winter.

Sacred journeys and pilgrimages: health risks associated with travels for religious purposes.

Pilgrimages and travel to religious Mass Gatherings (MGs) are part of all major religions. This narrative review aims to describe some characteristics, including health risks, of the more well known and frequently undertaken ones. A literature search was conducted using keywords related to the characteristics (frequency of occurrence, duration, calendar period, reasons behind their undertaking and the common health risks) of Christian, Muslim, Hindu, Buddhist and Jewish religious MGs. About 600 million trips are undertaken to religious sites annually. The characteristics varies between religions and between pilgrimages. However, religious MGs share common health risks, but these are reported in a heterogenous manner. European Christian pilgrimages reported both communicable diseases, such as norovirus outbreaks linked to the Marian Shrine of Lourdes in France, and noncommunicable diseases (NCD). NCD predominated at the Catholic pilgrimage to the Basilica of Our Lady of Guadalupe in Mexico, which documented 11 million attendees in one week. The Zion Christian Church Easter gathering in South Africa, attended by about 10 million pilgrims, reported mostly motor vehicles accidents. Muslim pilgrimages, such as the Arbaeen (20 million pilgrims) and Hajj documented a high incidence of respiratory tract infections, up to 80% during Hajj. Heat injuries and stampedes have been associated with Hajj. The Hindu Kumbh Mela pilgrimage, which attracted 100 million pilgrims in 2013, documented respiratory conditions in 70% of consultations. A deadly stampede occurred at the 2021 Jewish Lag BaOmer MG. Communicable and NCD differ among the different religious MGs. Gaps exists in the surveillance, reporting, and data accessibility of health risks associated with religious MGs. A need exists for the uniform implementation of a system of real-time monitoring of diseases and morbidity patterns, utilising standardised modern information-sharing platforms. The health needs of pilgrims can then be prioritised by developing specific and appropriate guidelines.

Risk Factors for Norovirus Outbreaks in Schools and Kindergartens - Beijing Municipality, China, July 2017-June 2022.

Norovirus is the leading cause of global acute gastroenteritis outbreaks. Norovirus outbreaks mainly occur in schools and kindergartens in China, always causing public health issues. Conditional logistic regression method was used to analyze the risk factors for norovirus outbreaks in schools and kindergartens, and found that students vomiting at school or kindergarten, case activity in public areas, and the first case's classroom less than 5 meters from toilets were risk factors. Effective measures to address these factors can help reduce the risk of norovirus outbreaks in schools and kindergartens.

Changes in norovirus incidence in Victoria, Australia, 2022: are we back to normal yet after COVID?

There were 108 norovirus-positive outbreaks in 2022, with 45 (41.7%) occurring during the first quarter (Q1), January-March. Aged care facilities accounted for 44.4% of norovirus-positive outbreaks; 43.5% were in childcare settings. Overall, the GII.P31/GII.4 genotype was the most common, involved in 39.4% of outbreaks; however, there were shifts in the most common genotype across the year. In Q1, the GII.P31/GII.4 genotype accounted for 73.3% of typed outbreaks, but by Q3 (July-September) the GII.P7/GII.6 was the most prominent genotype at 45.0%. In Q4 (October-December), the dominant genotype had changed again to GII.P16/GII.4 (52.6%). While the incidence of norovirus outbreaks in 2022 was average regarding overall prevalence and genotype diversity, there are still ongoing effects from the coronavirus disease 2019 (COVID-19) pandemic in relation to seasonality, outbreak demographics and specimen referral.

Development of a broad-spectrum therapeutic Fc-nanobody for human noroviruses.

Human norovirus was discovered more than five decades ago and is a widespread cause of outbreaks of acute gastroenteritis. There are no approved vaccines or antivirals currently available. However, norovirus inhibitors, including capsid-specific monoclonal antibodies (Mabs) and nanobodies, have recently shown promising results. Several Mabs and nanobodies were found to inhibit norovirus replication using a human intestinal enteroid (HIE) culture system and/or could block norovirus attachment to histo-blood group antigen (HBGA) co-factors. In our pursuit to develop a single broad-spectrum norovirus therapeutic, we continued our analysis and development of a cross-reactive and HBGA interfering nanobody (NB26). To improve NB26 binding capacity and therapeutic potential, we conjugated NB26 onto a human IgG Fc domain (Fc-NB26). We confirmed that Fc-NB26 cross-reacts with genetically diverse GII genotype capsid protruding (P) domains (GII.8, GII.14, GII.17, GII.24, GII.26, and GII.NA1) using a direct enzyme-linked immunosorbent assay. Furthermore, X-ray crystallography structures of these P domains and structures of other GII genotypes reveal that the NB26 binding site is largely conserved, validating its broad reactivity. We showed that Fc-NB26 has ~100-fold higher affinity toward the norovirus P domain compared to native NB26. We also found that both NB26 and Fc-NB26 neutralize human norovirus replication in the HIE culture system. Furthermore, the mode of inhibition confirmed that like NB26, Fc-NB26 caused norovirus particle disassembly and aggregation. Overall, these new findings demonstrate that structural modifications to nanobodies can improve their therapeutic potential.IMPORTANCEDeveloping vaccines and antivirals against norovirus remains a challenge, mainly due to the constant genetic and antigenic evolution. Moreover, re-infection with genetically related and/or antigenic variants is not uncommon. We further developed our leading norovirus nanobody (NB26) that indirectly interfered with norovirus binding to HBGAs, by converting NB26 into a dimeric Fc-linked Nanobody (Fc-NB26). We found that Fc-NB26 had improved binding affinity and neutralization capacity compared with native NB26. Using X-ray crystallography, we showed this nanobody engaged highly conserved capsid residues among genetically diverse noroviruses. Development of such broadly reactive potent therapeutic nanobodies delivered as a slow-releasing prophylactic could be of exceptional value for norovirus outbreaks, especially for the prevention or treatment of severe acute gastroenteritis in high-risk groups such as the young, elderly, and immunocompromised.

Measures for preventing norovirus outbreaks on campus in economically underdeveloped areas and countries: evidence from rural areas in Western China.

The outbreak of norovirus represents a significant public health emergency within densely populated, impoverished, and underdeveloped areas and countries. Our objective is to conduct an epidemiology study of a norovirus outbreak that occurred in a kindergarten located in rural western China. We aim to raise awareness and garner increased attention towards the prevention and control of norovirus, particularly in economically underdeveloped regions. Retrospective on-site epidemiological investigation results, including data on school layout, case symptoms, onset time, disposal methods and sample testing results, questionnaire surveys, and case-control study were conducted in a kindergarten to analyze the underlying causes of the norovirus outbreak. A total of 15 cases were identified, with an attack rate of 44.12% (15/34). Among them, 10 cases were diagnosed through laboratory tests, and 5 cases were diagnosed clinically. Vomiting (100%, 15/15) and diarrhea (93.33%, 14/15) were the most common symptoms in the outbreak. Case control study revealed that cases who had close contact (<1 m) with the patient's vomitus (OR = 5.500) and those who had close contact with similar patients (OR = 8.000) had significantly higher ORs compared to the control participants. The current study demonstrated that improper handling of vomitus is positively associated with norovirus outbreak. The absence of standardized disinfection protocols heightens the risk of norovirus outbreaks. To our knowledge, this study represents the first investigation into a norovirus outbreak in rural areas of western China. We aspire that amidst rapid economic development, a greater emphasis will be placed on the prevention and control of infectious diseases in economically underdeveloped areas and countries.

QAPI 113 - A Comprehensive infection control response to a norovirus outbreak on an adult inpatient hematologic oncology and clinical trials unit

QAPI 113 - A Comprehensive infection control response to a norovirus outbreak on an adult inpatient hematologic oncology and clinical trials unit

Identifying SNP threshold from P2 sequences for investigating norovirus transmission

Noroviruses are a group of non-enveloped single-stranded positive-sense RNA virus belonging to Caliciviridae family. They can be transmitted by the fecal-oral route from contaminated food and water and cause mainly acute gastroenteritis. Outbreaks of norovirus infections could be difficult to detect and investigate. In this study, we developed a simple threshold detection approach based on variations of the P2 domain of the capsid protein. We obtained sequences from the norovirus hypervariable P2 region using Sanger sequencing, including 582 pairs of epidemiologically-related strains from 35 norovirus outbreaks and 6402 pairs of epidemiologically-unrelated strains during the four epidemic seasons. Genetic distances were calculated and a threshold was performed by adopting ROC (Receiver Operating Characteristic) curve which identified transmission clusters in all tested outbreaks with 80 % sensitivity. In average, nucleotide diversity between outbreaks was 67.5 times greater than the diversity within outbreaks. Simple and accurate thresholds for detecting norovirus transmissions of three genotypes obtained here streamlines molecular investigation of norovirus outbreaks, thus enabling rapid and efficient responses for the control of norovirus.

Tracking diarrhea viruses and mpox virus using the wastewater surveillance network in Hong Kong

The wastewater surveillance network successfully established for COVID-19 showed great potential to monitor other infectious viruses, such as norovirus, rotavirus and mpox virus. In this study, we established and validated detection methods for these viruses in wastewater. We developed a supernatant-based method to detect RNA viruses from wastewater samples and applied it to the monthly diarrhea viruses (norovirus genogroup I & II, and rotavirus) surveillance in wastewater treatment plants (WWTPs) at a city-wide level for 16 months. Significant correlations were observed between the diarrhea viruses concentrations in wastewater and detection rates in faecal specimens by clinical surveillance. The highest norovirus concentration in wastewater was obtained in winter, consistent with the seasonal pattern of norovirus outbreak in Hong Kong. Additionally, we established a pellet-based method to monitor DNA viruses in wastewater and detected weak signals for mpox virus in wastewater from a WWTP serving approximately 16,700 people, when the first mpox patient in Hong Kong was admitted to the hospital within the catchment area. Genomic sequencing provided confirmatory evidence for the validity of the results. Our findings emphasized the efficacy of the wastewater surveillance network in WWTPs as a cost-effective tool to track the transmission trend of diarrhea viruses and to provide sensitive detection of novel emerging viruses such as mpox virus in low-prevalence areas. The developed methods and surveillance results provide confidence for establishing robust wastewater surveillance programs to control infectious diseases in the post-pandemic era.

Development and Evaluation of a Rapid GII Norovirus Detection Method Based on CRISPR-Cas12a.

Norovirus is highly infectious and rapidly transmissible and represents a major pathogen of sporadic cases and outbreaks of acute gastroenteritis worldwide, causing a substantial disease burden. Recent years have witnessed a dramatic increase in norovirus outbreaks in China, significantly higher than in previous years, among which GII norovirus is the predominant prevalent strain. Therefore, rapid norovirus diagnosis is critical for clinical treatment and transmission control. Hence, we developed a molecular assay based on RPA combined with the CRISPER-CAS12a technique targeting the conserved region of the GII norovirus genome, the results of which could be displayed by fluorescence curves and immunochromatographic lateral-flow test strips. The reaction only required approximately 50 min, and the results were visible by the naked eye with a sensitivity reaching 102 copies/μl. Also, our method does not cross-react with other common pathogens that cause intestinal diarrhea. Furthermore, this assay was easy to perform and inexpensive, which could be widely applied for detecting norovirus in settings including medical institutions at all levels, particularly township health centers in low-resource areas.

Socioeconomic impacts of airborne and droplet-borne infectious diseases on industries: a systematic review

BackgroundRecent pandemics have had far-reaching effects on the world’s largest economies and amplified the need to estimate the full extent and range of socioeconomic impacts of infectious diseases outbreaks on multi-sectoral industries. This systematic review aims to evaluate the socioeconomic impacts of airborne and droplet-borne infectious diseases outbreaks on industries.MethodsA structured, systematic review was performed according to the PRISMA guidelines. Databases of PubMed, Scopus, Web of Science, IDEAS/REPEC, OSHLINE, HSELINE, and NIOSHTIC-2 were reviewed. Study quality appraisal was performed using the Table of Evidence Levels from Cincinnati Children’s Hospital Medical Center, Joanna Briggs Institute tools, Mixed Methods Appraisal Tool, and Center of Evidence Based Management case study critical appraisal checklist. Quantitative analysis was not attempted due to the heterogeneity of included studies. A qualitative synthesis of primary studies examining socioeconomic impact of airborne and droplet-borne infectious diseases outbreaks in any industry was performed and a framework based on empirical findings was conceptualized.ResultsA total of 55 studies conducted from 1984 to 2021 were included, reporting on 46,813,038 participants working in multiple industries across the globe. The quality of articles were good. On the whole, direct socioeconomic impacts of Coronavirus Disease 2019, influenza, influenza A (H1N1), Severe Acute Respiratory Syndrome, tuberculosis and norovirus outbreaks include increased morbidity, mortality, and health costs. This had then led to indirect impacts including social impacts such as employment crises and reduced workforce size as well as economic impacts such as demand shock, supply chain disruptions, increased supply and production cost, service and business disruptions, and financial and Gross Domestic Product loss, attributable to productivity losses from illnesses as well as national policy responses to contain the diseases.ConclusionsEvidence suggests that airborne and droplet-borne infectious diseases have inflicted severe socioeconomic costs on regional and global industries. Further research is needed to better understand their long-term socioeconomic impacts to support improved industry preparedness and response capacity for outbreaks. Public and private stakeholders at local, national, and international levels must join forces to ensure informed systems and sector-specific cost-sharing strategies for optimal global health and economic security.