Norovirus gastroenteritis

The role of gastrointestinal pathogen PCR testing in liver transplant recipients hospitalized with diarrhea

BACKGROUND

Diarrhea is a common symptom among liver transplant (LT) recipients and can result in significant morbidity. The utility of PCR-based multiplex gastrointestinal (GI) pathogen panels in this population is unknown.

METHODS

We assessed incidence, predictors, and outcomes of GI PCR positivity among inpatients who underwent stool pathogen testing with the FilmArray multiplex GI PCR panel at our institution within 1 year following LT from April 2015 to December 2019.

RESULTS

112 patients were identified. 14 (12.5%) had a positive PCR for any pathogen. Escherichia coli (n = 9) and Norovirus (n = 5) were the most common pathogens detected. Recipients with a positive PCR were significantly further from LT (median 74.5 vs 15.5 days, p < 0.01) and tested earlier during hospitalization (median 1.0 vs 9.0 days, p < 0.01). C. difficile was positive in 20.0% of patients with a positive PCR and 11.4% with a negative PCR. CMV viremia was observed in 11.6% of patients, all in the negative PCR group. Following a positive PCR, patients were more likely to have a change in antimicrobial regimen (71.4% vs 28.6%, p = 0.02), a shorter length of stay (median 7.5 vs. 17.5 days, p < 0.01), and a trend toward lower rates of readmission and colonoscopy within 30 days.

CONCLUSIONS

In hospitalized LT recipients with diarrhea, GI PCR pathogen identification was associated with the use of targeted antimicrobial therapy and a shorter length of stay. GI PCR testing should be considered early during admission and later in the post-LT period. This article is protected by copyright. All rights reserved.

Embracing the heterogeneity of natural viruses in mouse studies

Animal models are a critical tool in modern biology. To increase reproducibility and to reduce confounding variables modern animal models exclude many microbes, including key natural commensals and pathogens. Here we discuss recent strategies to incorporate a natural microbiota to laboratory mouse models and the impacts the microbiota has on immune responses, with a focus on viruses.

Immunity to enteric viruses

Pathogenic enteric viruses are a major cause of morbidity and mortality, particularly among children in developing countries. The host response to enteric viruses occurs primarily within the mucosa, where the intestinal immune system must balance protection against pathogens with tissue protection and tolerance to harmless commensal bacteria and food. Here, we summarize current knowledge in natural immunity to enteric viruses, highlighting specialized features of the intestinal immune system. We further discuss how knowledge of intestinal anti-viral mechanisms can be translated into vaccine development with particular focus on immunization in the oral route. Research reveals that the intestine is a complex interface between enteric viruses and the host where environmental factors influence susceptibility and immunity to infection, while viral infections can have lasting implications for host health. A deeper mechanistic understanding of enteric anti-viral immunity with this broader context can ultimately lead to better vaccines for existing and emerging viruses.

Human Norovirus Induces Aquaporin 1 Production by Activating NF-κB Signaling Pathway

Human norovirus (HuNoV) is one of the major pathogens of acute nonbacterial gastroenteritis. Due to the lack of a robust and reproducible in vitro culture system and an appropriate animal model, the mechanism underlying HuNoV-caused diarrhea remains unknown. In the current study, we found that HuNoV transfection induced the expression of aquaporin 1 (AQP1), which was further confirmed in the context of virus infection, whereas the enterovirus EV71 (enterovirus 71) did not have such an effect. We further revealed that VP1, the major capsid protein of HuNoV, was crucial in promoting AQP1 expression. Mechanistically, HuNoV induces AQP1 production through the NF-κB signaling pathway via inducing the expression, phosphorylation and nuclear translocation of p65. By using a model of human intestinal epithelial barrier (IEB), we demonstrated that HuNoV and VP1-mediated enhancement of small molecule permeability is associated with the AQP1 channel. Collectively, we revealed that HuNoV induced the production of AQP1 by activating the NF-κB signaling pathway. The findings in this study provide a basis for further understanding the significance of HuNoV-induced AQP1 expression and the potential mechanism underlying HuNoV-caused diarrhea.

Multiplex detection of eight different viral enteropathogens in clinical samples, combining RT-PCR technology with melting curve analysis

Background

Early and accurate identification of infection viruses among children can benefit the personalized medical treatment and management, and reduce the future occurrence of serious symptoms. Thus, it is critical to develop a high-throughput multiplex real-time RT-PCR method to improve the accuracy and efficiency in routine clinical lab tests.

Methods

We developed a real time RT-PCR combined with melting curve analysis (RRCMC) method for simultaneous detection of rotavirus A, B, C, norovirus GI and GII, adenovirus, astrovirus and sapovirus.

Results

Stool samples were collected from 160 children with acute diarrhea and tested by RRCMC assay. A total of 71 patients were tested positive with norovirus, adenovirus or rotavirus. The RRCMC assay has high specificity. There is no internal cross-reaction among the 8 diarrhea viruses and no cross-reaction of other commonly intestinal pathogens and human genome. The limit detection was ranged from 1 × 10² to 1 × 10⁵ nucleic acid copies/ml for each diarrhea virus.

Conclusion

The RRCMC method is a suitable rapid clinical test for infectious viruses, with the advantages of high-throughput, low cost, high sensitivity and specificity.

Risk Factors for Norovirus Infections and Their Association with Childhood Growth: Findings from a Multi-Country Birth Cohort Study

The prevalence of norovirus infections in different geographical locations and their attribution to childhood diarrhea is well established. However, there are no reports showing possible relationships of different norovirus genogroups with subsequent childhood malnutrition. In this study, we attempted to establish a potential association between asymptomatic norovirus infections with childhood growth faltering during. Non-diarrheal stools were collected from 1715 children enrolled in locations in a multi-county birth cohort study across eight different geographical locations and were assessed for norovirus genogroup I (GI) and norovirus genogroup II (GII). Asymptomatic norovirus GI infections were negatively associated with monthly length-for-age Z score/LAZ (β = -0.53, 95% CI: -0.73, -0.50) and weight-for-age Z score/WAZ (β = -0.39, 95% CI: -0.49, -0.28), respectively. The burden of asymptomatic norovirus GI infections was negatively associated with LAZ (β = -0.46, 95% CI: -0.67, -0.41) and WAZ (β = -0.66, 95% CI: -0.86, -0.53) at 2 years of age, whilst the burden of asymptomatic norovirus GII infections was negatively associated with WAZ (β = -0.27, 95% CI: -0.45, -0.25) at 2 years of age. Our findings warrant acceleration in attempts to develop vaccines against norovirus GI and norovirus GII, with the aim of minimizing the long-term sequelae on childhood growth.

Molecular epidemiological characteristics of the virus in 96 children with acute diarrhea in Changdu of Tibet, China

OBJECTIVES

To study the molecular epidemiological characteristics of the virus in children with acute viral diarrhea in Changdu of Tibet, China.

METHODS

Fecal specimens were collected from 96 children with acute diarrhea who visited the People's Hospital of Changdu, Tibet, from November 2018 to November 2020 and were tested for adenovirus, norovirus, astrovirus, sapovirus, and rotavirus. Gene sequencing was performed for the genotypes of these viruses.

RESULTS

The overall positive rate of the five viruses was 39% (37/96), among which astrovirus had the highest positive rate of 17%, followed by norovirus (9%), rotavirus (8%), adenovirus (7%), and sapovirus (5%). There was no significant difference in the positive rate of the five viruses among different age groups (P>0.05). Only the positive rate of astrovirus was significantly different among the four seasons (P<0.05). For adenovirus, 6 children had F41 type and 1 had C2 type; for norovirus, 6 had GⅠ.3 type, 1 had GⅠ.7 type, 1 had GⅡ.3 type, and 2 had GⅡ.4 Sydney_2012 type; HAstrV-1 type was observed in all children with astrovirus infection; for sapovirus, 1 child each had sporadic GⅠ.2, GⅠ.6, and GⅡ.1 sapovirus and 2 children had unknown type; 6 children had rotavirus G9[P8].

CONCLUSIONS

Astrovirus and norovirus are important pathogens in children with acute diarrhea in Changdu, Tibet. The positive rate of adenovirus, norovirus, astrovirus, sapovirus, and rotavirus is not associated with age, and only the positive rate of astrovirus has obvious seasonality. F41 type is the dominant genotype of adenovirus; GⅠ.3 is the dominant genotype of norovirus; HAstrV-1 is the dominant genotype of astrovirus; sporadic GⅠ.2, GⅠ.6, and GⅡ.1 are the dominant genotypes of sapovirus; G9[P8] is the dominant genotype of rotavirus.

Surveillance of Adenovirus and Norovirus Contaminants in the Water and Shellfish of Major Oyster Breeding Farms and Fishing Ports in Taiwan

The enteric viruses, including adenovirus (AdVs) and norovirus (NoVs), in shellfish is a significant food safety risk. This study investigated the prevalence, seasonal occurrence, genetic diversity, and quantification of AdVs and NoVs in the water and cultured shellfish samples at the four major coastal oyster breeding farms (COBF), five major fishing ports (FP), and their markets in Taiwan. The AdVs/NoVs in the water and shellfish samples were isolated by the membrane filtration and direct elution methods. The RNA of NoVs was reverse-transcribed into complementary DNA through reverse transcription reaction. Further NoVs and AdVs were detected using nested PCR. A higher detection rate was recorded in the low-temperature period than high-temperature. Detection difference was noted between nested PCR and qPCR outcomes for AdVs. The total detection rate of AdVs was higher in the water samples (COBF-40.6%, FP 20%) than the shellfish samples (COBF-11.7% and FP 6.3%). The AdVs load in the water and shellfish samples ranged from 1.23 × 103 to 1.00 × 106 copies/L and 3.57 × 103 to 4.27 × 104 copies/100g, respectively. The total detection of NoVs was highest in the water samples of the FP and their market shellfish samples (11.1% and 3.2%, respectively). Genotyping and phylogenetic analysis were identified as the prevalent AdVs and NoVs genotypes in the water and shellfish samples: A species HAdVs serotype 12; F species HAdVs serotype 41; and C species PAdVs serotype 5 (NoVs GI.2, GI.3 and GII.2). No significant differences were observed between the presence of AdVs, and all of the water quality parameters evaluated (heterotrophic plate count, water temperature, turbidity, pH, salinity, and dissolved oxygen). The virus contamination occurs mainly due to the direct discharge of domestic sewage, livestock farm, and fishing market wastewater into the coastal environment. Thus, this study suggested framing better estuarine management to prevent AdVs/NoVs transmission in water and cultured/distributed shellfish.

Recent Developments in Isothermal Amplification Methods for the Detection of Foodborne Viruses

Foodborne and enteric viruses continue to impose a significant public health and economic burden globally. As many of these viruses are highly transmissible, the ability to detect them portably, sensitively, and rapidly is critical to reduce their spread. Although still considered a gold standard for detection of these viruses, real time polymerase chain reaction (PCR)-based technologies have limitations such as limited portability, need for extensive sample processing/extraction, and long time to result. In particular, the limitations related to the susceptibility of real time PCR methods to potential inhibitory substances present in food and environmental samples is a continuing challenge, as the need for extensive nucleic acid purification prior to their use compromises the portability and rapidity of such methods. Isothermal amplification methods have been the subject of much investigation for these viruses, as these techniques have been found to be comparable to or better than established PCR-based methods in portability, sensitivity, specificity, rapidity, and simplicity of sample processing. The purpose of this review is to survey and compare reports of these isothermal amplification methods developed for foodborne and enteric viruses, with a special focus on the performance of these methods in the presence of complex matrices.

Bacterial travellers' diarrhoea: A narrative review of literature published over the past 10 years

Travellers' diarrhoea (TD) is the most frequent illness experienced by international travellers to lower-income countries with bacterial agents considered to account for 80-90% of cases. In this review, we summarise evidence published on bacterial TD over the past 10 years, focusing on the epidemiology and aetiology of TD. Diarrhoeagenic Escherichia coli (DEC) continue to be the most commonly implicated bacteria in TD, although Enteropathogenic E. coli (EPEC) and Enteroaggregative E. coli (EAEC) now appear to be predominant where Enterotoxigenic E. coli (ETEC) was previously considered most prevalent globally. Where fluroquinolone resistance had primarily been documented for Campylobacter in Southeast Asia, widespread resistance has been observed in most regions of the world for multiple enteropathogens, including Shigella, Salmonella, ETEC and EAEC. Implementation of novel molecular methods for pathogen detection has led to identification of bacterial pathogens, including Clostridium difficile (with and without the use of prior antibiotics), Arcobacter species and Bacteroides fragilis, as aetiological agents in TD. The widespread resistance to first-line antibiotics in multiple bacterial enteropathogens warrants continued surveillance and re-evaluation of current treatment practices. Further investigations are required to determine the prevalence and geographical distribution of bacterial enteropathogens that have been more recently implicated in TD.

Epidemiological and Genetic Characterization of Norovirus Outbreaks That Occurred in Catalonia, Spain, 2017–2019

Molecular characterization of human norovirus (HuNoV) genotypes enhances the understanding of viral features and illustrates distinctive evolutionary patterns. The aim of our study was to describe the prevalence of the genetic diversity and the epidemiology of the genotypes involved in HuNoV outbreaks in Catalonia (Spain) between 2017 and 2019. A total of 100 HuNoV outbreaks were notified with the predominance of GII (70%), followed by GI (27%) and mixed GI/GII (3%). Seasonality was observed for GII outbreaks only. The most prevalent genotypes identified were GII.4[P31] Sydney 2012, GII.4[P16] Sydney 2012 and GII.2[P16]. As compared to person-to-person (P/P) transmitted outbreaks, foodborne outbreaks showed significantly higher attack rates and lower duration. The average attack rate was higher in youth hostel/campgrounds compared to nursing homes. Only genotypes GI.4[P4], GII.2[P16], GII.4[P16], GII.4[P31] and GII.17[P17] were consistently detected every year, and only abundance of GII.2[P16] showed a negative trend over time. GII.4 Sydney 2012 outbreaks were significantly associated to nursing homes, while GII.2[P16] and GI.3[P3] were most frequently identified in youth hostel/campgrounds. The average attack rate was significantly higher when comparing GII.2[P16] vs. GI.4[P4], GII.2[P16] vs. GII.4[P31] Sydney 2012, and GII.6[P7] vs. GII.4[P31] Sydney 2012. No correlations were found between genotype and outbreak duration or age of affected individuals.

Safety and immunogenicity studies in animal models support clinical development of a bivalent norovirus-like particle vaccine produced in plants

Noroviruses (NoV) are the leading cause of epidemic acute gastroenteritis in humans worldwide. A safe and effective vaccine that prevents NoV infection or minimizes NoV disease burden is needed, especially for children and the elderly who are particularly susceptible to NoV disease. A plant-based expression system (magnICON®) was used to manufacture two different virus-like particle (VLP) immunogens derived from human NoV genogroups I and II, genotype 4 (GI.4 and GII.4), which were subsequently blended 1:1 (w/w) into a bivalent vaccine composition (rNV-2v). Here, we report on the safety and immunogenicity of rNV-2v from one pilot and two GLP-compliant toxicity studies in New Zealand White rabbits administered the vaccine subcutaneously (SC) or intramuscularly (IM). Strong genogroup-specific immune responses were induced by vaccination without adjuvant at various doses (200 to 400 μg VLP/administration) and administration schedules (Days 1 and 7; or Days 1, 15 and 29). The results showed sporadic local irritation at the injection site, which resolved over time, and was non-adverse and consistent with expected reactogenicity. There were no signs of systemic toxicity related to vaccine administration relative to vehicle-treated controls with respect to clinical chemistry, haematology, organ weights, macroscopic examinations, or histopathology. In a 3-administration regimen (n + 1 the clinical regimen), the NOAEL for rNV-2v via the SC or IM route was initially determined to be 200 μg. An improved GI.4 VLP variant mixed 1:1 (w/w) with the wild-type GII.4 VLP was subsequently evaluated via the IM route at a higher dose in the same 3-administration model, and the NOAEL was raised to 300 µg. Serology performed in samples of both toxicity studies showed significant and substantial anti-VLP-specific antibody titers for rNV-2v vaccines administered via the IM or SC route, as well as relevant NoV blocking antibody responses. These results support initiation of clinical development of the plant-made NoV vaccine.

Long-Term Infectious Complications of Kidney Transplantation

Infections remain a common complication of solid-organ transplantation. Most infections in the first month after transplant are typically health care-associated infections, whereas late infections, beyond 6-12 months, are community-acquired infections. Opportunistic infections most frequently present in the first 12 months post-transplant and can be modulated on prior exposures and use of prophylaxis. In this review, we summarize the current epidemiology of postkidney transplant infections with a focus on key viral (BK polyomavirus, cytomegalovirus, Epstein-Barr virus, and norovirus), bacterial (urinary tract infections and Clostridioides difficile colitis), and fungal infections. Current guidelines for safe living post-transplant are also summarized. Literature supporting prophylaxis and vaccination is also provided.

The Rise in Norovirus-Related Acute Gastroenteritis During the Fight Against the COVID-19 Pandemic in Southern China

Background: There has been a significant decline in the morbidity of almost all infectious diseases during the COVID-19 pandemic. However, while the incidence of norovirus-related acute gastroenteritis declined in Guangzhou, China during the initial period of the pandemic, incidence increased significantly once the new school year began in September 2020.

Methods: Norovirus-related acute gastroenteritis clusters and outbreaks were assessed in Guangzhou from 2015 to 2020. Medians and interquartile ranges were compared between groups using the Mann–Whitney U-test, and attack rates were calculated.

Results: While 78,579 cases of infectious diarrhea were reported from 2015 to 2019, with an average of 15,716 cases per year, only 12,065 cases of infectious diarrhea were reported in 2020. The numbers of sporadic cases and outbreaks reported from January to August 2020 were lower than the average numbers reported during the same time period each year from 2015 to 2019 but began to increase in September 2020. The number of cases in each reported cluster ranged from 10 to 70 in 2020, with a total of 1,280 cases and an average attack rate of 5.85%. The median number of reported cases, the cumulative number of cases, and the attack rate were higher than the average number reported each year from 2015 to 2019. The intervention time in 2020 was also higher than the average intervention time reported during 2015–2019. The main norovirus genotypes circulating in Guangzhou during 2015–2020 included genogroup 2 type 2 (GII.2) (n = 79, 26.69%), GII.17 (n = 36, 12.16%), GII.3 (n = 27, 9.12%), GII.6 (n = 8, 2.7%), GII.4 Sydney_2012 (n = 7, 2.36%), and GII.4 (n = 6, 2.03%).

Conclusions: Our findings illustrate the importance of maintaining epidemiological surveillance for viral gastroenteritis during the COVID-19 pandemic. Local disease prevention and control institutions need to devote sufficient human resources to control norovirus clusters.

School Attendance Registers for the Syndromic Surveillance of Infectious Intestinal Disease in UK Children: Protocol for a Retrospective Analysis

Background

Infectious intestinal disease (IID) is common, and children are more likely than adults both to have IID and to transmit infection onto others. Before the introduction of the vaccine, rotavirus was the leading cause of severe childhood diarrhea, with norovirus and Campylobacter predominate pathogens. Public health surveillance of IID is primarily based on health care data, and as such, illness that is managed within the community will often go undetected. School attendance registers offer a novel data set that has the potential to identify community cases and outbreaks of IID that would otherwise be missed by current health surveillance systems. Although studies have explored the role of school attendance registers in the monitoring of influenza among children, no studies have been identified that consider this approach in the surveillance of IID.

Objective

The aim of this study is to explore the role and utility of school attendance registers in the detection and surveillance of IID in children. The secondary aims are to estimate the burden of IID on school absenteeism and to assess the impact of the rotavirus vaccine on illness absence among school-aged children.

Methods

This study is a retrospective analysis of school attendance registers to investigate whether school absences due to illness can be used to capture seasonal trends and outbreaks of infectious intestinal disease among school-aged children. School absences in Merseyside, United Kingdom will be compared and combined with routine health surveillance data from primary care, laboratories, and telehealth services. These data will be used to model spatial and temporal variations in the incidence of IID and to apportion likely causes to changes in school absenteeism trends. This will be used to assess the potential utility of school attendance data in the surveillance of IID and to estimate the burden of IID absenteeism in schools. It will also inform an analysis of the impact of the rotavirus vaccine on disease within this age group.

Results

This study has received ethical approval from the University of Liverpool Research Ethics Committee (reference number 1819). Use of general practice data has been approved for the evaluation of rotavirus vaccination in Merseyside by NHS Research Ethics Committee, South Central-Berkshire REC Reference 14/SC/1140.

Conclusions

This study is unique in considering whether school attendance registers could be used to enhance the surveillance of IID. Such data have multiple potential applications and could improve the identification of outbreaks within schools, allowing early intervention to reduce transmission both within and outside of school settings. These data have the potential to act as an early warning system, identifying infections circulating within the community before they enter health care settings. School attendance data could also inform the evaluation of vaccination programs, such as rotavirus and, in time, norovirus.

International Registered Report Identifier (IRRID)

DERR1-10.2196/30078

Molecular Epidemiology of Norovirus (NoV) Infection in Mie Prefecture: The Kinetics of Norovirus Antigenemia in Pediatric Patients

Few studies have shown the presence of norovirus (NoV) RNA in blood circulation but there is no data on norovirus antigenemia. We examined both antigenemia and RNAemia from the sera of children with NoV infections and studied whether norovirus antigenemia is correlated with the levels of norovirus-specific antibodies and clinical severity of gastroenteritis. Both stool and serum samples were collected from 63 children admitted to Mie National Hospital with acute NoV gastroenteritis. Norovirus antigen and RNA were detected in sera by ELISA and real-time RT-PCR, respectively. NoV antigenemia was found in 54.8% (34/62) and RNAemia in 14.3% (9/63) of sera samples. Antigenemia was more common in the younger age group (0–2 years) than in the older age groups, and most patients were male. There was no correlation between stool viral load and norovirus antigen (NoV-Ag) levels (r_s = −0.063; Cl −0.3150 to 0.1967; p = 0.6251). Higher levels of acute norovirus-specific IgG serum antibodies resulted in a lower antigenemia OD value (n = 61; r = −0.4258; CI −0.62 to −0.19; p = 0.0006). Norovirus antigenemia occurred more commonly in children under 2 years of age with NoV-associated acute gastroenteritis. The occurrence of antigenemia was not correlated with stool viral load or disease severity.

Evaluation of the virucidal efficacy of Klaran UVC LEDs against surface-dried norovirus

Human norovirus (HuNoV) is a highly contagious pathogenic virus that is transmitted through contaminated food, water, high-touch surfaces and aerosols. Globally, there are an estimated 685 million infections annually due to norovirus, including 200 million affecting children under the age of 5. HuNoV causes approximately 50, 000 child deaths per year and costs an estimated USD $60 billion annually in healthcare. This study sought to determine the inactivation profile of ultraviolet subtype C (UVC) against norovirus using a UVC light-emitting diode (LED) array, KL265-50V-SM-WD. The array emitted radiation at 269 nm peak wavelength and a measured fluence of 1.25 mW cm⁻² at a 7 cm source–surface distance. Since the HuNoV is not cultivable, the study utilized feline calicivirus (FCV) ATCC VR-782, a recommended surrogate as challenge organism. The test followed modified ASTM E2197. Assessment of virus inactivation was performed using a plaque assay method. With irradiance at a UVC dose of 22.5 mJ cm⁻², the study obtained 99.9 % virus reduction (3 log reduction). The results demonstrate that the UVC LED array can provide effective inactivation of HuNoV.

Digestive system involvement and clinical outcomes among COVID-19 patients: A retrospective cohort study from Qatar

BACKGROUND

Coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 virus most commonly presents with respiratory symptoms. While gastrointestinal (GI) manifestations either at presentation or during hospitalization are also common, their impact on clinical outcomes is controversial. Some studies have described worse outcomes in COVID-19 patients with GI symptoms, while others have shown either no association or a protective effect. There is a need for consistent standards to describe GI symptoms in COVID-19 patients and to assess their effect on clinical outcomes, including mortality and disease severity.

AIM

To investigate the prevalence of GI symptoms in hospitalized COVID-19 patients and their correlation with disease severity and clinical outcomes.

METHODS

We retrospectively reviewed 601 consecutive adult COVID-19 patients requiring hospitalization between May 1-15, 2020. GI symptoms were recorded at admission and during hospitalization. Demographic, clinical, laboratory, and treatment data were retrieved. Clinical outcomes included all-cause mortality, disease severity at presentation, need for intensive care unit (ICU) admission, development of acute respiratory distress syndrome, and need for mechanical ventilation. Multivariate logistic regression model was used to identify independent predictors of the adverse outcomes.

RESULTS

The prevalence of any GI symptom at admission was 27.1% and during hospitalization was 19.8%. The most common symptoms were nausea (98 patients), diarrhea (76 patients), vomiting (73 patients), and epigastric pain or discomfort (69 patients). There was no difference in the mortality between the two groups (6.21% vs 5.5%, P = 0.7). Patients with GI symptoms were more likely to have severe disease at presentation (33.13% vs 22.5%, P < 0.001) and prolonged hospital stay (15 d vs 14 d, P = 0.04). There was no difference in other clinical outcomes, including ICU admission, development of acute respiratory distress syndrome, or need for mechanical ventilation. Drugs associated with the development of GI symptoms during hospitalization were ribavirin (diarrhea 26.37% P < 0.001, anorexia 17.58%, P = 0.02), hydroxychloroquine (vomiting 28.52%, P = 0.009) and lopinavir/ritonavir (nausea 32.65% P = 0.049, vomiting 31.47% P = 0.004, and epigastric pain 12.65% P = 0.048). In the multivariate regression analysis, age > 65 years was associated with increased mortality risk [odds ratio (OR) 7.53, confidence interval (CI): 3.09-18.29, P < 0.001], ICU admission (OR: 1.79, CI: 1.13-2.83, P = 0.012), and need for mechanical ventilation (OR: 1.89, CI:1.94-2.99, P = 0.007). Hypertension was an independent risk factor for ICU admission (OR: 1.82, CI:1.17-2.84, P = 0.008) and need for mechanical ventilation (OR: 1.66, CI: 1.05-2.62, P = 0.028).

CONCLUSION

Patients with GI symptoms are more likely to have severe disease at presentation; however, mortality and disease progression is not different between the two groups.

Norovirus strains among children aged 0-18 years hospitalized with acute gastroenteritis in Estonia 2015-2016

Norovirus (NoV) is the leading cause of acute gastroenteritis (AGE) in many countries that have introduced universal rotavirus mass vaccination. This is the first study to report data on NoV strains in Estonia. We recruited 2249 children aged 0-18 years hospitalized for AGE in Estonian hospitals from February 1, 2015 to August 31, 2016. Norovirus gastroenteritis (NoVGE) was diagnosed in 14.5% (n = 325) cases. Stool sample for RNA extraction and genotyping was available in 86% (n = 280) of NoVGE cases (2015, n = 91; 2016, n = 189). Dominant capsid types detected in 75% (n = 210) samples were, GII.4 (63.8%, n = 134), GII.3 (15.2%, n = 32), GII.17 (6.7%, n = 14), and GII.6 (5.2%, n = 11). Prevailing RNA polymerase types found in 77% (n = 215) samples were GII.P31 (51.1%, n = 110), GII.P21 (17.7%, n = 38), GII.P4 (11.2%, n = 24), and GII.P7 (6.5%, n = 14). Both regions were typeable for 67% (n = 189) of samples. Most prevalent strains were GII.4Sydney_2012[P31] (48.7%, n = 92), GII.3[P21] (15.3%, n = 29), GII.4Sydney_2012[P4] (5.8%, n = 11) and GII.17[P17] (5.8%, n = 11). Simpson's diversity index showed a significant difference between the age groups 1-4 and 5-9 years: D 0.64 (95% confidence interval [CI]: 0.55-0.73) versus 0.83 (95% CI: 0.81-0.86), respectively (p = 0.03). An accurate understanding of NoV strain diversity is important for control and preventive measures, especially in the postrotavirus vaccine era.

Development of a Specific Anti-capsid Antibody- and Magnetic Bead-Based Immunoassay to Detect Human Norovirus Particles in Stool Samples and Spiked Mussels via Flow Cytometry

Human noroviruses impose a considerable health burden globally. Here, a flow cytometry approach designed for their detection in biological waste and food samples was developed using antibody-coated magnetic beads. Antipeptide antibodies against murine norovirus and various human norovirus genotypes were generated for capture and coated onto magnetic beads. A flow cytometry assay was then implemented to detect bead-bound human norovirus GI.3 in patient stool samples and in norovirus-spiked mussel digestive tissues. The detection limit for stool samples was 10⁵ gc/mL, thus bettering detection limits of commercially available norovirus diagnosis quick kits of 100-fold; the detection limit in spiked mussels however was ten-fold higher than in stool samples. Further assays showed a decrease in fluorescence intensity for heat- or UV-inactivated virus particles. Overall, we demonstrate the application of a flow cytometry approach for direct detection of small non-enveloped virus particles such as noroviruses. An adaptation of the technology to routine diagnostics has the potential to contribute a rapid and sensitive tool to norovirus outbreak investigations. Further improvements to the method, notably decreasing the detection limit of the approach, may allow the analysis of naturally contaminated food and environmental samples.

Prevalence, Distribution, and Genotypes of Adenovirus and Norovirus in the Puzi River and Its Tributaries and the Surrounding Areas in Taiwan

This study investigated the prevalence, distribution, and genotypes of adenoviruses (AdVs) and noroviruses (NoVs) in the Puzi River and surrounding areas in Taiwan. The viruses in the water samples were isolated using the membrane filtration method and the viral nucleic acids were extracted. The RNA of NoVs was reverse-transcribed into complementary DNA using reverse transcriptase-polymerase chain reaction. AdVs and NoVs were detected using nested PCR. Genotyping and phylogenetic analyses were performed to identify the various viral genotypes in the water samples. Human adenovirus (HAdVs) and porcine adenovirus (PAdVs) were the predominant genotypes in the water samples. The prevalence of F species HAdVs serotype 41 (79.2%) and C species PAdVs serotype 5 (18.1%) was higher than that of other serotypes. Among NoVs, genogroup GII was more prevalent than GI. In particular, GII.4 (21.2%) and GII.17 (18.2%) were the predominant genotypes, which was consistent with the clinical findings. The prevalence of both AdVs and NoVs was higher in the winter than spring, summer and autumn seasons. AdVs and NoVs detection results were statistically analyzed by investigating their association with water quality indicators. The results revealed that the presence of AdVs was significantly correlated with the heterotrophic bacterial count, total coliform Escherichia coli, turbidity, salinity, and dissolved oxygen. Meanwhile, the presence of NoVs was only significantly correlated with temperature, pH, and dissolved oxygen. Microbial pollution sources may include urban runoff and discharge of water from livestock farms situated near the river and tributaries within this region of Taiwan. Future studies should include comparisons of the presence of AdVs and NoVs in these known pollution sources and water quality monitoring of these watersheds, as this will allow potential identification of pollution sources. Additionally, remediation strategies must be developed to minimize viral contamination in the river ecosystem.

Investigation and analysis on an outbreak of norovirus infection in a health school in Guangdong Province, China

Our objective was to describe the epidemiological features of an outbreak of norovirus infection in a health school in Guangdong province, China, to identify the cause of such a large scale outbreak of norovirus among older students, to simulate the transmission dynamics, and to evaluate the effect of intervention measures of GII.17 [P17] genotype norovirus infection. We identified all cases during the outbreak. Descriptive epidemiological, analytical epidemiological and hygiene survey methods were used to described the outbreak epidemic course and identify the cause of the outbreak of norovirus infection. We also used dynamical model to simulate the transmission dynamics of norovirus infection and evaluate the effect of intervention measures. Norovirus genotyping was assigned to the newly obtained strains, with a maximum likelihood phylogenetic analysis conducted. There were 360 cases of 42 classes in five grades with a 12.99% attack rate. Proportionally, more students were in contact with sick students and vomit in the suspected case group than the control group (χ² = 5.535, P = 0.019 and χ² = 5.549, P = 0.019, respectively). The basic reproduction number was 8.32 before and 0.49 after the intervention. Dynamical modeling showed that if the isolation rate was higher or case isolation began earlier, the total attack rate would decrease. Molecular characterization identified the GII.17 [P17] genotype in all stains obtained from the health school, which were clustered with high support in the phylogenetic tree. This was an outbreak of norovirus infection caused by contact transmission. The main reasons for the spread of the epidemic were the later control time, irregular treatment of vomit and no case isolation. The transmission dynamics of contact transmission was high, more efficient control measures should be employed.

Mass Spectrometry-Based System for Identifying and Typing Norovirus Major Capsid Protein VP1

Norovirus-associated diseases are the most common foodborne illnesses worldwide. Polymerase chain reaction-based methods are the primary diagnostics for clinical samples; however, the high mutation rate of norovirus makes viral amplification and genotyping challenging. Technological advances in mass spectrometry (MS) make it a promising tool for identifying disease markers. Besides, the superior sensitivity of MS and proteomic approaches may enable the detection of all variants. Thus, this study aimed to establish an MS-based system for identifying and typing norovirus. We constructed three plasmids containing the major capsid protein VP1 of the norovirus GII.4 2006b, 2006a, and 2009a strains to produce virus-like particles for use as standards. Digested peptide signals were collected using a nano-flow ultra-performance liquid chromatography mass spectrometry (nano-UPLC/MS^E) system, and analyzed by ProteinLynx Global SERVER and TREE-PUZZLE software. Results revealed that the LC/MS^E system had an excellent coverage rate: the system detected more than 94% of amino acids of 3.61 femtomole norovirus VP1 structural protein. In the likelihood-mapping analysis, the proportions of unresolved quartets were 2.9% and 4.9% in the VP1 and S domains, respectively, which is superior to the 15.1% unresolved quartets in current PCR-based methodology. In summary, the use of LC/MS^E may efficiently monitor genotypes, and sensitively detect structural and functional mutations of noroviruses.

Akt plays differential roles during the life cycles of acute and persistent murine norovirus strains in macrophages

Akt (Protein kinase B) is a key signaling protein in eukaryotic cells that controls many cellular processes such as glucose metabolism and cell proliferation for survival. As obligate intracellular pathogens, viruses modulate host cellular processes, including Akt signaling, for optimal replication. The mechanisms by which viruses modulate Akt and the resulting effects on the infectious cycle differ widely depending on the virus. In this study, we explored the effect of Akt serine 473 phosphorylation (p-Akt) during murine norovirus (MNV) infection. p-Akt increased during infection of murine macrophages with acute MNV-1 and persistent CR3 and CR6 strains. Inhibition of Akt with MK2206, an inhibitor of all three isoforms of Akt (Akt1/2/3), reduced infectious virus progeny of all three virus strains. This reduction was due to decreased viral genome replication (CR3), defective virus assembly (MNV-1), or diminished cellular egress (CR3 and CR6) in a virus strain-dependent manner. Collectively, our data demonstrate that Akt activation increases in macrophages during the later stages of the MNV infectious cycle, which may enhance viral infection in unique ways for different virus strains. The data, for the first time, indicate a role for Akt signaling in viral assembly and highlight additional phenotypic differences between closely related MNV strains. Importance Human noroviruses (HNoV) are a leading cause of viral gastroenteritis, resulting in high annual economic burden and morbidity; yet there are no small animal models supporting productive HNoV infection, or robust culture systems producing cell culture-derived virus stocks. As a result, research on drug discovery and vaccine development against norovirus infection has been challenging, and no targeted antivirals or vaccines against HNoV are approved. On the other hand, murine norovirus (MNV) replicates to high titers in cell culture and is a convenient and widespread model in norovirus research. Our data demonstrate the importance of Akt signaling during the late stage of the MNV life cycle. Notably, the effect of Akt signaling on genome replication, virus assembly and cellular egress is virus strain specific, highlighting the diversity of biological phenotypes despite small genetic variability among norovirus strains. This study is the first to demonstrate a role for Akt in viral assembly.

Vinyl-Stilbene Inhibits Human Norovirus RNA Replication by Activating Heat-Shock Factor-1

Norovirus (NV) is the most common cause of viral gastroenteritis, with the potential to develop into a fatal disease in those who are immuno-compromised, and effective vaccines and treatments are still non-existent. In this study, we aimed to elucidate the molecular mechanism of the previously identified NV replication inhibitor utilizing a vinyl-stilbene backbone, AC-1858. First, we confirmed the inhibition of the NV RNA replication by a structural analog of AC-1858, AC-2288 with its exclusive cytoplasmic subcellular localization. We further validated the induction of one specific host factor, the phosphorylated form of heat shock factor (HSF)-1, and its increased nuclear localization by AC-1858 treatment. Finally, we verified the positive and negative impact of the siRNA-mediated downregulation and lentivirus-mediated overexpression of HSF-1 on NV RNA replication. In conclusion, these data suggest the restrictive role of the host factor HSF-1 in overall viral RNA genome replication during the NV life cycle.

Two-step purification of tag-free norovirus-like particles from silkworm larvae (Bombyx mori)

Recombinantly expressed VP1 of norovirus self-assembled and formed norovirus-like particles (NoV-LPs). This native VP1 was expressed using the Bombyx mori nucleopolyhedrovirus (BmNPV) expression system in silkworm larva. NoV-LPs were collected from silkworm fat body lysate by density gradient centrifugation. To improve the purity of the NoV-LP, the proteins were further purified using immobilized metal affinity chromatography based on the surface exposed side chain of histidine residues. The additional purification led to a highly purified virus-like particle (VLP). The morphology and size of the purified VLPs were examined using a transmission electron microscope, and dynamic light scattering revealed a monodispersed spherical morphology with a diameter of 34 nm. The purified product had a purity of >90% with a recovery yield of 48.7% (equivalent to 930 μg) from crude lysate, obtained from seven silkworm larvae. In addition, the purified VLP could be recognized by antibodies against GII norovirus in sandwich enzyme-linked immunosorbent assay, which indicated that the silkworm-derived VLP is biologically functional as a NoV-LP in its native state, is structurally correct, and exerts its biological function. Our results suggest that the silkworm-derived NoV-LP may be useful for subsequent applications, such as in a vaccine platform. Moreover, the silkworm-based expression system is known for its robustness, facile up-scalability, and relatively low expense compared to insect cell systems.

A norovirus gastroenteritis outbreak in an Australian child-care center: A household-level analysis

There is a large burden of norovirus disease in child-care centers in Australia and around the world. Despite the ubiquity of norovirus outbreaks in child-care centers, little is known about the extent of this burden within the child-care center and the surrounding household clusters. Therefore, we performed an in-depth analysis of a gastroenteritis outbreak to examine the patterns of transmissions, household attack rates and the basic reproduction number (R0) for Norovirus in a child-care facility. We used data from parental interviews of suspected cases sent home with gastroenteritis at a child-care center between 24th of August and 18th of September 2020. A total of 52 persons in 19 household clusters were symptomatic in this outbreak investigation. Of all transmissions, 23 (46.9%) occurred in the child-care center, the rest occurring in households. We found a household attack rate of 36.5% (95% CI 27.3, 47.1%). Serial intervals were estimated as mean 2.5 ± SD1.45 days. The R0, using time-dependent methods during the growth phase of the outbreak (days 2 to 8) was 2.4 (95% CI 1.50, 3.50). The count of affected persons of a child-care center norovirus outbreak is approximately double the count of the total symptomatic staff and attending children. In the study setting, each symptomatic child-care attendee likely infected one other child-care attendee or staff and just over one household contact on average.

Norovirus GII.2[P16] strain in Shenzhen, China: a retrospective study

Background

Norovirus (NoV) is the main cause of non-bacterial acute gastroenteritis (AGE) outbreaks worldwide. From September 2015 through August 2018, 203 NoV outbreaks involving 2500 cases were reported to the Shenzhen Center for Disease Control and Prevention.

Methods

Faecal specimens for 203 outbreaks were collected and epidemiological data were obtained through the AGE outbreak surveillance system in Shenzhen. Genotypes were determined by sequencing analysis. To gain a better understanding of the evolutionary characteristics of NoV in Shenzhen, molecular evolution and mutations were evaluated based on time-scale evolutionary phylogeny and amino acid mutations.

Results

A total of nine districts reported NoV outbreaks and the reported NoV outbreaks peaked from November to March. Among the 203 NoV outbreaks, 150 were sequenced successfully. Most of these outbreaks were associated with the NoV GII.2[P16] strain (45.3%, 92/203) and occurred in school settings (91.6%, 186/203). The evolutionary rates of the RdRp region and the VP1 sequence were 2.1 × 10^–3 (95% HPD interval, 1.7 × 10^–3–2.5 × 10^–3) substitutions/site/year and 2.7 × 10^–3 (95% HPD interval, 2.4 × 10^–3–3.1 × 10^–3) substitutions/site/year, respectively. The common ancestors of the GII.2[P16] strain from Shenzhen and GII.4 Sydney 2012[P16] diverged from 2011 to 2012. The common ancestors of the GII.2[P16] strain from Shenzhen and previous GII.2[P16] (2010–2012) diverged from 2003 to 2004. The results of amino acid mutations showed 6 amino acid substitutions (*77E, R750K, P845Q, H1310Y, K1546Q, T1549A) were found only in GII.4 Sydney 2012[P16] and the GII.2[P16] recombinant strain.

Conclusions

This study illustrates the molecular epidemiological patterns in Shenzhen, China, from September 2015 to August 2018 and provides evidence that the epidemic trend of GII.2[P16] recombinant strain had weakened and the non-structural proteins of the recombinant strain might have played a more significant role than VP1.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06746-9.

Interferon responses to norovirus infections: current and future perspectives

Human noroviruses (HuNoVs) are increasingly becoming the main cause of transmissible gastroenteritis worldwide, with hundreds of thousands of deaths recorded annually. Yet, decades after their discovery, there is still no effective treatment or vaccine. Efforts aimed at developing vaccines or treatment will benefit from a greater understanding of norovirus-host interactions, including the host response to infection. In this review, we provide a concise overview of the evidence establishing the significance of type I and type III interferon (IFN) responses in the restriction of noroviruses. We also critically examine our current understanding of the molecular mechanisms of IFN induction in norovirus-infected cells, and outline the diverse strategies deployed by noroviruses to supress and/or avoid host IFN responses. It is our hope that this review will facilitate further discussion and increase interest in this area.

Global prevalence of norovirus in cases of acute gastroenteritis from 1997 to 2021: An updated systematic review and meta-analysis

BACKGROUND

The worldwide response towards the acute gastroenteritis epidemic was well known, but the absence of an updated systematic review of global norovirus epidemiology in cases of gastroenteritis existed. We aimed to conduct and update a systematic review and meta-analysis of studies assessing norovirus prevalence among gastroenteritis patients worldwide.

METHODS

Four databases (PubMed, EMBASE, Cochrane Library, and Web of Science) were searched for epidemiological papers from 2014 to 2021 which applied the PCR method to access the prevalence of norovirus in acute gastroenteritis patients more than a full year. Statistical analysis was conducted using R-4.0.0 software.

RESULTS

A total of 405 records with 842, 926 cases were included. The pooled prevalence of norovirus was 16% (95%CI 15, 17). Children under 5 years old were at a higher risk with norovirus. A higher prevalence was seen in South America (22%, 95% CI 18, 27), while other continents showed a similar result with the overall prevalence of norovirus. No association was found between national income level and norovirus prevalence. A gradient of decreasing prevalence was noticed from community (20%, 95% CI 16, 24) to outpatients (18%, 95% CI 16, 20) to hospital setting (included both in- and outpatients, 17%, 95% CI 16, 19) to inpatients (15%, 95% CI 13, 17).

CONCLUSION

Norovirus were associated with 16% acute gastroenteritis globally. To fully understand the prevalence of norovirus worldwide, the continual surveillance of norovirus epidemics was required.

Epidemiology of norovirus and viral gastroenteritis in Ontario, Canada, 2009-2014

BACKGROUND

Norovirus is the most common cause of acute gastroenteritis in Canada. The illness causes great morbidity and high societal costs. The objective of this article is to describe the epidemiology of norovirus in the province of Ontario, Canada from 2009 to 2014.

METHODS

To assess activity of norovirus and viral gastroenteritis (VGE) in Ontario, three datasets were acquired from the provincial government: two traditional surveillance datasets (outbreak and laboratory) and syndromic surveillance data (telehealth), all spanning 2009-2014. All outbreaks, laboratory submissions and telehealth calls were first assessed for total VGE. Norovirus and norovirus-like illness totals were calculated as a proportion of VGE to estimate agent-specific activity levels. Affected institution types, sexes and age groups were also analyzed.

RESULTS

Between 2009 and 2014, 41.5% of VGE outbreaks, 63.4% of VGE laboratory submissions and 36.6% of all acute gastroenteritis-related (not restricted to viral causes) telehealth calls were attributed to norovirus and norovirus-like illness in Ontario. The most commonly affected institution type was long-term care homes and the most commonly affected age groups were younger (younger than five years) and older (older than 65 years) individuals. Females were slightly more frequently affected than males.

CONCLUSION

Norovirus and norovirus-like illnesses were the leading cause of VGE in Ontario between 2009 and 2014. They comprised the greatest percentage of VGE when compared with all other VGE-associated viruses. Additional work is needed to determine all component costs and necessary public health actions to reduce the burden of disease.

An Increased Risk of School-Aged Children with Viral Infection among Diarrhea Clusters in Taiwan during 2011-2019

Acute diarrhea is mainly caused by norovirus and rotavirus. Numerous factors modify the risk of diarrhea cluster infections and outbreaks. The purpose of this study was to explore the epidemiological characteristics, differences, and trends in the distribution of viral and bacterial pathogens that cause diarrhea cluster events as well as the public places where diarrhea cluster events took place in Taiwan from 2011 to 2019. We examined publicly available, annual summary data on 2865 diarrhea clusters confirmed by the Taiwan Centers for Disease Control (CDC) from 2011 to 2019. There were statistically significant differences (p < 0.001) in event numbers of diarrhea clusters among viral and bacterial pathogens, and statistically significant differences (p < 0.001) in event numbers of diarrhea clusters among bacterial pathogens. There were also statistically significant differences (p < 0.001) in the event numbers of diarrhea clusters among public places. Norovirus infections were the first most numerous (77.1%, 1810/2347) diarrhea clusters among viral and bacterial infections. Among bacterial infections, Staphylococcus aureus infections accounted for the greatest number of diarrhea clusters (35.5%, 104/293). Schools were the places with the greatest number of diarrhea clusters (49.1%, 1406/2865) among various institutions. Norovirus single infection (odds ratio, OR = 4.423), Staphylococcus aureus single infection (OR = 2.238), and school (OR = 1.983) were identified as risk factors. This is the first report of confirmed events of diarrhea clusters taken from surveillance data compiled by Taiwan's CDC (2011-2019). This study highlights the importance of long-term and geographically extended studies, particularly for highly fluctuating pathogens, to understand the implications of the transmission of diarrhea clusters in Taiwan's populations. Importantly, big data have been identified that can inform future surveillance and research efforts in Taiwan.

High proportion of norovirus infection and predominance of GII.3 [P12] genotype among the children younger than 5 in Sabah, Malaysian Borneo

Globally, norovirus (NoV) has become one of the important causes of acute gastroenteritis (AGE) in children. It is responsible for death of children younger than 5 years in developing countries. Although there is limited information and the rate of child mortality caused by diarrhea is low in Malaysia, the burden of diarrhea is high, especially in Sabah. NoV GI, GII and GIV genogroups are known to infect humans, and GII.4 is the predominant genotype distributed worldwide. Better understanding of the etiology of NoV will help to inform policies for prevention and control. The aim of this study was to determine the burden and genotype distribution of NoV in children younger than 5 years with AGE who attended health-care facilities in Sabah, Malaysia. Diarrhea stool samples were collected from 299 children with AGE and NoV was detected by amplifying the capsid and RNA-dependent RNA polymerase gene and reverse transcription-polymerase chain reaction (RT-PCR) analysis. Nucleotide sequencing of the amplicons was used for genotypes and phylogenetic analyses . NoV-positive stool samples were found in 17.7% (53/299) among which 13/53 (24.5%), 38/53 (71.7%), and 2/53 (3.8%) identified as NoV GI, GII and combination of GI and GII, respectively. The most common genotypes were GII.3 [P12] (80%) followed by GII.6 [P7] (13.3%), and GII.17 [P17] (6.7%). In the phylogenetic tree, all Sabahan NoV samples were shown to share ancestry with their respective genotype from predominantly East Asian countries and to some extent Australia and Europe. However, the Sabahan strains formed independent clusters with significant bootstrap values, indicating a clonal spread after the strains had entered Sabah.

Diagnostic Accuracy of Immunochromatographic Tests for the Detection of Norovirus in Stool Specimens: a Systematic Review and Meta-Analysis

Noroviruses are the leading cause of acute gastroenteritis in all age groups and constitute a major health and economic burden worldwide. This systematic review and meta-analysis aimed to determine the diagnostic accuracy of immunochromatographic tests (ICTs) for the detection of norovirus in stool specimens, which has not been performed previously. In this systematic review and meta-analysis (registered on PROSPERO, CRD42020186911), we searched Medline/PubMed, Embase, Cochrane Library, and Web of Science for all studies published up to 16 May 2020. The values for sensitivity, specificity, positive likelihood ratio (LR+), negative likelihood ratio (LR-), and diagnostic odds ratio (DOR) of ICTs with 95% confidence interval (CI) were pooled using a bivariate random-effects model. The summary receiver operating characteristic curve and area under the curve were used to summarize overall test accuracy. We included 43 studies describing 7,428 samples. The overall estimates of sensitivity, specificity, LR+, LR-, DOR, and accuracy of ICT for diagnosing norovirus were 0.61 (95% CI, 0.54 to 0.67), 0.97 (95% CI, 0.95 to 0.98), 17.08 (95% CI, 11.15 to 26.18), 0.40 (95% CI, 0.34 to 0.46), 53.9 (95% CI, 31.32 to 92.78), and 0.928, respectively. Significant differences in pooled sensitivities were noted between age groups and in pooled DOR and LR+ between genogroups of included samples. ICT provides low sensitivity but high specificity and accuracy for detecting norovirus. Thus, an ICT for norovirus can be a rapid and convenient way for identifying patients early; however, a negative result cannot rule out norovirus infection and should be confirmed by a reference test.

Clinical Profiles of Childhood Astrovirus-, Sapovirus-, and Norovirus-Associated Acute Gastroenteritis in Pediatric Emergency Departments in Alberta, 2014-2018

BACKGROUND

Infections by previously underdiagnosed viruses astrovirus and sapovirus are poorly characterized compared with norovirus, the most common cause of acute gastroenteritis.

METHODS

Children <18 years old with acute gastroenteritis were recruited from pediatric emergency departments in Alberta, Canada between 2014 and 2018. We described and compared the clinical course of acute gastroenteritis in children with astrovirus, sapovirus, and norovirus.

RESULTS

Astrovirus was detected in 56 of 2688 (2.1%) children, sapovirus was detected in 146 of 2688 (5.4%) children, and norovirus was detected in 486 of 2688 (18.1%) children. At illness onset, ~60% of astrovirus cases experienced both diarrhea and vomiting. Among sapovirus and norovirus cases, 35% experienced diarrhea at onset and 80% of 91% (sapovirus/norovirus) vomited; however, diarrhea became more prevalent than vomiting at approximately day 4 of illness. Over the full course of illness, diarrhea was 18% (95% confidence interval [CI], 8%- 29%) more prevalent among children with astrovirus than norovirus infections and had longer duration with greater maximal events; there were a median of 4.0 fewer maximal vomiting events (95% CI, 2.0-5.0). Vomiting continued for a median of 24.8 hours longer (95% CI, 9.6-31.7) among children with sapovirus versus norovirus. Differences between these viruses were otherwise minimal.

CONCLUSIONS

Sapovirus infections attended in the emergency department are more similar to norovirus than previously reported, whereas astrovirus infections have several distinguishable characteristics.

Risk factors for norovirus infection in healthcare workers during nosocomial outbreaks: a cross-sectional study

Background

Norovirus outbreaks cause severe medico-socio-economic problems affecting healthcare workers and patients. The aim of the study was to investigate prevalence of norovirus infection and risk factors for infection in healthcare workers during nosocomial outbreaks.

Methods

A cross-sectional study of norovirus infections in healthcare workers was performed in seven outbreak wards in a large university hospital. Packs (swab for rectal sampling, and questionnaire) were posted to healthcare workers on notification of a ward outbreak. Rectal samples were examined with norovirus-specific real-time PCR. Replies from questionnaires were analysed using logistic regression models with norovirus genogroup (G)II positive findings as dependent variable. The results are expressed as odds ratios (OR) with 95% confidence intervals (CI). Sequencing and phylogenetic analyses (1040 nucleotides) were used to characterize norovirus strains from healthcare workers. Cluster analyses included norovirus GII.4 strains detected in ward patients during the ongoing outbreaks.

Results

Of 308 packs issued to healthcare workers, 129 (42%) were returned. norovirus GII was detected in 26 healthcare workers (20.2%). Work in cohort care (OR 4.8, 95% CI 1.4–16.3), work in wards for patients with dementia (OR 13.2, 95% CI 1.01–170.7), and having diarrhoea, loose stools or other gastrointestinal symptoms the last week (OR 7.7, 95% CI 2.5–27.2) were associated with increased norovirus prevalence in healthcare workers. Sequencing revealed norovirus GII.4 in healthcare workers samples, and strains detected in healthcare workers and ward patients during a given ward outbreak showed ≥ 99% similarity.

Conclusion

Norovirus positive findings in healthcare workers were strongly associated with symptomatic infection, close contact with sick patients, and dementia nursing.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-021-00979-8.

Nanotechnology-based Colorimetric Approaches for Pathogenic Virus Sensing: A review

Fast and inexpensive virus identification protocols are paramount to hinder the further extent of pandemic diseases, minimize economic and social damages, and expedite proper clinical rehabilitation. Until now, various biosensors have been fabricated for the identification of pathogenic particles. But, they offer many difficulties. Nanotechnology resolves these difficulties and offers direct identification of pathogenic species in real-time. Among them, nanomaterial based-colorimetric sensing approach of pathogenic viruses by the naked eye has attracted much awareness because of their simplicity, speed, and low cost. In this review, the latest tendencies and advancements are overviewed in detecting pathogenic viruses using colorimetric concepts. We focus on and reconsider the use of distinctive nanomaterials such as metal nanoparticles, carbon nanotubes, graphene oxide, and conducting polymer to form colorimetric pathogenic virus sensors.

Norovirus in Cancer Patients: A Review

Norovirus (NoV) is the leading cause of viral-related diarrhea in cancer patients, in whom it can be chronic, contributing to decreased quality of life, interruption of cancer care, malnutrition, and altered mucosal barrier function. Immunosuppressed cancer patients shed NoV for longer periods of time than immunocompetent hosts, favoring quasispecies development and emergence of novel NoV variants. While nucleic acid amplification tests (NAATs) for NoV diagnosis have revolutionized our understanding of NoV burden of disease, not all NAATs provide information on viral load or infecting genotype. There is currently no effective antiviral or vaccine for chronic NoV infections. Screening for inhibitors of NoV replication in intestinal organoid culture models and creation of NoV-specific adoptive T cells are promising new strategies to develop treatments for chronic NoV in immunosuppressed patients. Herein we summarize data on the epidemiology, clinical manifestations, diagnostic challenges, and treatment of NoV infection in patients with cancer.

Antiviral Activity Exerted by Natural Products against Human Viruses

Viral infections are responsible for several chronic and acute diseases in both humans and animals. Despite the incredible progress in human medicine, several viral diseases, such as acquired immunodeficiency syndrome, respiratory syndromes, and hepatitis, are still associated with high morbidity and mortality rates in humans. Natural products from plants or other organisms are a rich source of structurally novel chemical compounds including antivirals. Indeed, in traditional medicine, many pathological conditions have been treated using plant-derived medicines. Thus, the identification of novel alternative antiviral agents is of critical importance. In this review, we summarize novel phytochemicals with antiviral activity against human viruses and their potential application in treating or preventing viral disease.

Efficacy of compartmentalization in controlling an adenovirus type 54 keratoconjunctivitis outbreak on Oki Island, Japan

PURPOSE

To analyze the epidemiologic characteristics of an outbreak of human adenovirus type 54 (HAdV-54) on Oki Island, Shimane Prefecture, Japan, in 2017 and to assess the effectiveness of a compartmentalization method in controlling the incidence and spread.

STUDY DESIGN

Retrospective cohort study.

METHODS

The infection was diagnosed in 136 individuals, and typing was confirmed by PCR and direct sequencing. The epidemiologic characteristics of the disease including the infection rate, incubation period, and basic reproductive number (R0), ie, number of cases directly infected by an infectious patient during the course of the disease, were investigated. The effectiveness of compartmentalization for infection control was determined by simulating the outbreak using the Susceptible-Exposed-Infectious-Recovered (SEIR) model.

RESULTS

The majority of the HAdV-54-infected individuals were the children of 3 nursery schools (A, B, and C) and their parents on Oki Island. The infection rates in the 3 schools were 13.2%, 16.9%, and 17.2%, respectively. The one class of school B without the index case was initially compartmentalized, and the infection rate in this compartment was 0%. The incubation period was calculated to be 9.3 ± 3.5 days, and the disease duration, 13.0 ± 5.4 days. The R0 was 1.43. Using these parameters, a SEIR model was constructed. The SEIR model well predicted the daily incidence of infection and indicated that the compartmentalization method provides effective reduction in the incidence of the infection, with much earlier control.

CONCLUSIONS

The compartmentalization method is effective to control HAdV-54 outbreaks.

Homotypic and Heterotypic Protection and Risk of Reinfection Following Natural Norovirus Infection in a Highly Endemic Setting

BACKGROUND

Norovirus is a leading cause of acute gastroenteritis worldwide, yet there is limited information on homotypic or heterotypic protection following natural infection to guide vaccine development.

METHODS

A total of 6020 stools collected from 299 Peruvian children between 2010 and 2014 were tested by norovirus real-time reverse-transcription polymerase chain reaction followed by sequence-based genotyping. Cox proportional hazards models were used to derive adjusted hazard ratios (HRs) of infection among children with vs without prior exposure.

RESULTS

Norovirus was detected in 1288 (21.3%) samples. GII.4 (26%), GII.6 (19%), and GI.3 (9%) viruses accounted for 54% of infections. Homotypic protection for GI.3 (HR, 0.35; P = .015), GI.7 (HR, 0.19; P = .022), GII.4 (HR, 0.39; P < .001), and GII.6 (HR, 0.52; P = .006) infections was observed. Hazard analysis showed that children with prior GII.4 infection exhibited heterotypic protection with a 48% reduction of subsequent GI.3 infection (HR, 0.52; P = .005). Prior exposure to GI.3, GII.2, and GII.17 infections enhanced susceptibility to subsequent infections with several other norovirus genotypes.

CONCLUSIONS

Children up to 2 years of age infected with GII.4 noroviruses demonstrated both homotypic and heterotypic protection to reinfection with other genotypes. These data support the need for ongoing vaccine development efforts with GII.4 as the main component and caution the inclusion of genotypes that may enhance susceptibility to infections.

First detection of canine norovirus in dogs and a complete GVI.2 genome in mainland China

Canine norovirus (CNV) is a diarrhea-causing pathogen in canines. In this study, 268 canine diarrheic fecal samples were collected from 13 pet hospitals across three provinces in China between March 2017 and May 2019, and 7.8% (21/268) samples were detected as CNV-positive by RT-PCR. Phylogenetic analysis of twenty-one CNV RdRp fragments showed that eighteen of the strains clustered in GVI.2, two clustered in GVI.1 and one clustered in GIV.2. The complete RdRp, VP1, and VP2 genes of four GVI.2 strains obtained from three provinces were successfully sequenced. Phylogenetic analyses based on the RdRp, VP1, and VP2 genes showed that the GVI.2 strains from this study were closely related to USA GVI.2 strains. The complete genome of GVI.2 strain Dog/M9/18/CH was successfully sequenced, it was 7905 nucleotides (nt) in length and shared 95.9% nt identity with the sole available, nearly full-length genome of GVI.2 strain genome. To our knowledge, this is first description of the molecular prevalence of CNV in mainland China, and the first report of a complete GVI.2 genome. These findings will extend our understanding of epidemics and the genetic evolution of CNV.

Clinical characteristics, risk factors and outcome of severe Norovirus infection in kidney transplant patients: a case-control study

Background

Human Norovirus (HuNoV) has recently been identified as a major cause of diarrhea among kidney transplant recipients (KTR). Data regarding risk factors associated with the occurrence of HuNoV infection, and its long-term impact on kidney function are lacking.

Methods

We conducted a retrospective case-control study including all KTR with a diagnosis of HuNoV diarrhea. Each case was matched to a single control according to age and date of transplantation, randomly selected among our KTR cohort and who did not develop HuNoV infection. Risk factors associated with HuNoV infection were identified using conditional logistic regression, and survival was estimated using Kaplan-Meier estimator.

Results

From January 2012 to April 2018, 72 cases of NoV diarrhea were identified among 985 new KT, leading to a prevalence of HuNoV infection of 7.3%. Median time between kidney transplantation and diagnosis was 46.5 months (Inter Quartile Range [IQR]:17.8–81.5), and the median duration of symptoms 40 days (IQR: 15–66.2). Following diagnosis, 93% of the cases had a reduction of immunosuppression. During follow-up, de novo Donor Specific Antibody (DSA) were observed in 8 (9%) cases but none of the controls (p = 0.01). Acute rejection episodes were significantly more frequent among cases (13.8% versus 4.2% in controls; p = 0,03), but there was no difference in serum creatinine level at last follow-up between the two groups (p = 0.08). Pre-transplant diabetes and lymphopenia below 1000/mm³ were identified as risks factors for HuNoV infection in multivariate analysis.

Conclusion

HuNoV infection is a late-onset and prolonged infection among KTR. The current management, based on the reduction of immunosuppressive treatment, is responsible for the appearance of de novo DSA and an increase in acute rejection episodes.

Potential intestinal infection and faecal-oral transmission of SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread to more than 200 countries and regions globally. SARS-CoV-2 is thought to spread mainly through respiratory droplets and close contact. However, reports have shown that a notable proportion of patients with coronavirus disease 2019 (COVID-19) develop gastrointestinal symptoms and nearly half of patients confirmed to have COVID-19 have shown detectable SARS-CoV-2 RNA in their faecal samples. Moreover, SARS-CoV-2 infection reportedly alters intestinal microbiota, which correlated with the expression of inflammatory factors. Furthermore, multiple in vitro and in vivo animal studies have provided direct evidence of intestinal infection by SARS-CoV-2. These lines of evidence highlight the nature of SARS-CoV-2 gastrointestinal infection and its potential faecal-oral transmission. Here, we summarize the current findings on the gastrointestinal manifestations of COVID-19 and its possible mechanisms. We also discuss how SARS-CoV-2 gastrointestinal infection might occur and the current evidence and future studies needed to establish the occurrence of faecal-oral transmission.

Molecular Evolution of Human Norovirus GII.2 Clusters

Background

The human norovirus GII.2 outbreak during the 2016–2017 winter season was of unprecedented scale and geographic distribution.

Methods

We analyzed 519 complete VP1 gene sequences of the human norovirus GII.2 genotype sampled during the 2016–2017 winter season, as well as prior (dating back to 1976) from 7 countries. Phylodynamic analyses of these sequences were performed using maximum likelihood and Bayesian statistical frameworks in order to estimate viral evolutionary and population dynamics associated with the outbreak.

Results

Our results revealed an increase in the genetic diversity of human norovirus GII.2 during the recent Asian outbreak and diversification was characterized by at least eight distinct clusters. Bayesian estimation of viral population dynamics revealed a highly fluctuating effective population size, increasing in frequency during the past 15 years.

Conclusion

Despite an increasing viral diversity, we found no evidence of an elevated evolutionary rate or significant selection pressure in human norovirus GII.2, indicating viral evolutionary adaptation was not responsible for the volatility of or spread of the virus during this time.

Assessment of enteric viruses during a hepatitis outbreak in Detroit MI using wastewater surveillance and metagenomic analysis

AIMS

This study investigates enteric viruses in wastewater during an outbreak of acute hepatitis caused by hepatitis A virus (HAV) in a large metropolitan area. Emphasis is given to caliciviruses and HAV.

METHODS AND RESULTS

Metagenomic analysis was performed to characterize enteric viruses excreted by the population of Detroit MI, during a hepatitis A outbreak that occurred in 2017 and 2018. Additionally, HAV, norovirus GII, and sapovirus were quantified, using qPCR, in 54 untreated wastewater samples collected over the course of 4 months. Correlation analysis was performed to identify associations between the number of disease cases and HAV concentrations in wastewater. HAV obtained the highest relative abundance among other enteric viruses detected in wastewater metagenomes. Metagenomic analysis also detected several other enteric viruses including astrovirus, enterovirus and hepatitis E virus. Average sapovirus concentrations of 1·36 × 10⁶  gc l^-1 were significantly greater than norovirus GII concentrations (2·94 × 10⁴  gc l^-1 ). Additionally, norovirus GI and GII along with sapovirus GI.1 were detected using metagenomics. HAV loads in wastewater were significantly correlated with the number of disease cases reported 1 week after wastewater sampling.

CONCLUSIONS

Surveying untreated wastewater is a promising method for detecting early signs of hepatitis A outbreaks and for routine environmental monitoring of enteric viruses circulating in the environment.

SIGNIFICANCE AND IMPACT OF THE STUDY

Authors demonstrate the usefulness of metagenomics for genogrouping and enteric viral surveillance.

Inactivation of norovirus by atmospheric pressure plasma jet on salmon sashimi

This study investigated atmospheric pressure plasma (APP) jet, an emerging novel non-thermal technology, for the inactivation of human norovirus (NoV) on salmon sashimi. The influences of the non-thermal plasma on quality attributes of sashimi were also evaluated. Air, O₂, and N₂ (15 L/min) were used to produce the plasma jets. N₂ plasma treatment for 12 min reduced NoV viral load (VL) (initial inoculums of 2.7 × 10⁴ copies/g) by 2.17 × 10⁴ copies/g, while air-based or O₂-based plasma treatment for 9-12 min could reduce the VL to undetectable levels (below 100 copies/g). Under the same operating condition, the air-based or O₂-based plasma treatment might increase slightly TBARS values in sashimi, yet the values (far below 1.0 mg MDA/kg) were within acceptable level for sashimi made with salmon fishes. The APP jets (APPJ) treatments could also retain the pH of sashimi at normal levels (6.29 ~ 6.02) to maintain the quality of salmon sashimi, the color quality of which was not affected evidently. The plasma-induced hardness and springiness changes in salmon sashimi were substantially low. These results suggested APPJ could be implemented as technology for inactivation of food-borne viruses and exhibited a high potential for application in fish sashimi processing, retaining product quality as well.

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.