Norovirus and Foodborne Disease: A Review

Near-source wastewater surveillance of SARS-CoV-2, norovirus, influenza virus and RSV across five different sites in the UK

By tracking infectious diseases through sewage, municipal-scale wastewater surveillance has provided early warnings of future COVID-19 hospitalisations, identified biases in diagnostic testing, and is rapidly expanding to a broader array of pathogens. Despite applications in the targeted delivery of local interventions, near-source wastewater surveillance has received less attention and we know little about the near-source time series dynamics of contrasting pathogens. To address this, we conducted wastewater surveillance at five sites for SARS-CoV-2 and two sites for norovirus GI, norovirus GII, influenza A virus, influenza B virus, and human respiratory syncytial virus (RSV A and RSV B). Sites were selected for contrasting functions: an office, charity centre, museum, university, and care home. The key findings are (1) near-source wastewater detections were linked to local events (staff sickness, enhanced cleaning, changing populations); (2) wastewater detections decreased in the order norovirus GII > norovirus GI > SARS-CoV-2 ≈ influenza A ≈ RSV A > influenza B ≈ RSV B; (3) correlation between near-source wastewater data and national surveillance data increases as a function of catchment size and viral prevalence (examples include the SARS-CoV-2 BA.4/BA.5 variant peak at a museum and wastewater tracking the winter norovirus season); (4) strong weekday periodicity in near-source wastewater SARS-CoV-2 detections, with the correlation against COVID-19 case numbers increasing when modelling variable lag times between faecal shedding onset and clinical diagnosis (R2 = 0.45 increases to 0.84-0.86); (5) a log-linear relationship between the frequency of wastewater SARS-CoV-2 detection and log(catchment size⋅viral prevalence) (R2 = 0.6914-0.9066). Finally, we propose two use cases. Firstly, for rare or high-risk pathogens, near-source wastewater sentinel systems provide early warning of outbreaks, achieving high frequency community coverage without behaviour change and at low cost versus diagnostic testing. Secondly, for endemic pathogens, near-source wastewater reveals long-term patterns and trends, the effectiveness of local policies, and community vulnerabilities.

Norovirus detection technologies: From conventional methods to innovative biosensors

The norovirus (NoV), known for its high contagion rate, is the leading cause of acute gastroenteritis. The development of a NoV vaccine is hindered by significant antigenic variation, lack of suitable models, unknown vaccine protection duration, limited human challenge studies, complex performance patterns, and the absence of a reliable in vitro cultivation system, making prevention, early detection, and control the only effective measures to mitigate outbreaks. This review aims to discuss about several norovirus biosensor for point-of-care analysis. Several innovative biosensors have been developed, including techniques such as electrochemical NoV biosensors, colorimetric NoV biosensors, fluorescence NoV biosensors, CRISPR-based NoV biosensors, and other NoV biosensors. These approaches have detected norovirus in biological samples with high sensitivity and specificity. This biosensing technique holds significant promise, not only in improving the speed and accuracy of diagnostic processes but also in strengthening the global response to norovirus infections, thereby underscoring its pivotal role in public health and disease prevention.

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.

Prevention of foodborne viruses and pathogens in fresh produce and root vegetables

Every year, 1 in 10 people suffers from food poisoning, and in recent years, the highest number of foodborne outbreaks has been attributed to roots/underground vegetables and fresh produce. Major pathogens include as Escherichia coli, Salmonella enterica, Listeria monocytogenes, Human Norovirus, Hepatitis A virus and Cyclospora. The primary sources of contamination for agriculture products stem from uncontrolled exposure to soil, water, and animal waste. Contamination can occur in various ways during food cultivation, harvesting, processing, and distribution. Mechanical washing and disinfection are primarily employed as practices to control biological contaminants such as bacteria, viruses, and parasites. Current practices may encounter challenges such as microbial resistance to disinfectants or antibiotics, and the cleaning effectiveness could be compromised due to the internalization of bacteria and viruses into some plants. High-pressure processing, pulse electric fields, and cold plasma are environmentally friendly technologies, albeit with associated costs. Low-temperature sterilization technologies capable of controlling biological contaminants, such as bacteria and viruses, play a crucial role in preventing food safety issues. Compared to conventional cleaning methods, these technologies are effective in controlling microorganisms that are strongly attached to the food surface or internalized due to damage. Periodic surveillance is essential to ensure the overall microbiological safety of fresh produce and root vegetables.

Rapid Virucidal Activity of Japanese Saxifraga Species-Derived Condensed Tannins against SARS-CoV-2, Influenza A Virus, and Human Norovirus Surrogate Viruses

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza A virus (IAV), and norovirus are global threats to human health. The application of effective virucidal agents, which contribute to the inactivation of viruses on hands and environmental surfaces, is important to facilitate robust virus infection control measures. Naturally derived virucidal disinfectants have attracted attention owing to their safety and eco-friendly properties. In this study, we showed that multiple Japanese Saxifraga species-derived fractions demonstrated rapid, potent virucidal activity against the SARS-CoV-2 ancestral strain and multiple variant strains, IAV, and two human norovirus surrogates: feline calicivirus (FCV) and murine norovirus (MNV). Condensed tannins were identified as active chemical constituents that play a central role in the virucidal activities of these fractions. At a concentration of 25 μg/mL, the purified condensed tannin fraction Sst-2R induced significant reductions in the viral titers of the SARS-CoV-2 ancestral strain, IAV, and FCV (reductions of ≥3.13, ≥3.00, and 2.50 log₁₀ 50% tissue culture infective doses [TCID₅₀]/mL, respectively) within 10 s of reaction time. Furthermore, at a concentration of 100 μg/mL, Sst-2R induced a reduction of 1.75 log₁₀ TCID₅₀/mL in the viral titers of MNV within 1 min. Western blotting and transmission electron microscopy analyses revealed that Sst-2R produced structural abnormalities in viral structural proteins and envelopes, resulting in the destruction of viral particles. Furthermore, Saxifraga species-derived fraction-containing cream showed virucidal activity against multiple viruses within 10 min. Our findings indicate that Saxifraga species-derived fractions containing condensed tannins can be used as disinfectants against multiple viruses on hands and environmental surfaces. IMPORTANCE SARS-CoV-2, IAV, and norovirus are highly contagious pathogens. The use of naturally derived components as novel virucidal/antiviral agents is currently attracting attention. We showed that fractions from extracts of Saxifraga species, in the form of a solution as well as a cream, exerted potent, rapid virucidal activities against SARS-CoV-2, IAV, and surrogates of human norovirus. Condensed tannins were found to play a central role in this activity. The in vitro cytotoxicity of the purified condensed tannin fraction at a concentration that exhibited some extent of virucidal activity was lower than that of 70% ethanol or 2,000 ppm sodium hypochlorite solution, which are popular virucidal disinfectants. Our study suggests that Saxifraga species-derived fractions containing condensed tannins can be used on hands and environmental surfaces as safe virucidal agents against multiple viruses.

[Molecular epidemiology and evolution of human noroviruses]

Noroviruses are the most common viral cause of acute gastroenteritis after the introduction of rotavirus vaccines. Norovirus infection can cause severe symptoms in vulnerable populations including young children and the elderly. Thus, it is still a leading cause of death from diarrhea in children in developing countries. Recent advancement of genomics platforms facilitated understanding of the epidemiology of norovirus, while the whole picture of norovirus diversity is still undetermined. Currently, there are no approved vaccines for norovirus, but state-of-the-art norovirus cultivation systems could elucidate the antigenic diversity of this fast-evolving virus. In this review, we will summarize the historical and latest findings of norovirus epidemiology, diversity, and evolution.

A foodborne norovirus outbreak in a nursing home and spread to staff and their household contacts

On 16 March 2018, a nursing home notified a possible acute gastroenteritis outbreak that affected 11 people. Descriptive and case-control studies and analysis of clinical and environmental samples were carried out to determine the characteristics of the outbreak, its aetiology, the transmission mechanism and the causal food. The extent of the outbreak in and outside the nursing home was determined and the staff factors influencing propagation were studied by multivariate analysis. A turkey dinner on March 14 was associated with the outbreak (OR 4.22, 95% CI 1.11-16.01). Norovirus genogroups I and II were identified in stool samples. The attack rates in residents, staff and household contacts of staff were 23.49%, 46.22% and 22.87%, respectively. Care assistants and cleaning staff were the staff most frequently affected. Cohabitation with an affected care assistant was the most important factor in the occurrence of cases in the home (adjusted OR 6.37, 95% CI 1.13-36.02). Our results show that staff in close contact with residents and their household contacts had a higher risk of infection during the norovirus outbreak.

Evaluation of multinomial logistic regression models for predicting causative pathogens of food poisoning cases

In cases of food poisoning, it is important for food sanitation inspectors to determine the causative pathogen as early as possible and take necessary measures to minimize outbreaks. Interviews are usually conducted to obtain epidemiological information to aid in the rapid determination of the cause. However, the current method of determining the causative pathogen has the disadvantage of being reliant upon the experience and knowledge of food sanitation inspectors. Here, we analyzed 529 infectious food poisoning incidents reported in five municipalities in the Kinki region to develop a tool for evaluation using a multinomial logistic regression model, which can predict the causative pathogen based on the patients' epidemiological information. This tool predicts the most probable cause of the incident by generating a list of pathogens with the highest probability. As a result of leave-one-out cross validation, the agreement ratio with the actual pathogen was 86.4%, and this ratio increased to 97.5% when the agreement was judged by including the true pathogen within the top three pathogens with the highest probability. In cases where the difference of probability between the first and second candidate pathogen was ≥50%, the agreement ratio increased to 94.2%. Using this tool, it is possible to accurately estimate the causative pathogen at an early stage based on patient information, and this will further help narrow the target of investigations to identify causative agent, thereby leading to a prompt identification, which can prevent the spread of food poisoning.

Impedance Analysis of Colloidal Gold Nanoparticles in Chromatography Paper for Quantitation of an Immunochromatographic Assay

A detection method of gold nanoparticles in chromatography paper has been developed for a simple, cost-effective and reliable quantitation of immunochromatographic strip test. The time courses of the solution resistance in chromatography paper with the gold nanoparticles solution are electrochemically measured by chrono-impedimetry. The dependence of the solution resistance on the concentration of gold nanoparticles has been successfully observed. The main factor to increase the solution resistance may be obstruction of the ion transport due to the presence of gold nanoparticles. The existence of gold nanoparticles with 1.92 × 10(9) particles/mL in an indistinctly-colored chromatography paper is also identified by a solution resistance measurement. This indicates that the solution resistance assay has the potential to lower the detection limit of the conventional qualitative assay.