Removal and transfer of viruses on food contact surfaces by cleaning cloths

On-The-Spot Sampling and Detection of Viral Particles on Solid Surfaces Using a Sponge Virus Sensor Incorporated with Finger-Press Fluid Release

This paper presents a sponge-based electrochemical sensor for rapid, on-site collection and analysis of infectious viruses on solid surfaces. The device utilizes a conducting porous sponge modified with graphene, graphene oxide, and specific antibodies. The sponge serves as a hydrophilic porous electrode capable of liquid collection and electrochemical measurements. The device operation involves spraying an aqueous solution on a target surface, swiping the misted surface using the sponge, discharging an electrolyte solution with a simple finger press, and performing in situ incubation and electrochemical measurements. By leveraging the water-absorbing ability of the biofunctionalized conducting sponge, the sensor can effectively collect and quantify virus particles from the surface. The portability of the device is enhanced by introducing a push-release feature that dispenses the liquid electrolyte from a miniature reservoir onto the sensor surface. This reservoir has sharp edges to rupture a liquid sealing film with a finger press. The ability of the device to sample and quantify viral particles is demonstrated by using influenza A virus as the model. The sensor provided a calculated limit of detection of 0.4 TCID50/mL for H1N1 virus, along with a practical concentration range from 1-106 TCID50/mL. Additionally, it achieves a 15% collection efficiency from single-run swiping on a tabletop surface. This versatile device allows for convenient on-site virus detection within minutes, eliminating the need for sample pretreatment and simplifying the entire sample collecting and measuring process. This device presents significant potential for rapid virus detection on solid surfaces.

Surface Inactivation of a SARS-CoV-2 Surrogate with Hypochlorous Acid is Impacted by Surface Type, Contact Time, Inoculum Matrix, and Concentration

Indirect contact with contaminated surfaces is a potential transmission route for COVID-19. Therefore, it is necessary to investigate convenient and inexpensive surface sanitization methods, such as HOCl, against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The SARS-CoV-2 surrogate, Phi6 (~ 7 log PFU/mL), was prepared in artificial saliva and tripartite matrices, spot inoculated on coupons of either stainless steel or vinyl, and allowed to dry. The coupons were sprayed with either 500 ppm or 1000 ppm HOCl, and remained on the surface for 0 s (control), 5 s, 30 s, or 60 s. Samples were enumerated via the double agar overlay assay. Statistical analysis was completed in R using a generalized linear model with Quasipoisson error approximations. Time, concentration, surface type, and inoculum matrix were all significant contributors to log reduction at P = 0.05. Significant three-way interactions were observed for 1000 ppm, vinyl, and 60 s (P = 0.03) and 1000 ppm, tripartite, and 60 s (P = 0.0121). A significant two-way interaction between vinyl and 60 s was also observed (P = 0.0168). Overall, increased HOCl concentration and exposure time led to increased Phi6 reduction. Notably, the highest estimated mean log reduction was 3.31 (95% CI 3.14, 3.49) for stainless steel at 60 s and 1000 ppm HOCl in artificial saliva, indicating that this method of sanitization may not adequately reduce enveloped viruses to below infective thresholds.

Hazardous chemical elements in cleaning cloths, a potential source of microfibres

Although potentially hazardous chemical elements (e.g., Cu, Cr, Pb, Sb, Ti, Zn) have been studied in clothing textiles, their presence in cleaning textiles is unknown. In this study, 48 cleaning cloth products (consisting of 81 individual samples) purchased in Europe, and consisting of synthetic (petroleum-based), semi-synthetic or natural fibres or combinations of these different types, have been analysed for 16 chemical elements by X-ray fluorescence (XRF) spectrometry. Titanium was detected in most cases (median and maximum concentrations ~3700 and 12,400 mg kg^-1, respectively) and Raman microspectroscopy revealed that TiO₂ was present as anatase. Barium, Br, Cr, Cu, Fe and Zn were frequently detected over a range of concentrations, reflecting the presence of various additives, and Sb was present at concentrations up to about 200 mg kg^-1 in samples containing polyester as catalytic residue from the polymerisation process. Lead was detected as a contaminant in four samples and at concentrations below 10 mg kg^-1. Overall, the range of the chemical element profiles and concentrations was similar to those for clothing materials published in the literature, suggesting that broadly the same additives, materials and processes are employed to manufacture cloths and clothing textiles. The mechanisms by which potentially hazardous chemical elements are released into the environment with microfibres or mobilised into soluble or nano-particulate forms remain to be explored.

The Efficacy of Commercial Surface Sanitizers against Norovirus on Formica Surfaces with and without Inclusion of a Wiping Step

Commonly used surface sanitizers often lack activity against human noroviruses (hNoVs). The impact of inactivation versus removal when these products are applied via wiping is poorly characterized. The purpose of this work was to assess the anti-hNoV efficacy of various surface sanitizer chemistries, as applied to a laminate material commonly used for restaurant tabletops, using standard surface assays (ASTM E1053-11) and a newly developed wiping protocol. Four commercially available products with different active ingredient(s) (i.e., ethanol [EtOH], acid + anionic surfactant [AAS], quaternary ammonium compound [QAC], and sodium hypochlorite [NaOCl]) and a water control were evaluated against hNoV GII.4 Sydney, hNoV GI.6, and the cultivable surrogate Tulane virus (TuV). Virus concentration was evaluated using RNase-reverse transcriptase (RT)-quantitative PCR (qPCR) (hNoV) and infectivity assay (TuV). Only the EtOH-based product significantly reduced virus concentration (>3.5 log10 reduction [LR]) by surface assay, with all other products producing ≤0.5 LR. The inclusion of a wiping step enhanced the efficacy of all products, producing complete virus elimination for the EtOH-based product and 1.6 to 3.8 LR for the other chemistries. For hNoVs, no detectable residual virus could be recovered from paper towels used to wipe the EtOH-based product, while high concentrations of virus could be recovered from the used paper towel and the wiped coupon (1.5 to 2.5 log10 lower genome equivalent copies [GEC] compared to control) for the QAC- and AAS-based products and for water. These results illustrate the variability in anti-hNoV activity of representative surface sanitizers and highlights the value of wiping, the efficacy of which appears to be driven by a combination of virus inactivation and removal. IMPORTANCE Human noroviruses (hNoVs) are the leading cause of acute gastroenteritis and food-borne disease worldwide. Noroviruses are difficult to inactivate, being recalcitrant to sanitizers and disinfectants commonly used by the retail food sector. This comparative study demonstrates the variability in anti-hNoV activity of representative surface sanitizers, even those allowed to make label claims based on the cultivable surrogate, feline calicivirus (FCV). It also highlights the importance of wiping in the process of sanitization, which significantly improves product efficacy through the action of physical removal of surface microbes. There is a need for more and better product formulations with demonstrated efficacy against hNoVs, which will likely necessitate the use of alternative cultivable surrogates, such as Tulane virus (TuV). These findings help food safety professionals make informed decisions on sanitizing product selection and application methods in order to reduce the risk of hNoV contamination and transmission in their facilities.

Optimizing sample collection methods for detection of respiratory viruses in poultry housing environments

Viral respiratory diseases, such as avian influenza, Newcastle disease, infectious bronchitis, and infectious laryngotracheitis, have considerable negative economic implications for poultry. Ensuring the virus-free status of a premises by environmental sampling after cleaning and disinfection is essential for lifting a quarantine and/or safely restocking the premises following an outbreak. The objectives of this study were to identify optimal sample collection devices and to determine the locations in poultry housing which are best for poultry respiratory virus sample collection. Chickens exposed to infectious bronchitis virus, which was used as a representative virus for enveloped poultry respiratory viruses, were housed in floor-pens in either a curtain-sided wood framed house or a cement block house. Foam swabs, cellulose sponges, polyester swabs, dry cotton gauze and pre-moistened cotton gauze were evaluated for comparative efficiency in recovering viral RNA. Cotton gauze pre-moistened with the viral transport media had the highest sensitivity among the devices (wood-framed house: 78% positive, geometric mean titer [GMT] of 2.6 log₁₀ 50% egg infectious doses [EID₅₀ ] equivalents/ml; cement-block houses: 55% positive, GMT of 1.7 log₁₀ EID₅₀ equivalents/ml). Targeting virus deposition sites is also crucial for efficient virus elimination procedures and subsequent testing, therefore 10 locations within the houses were compared for virus detection. In both housing types the highest viral RNA loads were recovered from the top of drinker lines within the pen. Places the chickens could contact directly (e.g., feeder rim) or were contacted by caretaker feet (hallway floor) also yielded higher levels of viral RNA more consistently. These results will facilitate the establishment of efficient environmental sampling procedures for respiratory viruses of poultry. This article is protected by copyright. All rights reserved.

Efficacy of detergent-based cleaning methods against coronavirus MHV-A59 on porous and non-porous surfaces

This study evaluated the efficacy of detergent-based surface cleaning methods against Murine Hepatitis Virus A59 (MHV) as a surrogate coronavirus for SARS-CoV-2. MHV (5% soil load in culture medium or simulated saliva) was inoculated onto four different high-touch materials [stainless steel (SS), Acrylonitrile Butadiene Styrene plastic (ABS), Formica, seat fabric (SF)]. Immediately and 2-hr post-inoculation, coupons were cleaned (damp wipe wiping) with and without pretreatment with detergent solution or 375 ppm hard water. Results identified that physical removal (no pretreatment) removed >2.3 log₁₀ MHV on ABS, SS, and Formica when surfaces were cleaned immediately. Pretreatment with detergent or hard water increased effectiveness over wet wiping 2-hr post-inoculation; pretreatment with detergent significantly increased (p ≤ 0.05) removal of MHV in simulated saliva, but not in culture media, over hard water pretreatment (Formica and ABS). Detergent and hard water cleaning methods were ineffective on SF under all conditions. Overall, efficacy of cleaning methods against coronaviruses are material- and matrix-dependent; pre-wetting surfaces with detergent solutions increased efficacy against coronavirus suspended in simulated saliva. This study provides data highlighting the importance of incorporating a pre-wetting step prior to detergent cleaning and can inform cleaning strategies to reducing coronavirus surface transmission.

Efficient capturing and sensitive detection of hepatitis A virus from solid foods (green onion, strawberry, and mussel) using protamine-coated iron oxide (Fe3O4) magnetic nanoparticles and real-time RT-PCR

Hepatitis A virus (HAV) continues to be a public health concern and has caused large foodborne outbreaks and economic losses worldwide. Rapid detection of HAV in foods can help to confirm the source of outbreaks in a timely manner and prevent more people getting infected. In order to efficiently detect HAV at low levels of contamination in foods, rapid and easy-to-use techniques are required to separate and concentrate viral particles to a small volume. In the current study, HAV particles were eluted from green onion, strawberry, and mussel using glycine buffer (0.05 M glycine, 0.14 M NaCl, 0.2% (v/v) Tween 20, pH 9.0) and suspended viral particles were captured using protamine-coated magnetic nanoparticles (PMNPs). This process caused a selective concentration of the viral particles, which could be followed by quantitative real-time RT-PCR analysis. Results showed that pH, NaCl concentration, and PMNP amount used for the capturing had significant effects on the recovery efficiency of HAV (P < 0.05). The highest recovery rate was obtained at pH 9.0, 0.14 M NaCl, and 50 μL of PMNPs. The optimized PMNP capturing method enabled the rapid capture and concentration of HAV. A sensitive real-time RT-PCR test was developed with detection limits of 8.3 × 10⁰ PFU/15 g, 8.3 × 10¹ PFU/50 g, and 8.3 × 10⁰ PFU/5 g of HAV in green onion, strawberry, and mussel, respectively. In conclusion, the PMNP method is rapid and convenient in capturing HAV from complex solid food samples and can generate concentrated HAV sample solutions suitable for high-sensitivity real time RT-PCR detection of the virus.

Reduction of Norovirus Surrogates Alone and in Association with Bacteria on Leaf Lettuce and Tomatoes During Application of Aqueous Ozone

Retail foodservice establishments (FSE) frequently utilize washes with sanitizing agents during fresh produce preparation. This study evaluated the efficacy of ozonated water on the inactivation of viruses, bacteria, and viruses in association with bacteria on produce surfaces. Boston bibb lettuce (BB) and cherry tomatoes were spot inoculated with viruses (murine norovirus (MNV) and MS2 bacteriophage), bacteria (Enterobacter cloacae and Bacillus cereus), or MNV associated with E. cloacae or B. cereus. Following inoculation, produce was held at 4 °C for 90 min (virus, virus + bacteria) or 24 h (virus, bacteria) prior to treatment. A batch wash ozone sanitation system (BWOSS) was prepared with ice (3-5 °C) and 0.5 ppm initial ozone concentration or no ozone. Produce samples were treated for 40 min with an ozonated water (0.86-0.99 ppm) or water-only wash with samples taken every 10 min. Samples were processed for microbial recovery, and plaque forming units (PFU) and colony forming units remaining on the produce were determined. Although microbial reductions of 99 to 99.99% were achieved during ozone treatments, few statistically significant differences (P > 0.1) were detected when comparing the ozonated water to water-only wash. Notably, a significant difference (P = 0.009) in log reduction of MNV + bacteria and MNV alone on BB was observed after 40 min ozonated water wash. Specifically, MNV with B. cereus achieved a 1-log greater reduction (2.60 log PFU/ml) compared to MNV alone (1.63 log PFU/ml). Overall, washing produce in ozonated water did not significantly increase microbial inactivation compared to water alone under the conditions presented here. Variables impacting ozone wash effectiveness should be considered when implementing produce wash sanitation systems within FSE.

Inactivation of hepatitis A virus and murine norovirus on surfaces of plastic, steel and raspberries using steam-ultrasound treatment

The leading causes of foodborne viral disease outbreaks are human norovirus and hepatitis A virus (HAV). Their environmental persistence enables contamination of kitchen surfaces and crops often consumed raw, such as berries. Many decontamination procedures are inefficient and unsuitable for surfaces of industrial kitchen environments and soft fruits. In this study, we investigated the efficiency of a novel surface decontamination technology, combining steam and ultrasound (steam-ultrasound). Plastic, steel or raspberry surfaces were spiked with the norovirus surrogate, murine norovirus (MNV), and HAV, and steam-ultrasound treated at 85, 90 and 95 °C for 0-5 s. Post treatment viruses were titrated for survival by plaque assay and for genome stability by real-time quantitative PCR (RT-qPCR) of nucleic acid extracts. Survival of viruses were estimated in a log-linear model and the treatment time requirements for each decimal reduction (D value) in viral survival were calculated. The estimated D values of MNV or HAV were 0.4-0.2 or 1.1-0.8 s on plastic, 0.9-0.7 or 1.4-0.8 s on steel and 1.6-1.7 or 3.2-4.7 s on raspberries. No clear trend of genome reduction was observed with tested treatment parameters. Raspberries treated up to 4 s retained its natural texture and visual appeal similar to untreated controls whilst monitored for 7 days. In conclusion, steam-ultrasound treatment can within seconds reduce the titre of foodborne viruses on surfaces of plastic, steel and raspberries. This may particularly benefit industrial scale production of soft fruits for raw consumption and for swift non-hazardous decontamination of industrial kitchen surfaces.

Characterization of Polyurethane Foam Environmental Monitoring Tools for the Recovery and Release of Viruses

The U.S. FDA Food Safety Modernization Act Preventive Controls for Human Food Rule emphasizes the importance of an effective environmental monitoring (EM) program. This study aims to characterize polyurethane foam (PUF) EM tools-currently used in the food industry for the recovery of bacteria from food contact surfaces-for their efficacy in the release and recovery of human enteric viruses. Two viruses (human norovirus [hNoV] and Tulane virus [TV]) were compared at varying inoculum levels, with two EM tools (PUF swab and sponge), two delayed processing times (24 h and 72 h), and one surface type (stainless steel [SS]). Specifically, the objectives were to (1) determine the ability of PUF devices to release viruses for detection and (2) assess the ability of PUF devices to recover viruses from SS surfaces. For TV release from the sponge, there was a significant difference (p = 0.0064) when compared across inoculum level (10⁵ plaque forming unit [PFU]/sponge vs. 10² PFU/sponge). Release of hNoV at a single inoculum level by PUF sponge and swab was compared resulting in a significant difference (p < 0.0001). Data on recovery of TV from SS surfaces using both the sponge and swab indicate significant differences depending on the inoculum level. Recovery of hNoV from SS surfaces differed significantly (p = 0.0030) between the sponge and swab devices. Overall, the study provides a detailed characterization of two commercially available, PUF-based EM tools, and the differences identified in this study can be used to improve the efficacy of EM tools.

Efficacy of the SuperTowel®: An Alternative Hand-washing Product for Humanitarian Emergencies

Handwashing with soap reduces the transmission of diarrheal pathogens, but access to hand-washing facilities, water, and soap in humanitarian emergencies is limited. The SuperTowel^® (ST) is a fabric treated with permanent antimicrobial bonding and has been designed as a soap alternative in emergency situations. The aim of this study was to test the efficacy of the ST as a hand-cleaning product. Two sets of laboratory tests, with 16 volunteers in each, were conducted to test the efficacy of different prototypes of the ST. Volunteers pre-contaminated their hands with nonpathogenic Escherichia coli. Comparisons were made between hand cleaning with the ST and handwashing with the reference soap, using a crossover design. Participants also completed a questionnaire about product perceptions. Three of the prototypes of the ST were more efficacious at removing E. coli from pre-contaminated hands than handwashing with soap (mean log₁₀ reduction of 4.11 ± 0.47 for ST1, 3.84 ± 0.61 for ST2, and 3.71 ± 0.67 for ST3 versus 3.01 ± 0.63 for soap [P < 0.001, P = 0.002, and P = 0.005, respectively]). The ST prototypes used less water than handwashing with soap, were well accepted, and were considered preferable in communal settings. The ST has the potential to be a suitable complementary hand-cleaning product for humanitarian emergencies.

Guidelines for Frontline Health Care Staff Safety for COVID-19

This document establishes safety guidelines for physicians, nurses, and allied health care and facility staff who may be exposed to patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in a health care facility. SARS-CoV-2 infection is highly contagious and places health care workers at risk for infection resulting in coronavirus disease (COVID-19). Physicians, nurses, and allied health care and facility staff in all frontline environments must be provided and utilize necessary personal protective equipment (PPE). It is important that health care staff adopt a universal set of guidelines in which to conduct themselves in order to minimize infection with the SARS-CoV-2 contagion. The establishment of these guidelines is necessary in this viral pandemic since such directives can create a standard of safety that is universally accepted. These guidelines establish a framework to provide consistency among health care facilities and staff from the time the staff member arrives at the health care facility until they return home. These guidelines provide a practical description of the minimum necessary protection for physicians, nurses, and allied health care and facility staff against SARS-CoV-2 infection.

Don't Shut the Stable Door after the Phage Has Bolted-The Importance of Bacteriophage Inactivation in Food Environments

In recent years, a new potential measure against foodborne pathogenic bacteria was rediscovered-bacteriophages. However, despite all their advantages, in connection to their widespread application in the food industry, negative consequences such as an uncontrolled phage spread as well as a development of phage resistant bacteria can occur. These problems are mostly a result of long-term persistence of phages in the food production environment. As this topic has been neglected so far, this article reviews the current knowledge regarding the effectiveness of disinfectant strategies for phage inactivation and removal. For this purpose, the main commercial phage products, as well as their application fields are first discussed in terms of applicable inactivation strategies and legal regulations. Secondly, an overview of the effectiveness of disinfectants for bacteriophage inactivation in general and commercial phages in particular is given. Finally, this review outlines a possible strategy for users of commercial phage products in order to improve the effectiveness of phage inactivation and removal after application.

Could the Supertowel be used as an alternative hand cleaning product for emergencies? An acceptability and feasibility study in a refugee camp in Ethiopia

BACKGROUND

Diarrhoeal diseases are a major contributor to morbidity and mortality in humanitarian crises. Handwashing with soap may reduce diarrhoea by up to 47%, however, the circumstances associated with displacement make it challenging for crisis-affected populations to be able to wash their hands with soap. The Supertowel is an alternative hand-cleaning product, proven to be as efficacious as handwashing with soap. The Supertowel is a micro-fibre towel with an anti-microbial treatment. When dipped in water it is capable of removing and killing pathogens from hands. This study aims to assess whether the Supertowel could be an acceptable and feasible product for crisis-affected populations.

METHODS

The study took place in an Eritrean refugee camp located in Tigray state in Ethiopia. We used a mix of qualitative methods to understand use and acceptability, including baseline observations (n = 13), behaviour trials involving interviews at three time points (n = 19) and focus group discussions (n = 3). We thematically analysed data from interviews and discussions.

RESULTS

Participants indicated that the Supertowel was convenient, easy to use and saved them water and money. All households participating in the behaviour trials had at least one Supertowel in use at the end of the trials (follow-up visit two). In discussions participants reported that the Supertowel was more desirable than comparable hand cleaning products. In interviews, trial participants explained that the product enabled them to clean their hands at times when they might not normally bother. The research also identified some issues with the smell of the Supertowel and its intuitive use.

CONCLUSIONS

The Supertowel was found to be an acceptable and useful hand-cleaning product that could complement soap use in crisis contexts. This pilot study also identified areas of future research including the need to compare different distribution models for the Supertowel (distribution in hygiene kits compared to distribution with an accompanying communication package) and to evaluate its use at scale over a longer time period.

The survival and inactivation of enteric viruses on soft surfaces: A systematic review of the literature

BACKGROUND

Worldwide, enteric viruses are the main cause of acute gastroenteritis. In humans, these viruses spread via person-to-person contact, food, water, and/or the environment. Their survival and inactivation on hard surfaces have been extensively studied; however, nonlaunderable soft surfaces, such as upholstery and carpet, have received little attention. The aim of this systematic review was to determine factors that influence the survival and inactivation of enteric viruses on nonlaunderable soft surfaces.

METHODS

EBSCO and Web of Science were searched for experimental studies published between 1965 and 2015 using Preferred Reporting Items for Systematic Reviews and Meta-Analyses methods. Titles and abstracts were screened using 3 eligibility criteria. The quality of all study methods was also assessed.

RESULTS

Our search yielded 12 articles. Viruses survived between 0 hours and 140 days depending on surface and environment conditions. Virus survival was influenced by temperature, relative humidity, organic content, and deposition method. A variety of chemistries were tested across studies and were shown to have a varied effect on enteric viruses. Chlorine, glutaraldehyde, vaporous ozone, and hydrogen peroxide were the most efficacious against enteric viruses (> 3-log reduction).

CONCLUSIONS

Environmental factors, such as temperature and relative humidity, can influence survival of enteric viruses on nonlaunderable soft surfaces. The efficacy of liquid and vaporous chemistries are associated with surface and virus type.

Evaluation of a Recirculating Dipper Well Combined with Ozone Sanitizer for Control of Foodborne Pathogens in Food Service Operations

In the retail food service industry, small countertop sinks, or dipper wells, are utilized to rinse and store serving utensils between uses. These dipper wells are designed to operate under a constant flow of water, which serves both to prevent the accumulation of microorganisms and to aid in the cleanliness of the dipper well itself. Here, a recirculating dipper well ozone sanitation system (DWOSS) was evaluated for the control and inactivation of Escherichia coli , Listeria innocua , PRD1 bacteriophage, and Staphylococcus aureus present on a stainless steel disher. In a low ozone (O₃) demand medium, the DWOSS achieved over a 5-log reduction for E. coli , L. innocua , and PRD1 at 30 s when exposed to 0.45 to 0.55 ppm of residual O₃. A greater than 5-log total CFU reduction was achieved for S. aureus at a 600-s exposure time and 0.50 ppm of residual O₃. When evaluated in the presence of high O₃ demand medium (10% skim milk), the DWOSS performed significantly better (P < 0.05) for all microbe-exposure time combinations compared with a conventional dipper well with respect to the reduction of microbes on the stainless steel disher. For example, at 30 s, the DWOSS achieved 4.37, 2.48, 1.38, and 1.31 greater log (CFU or PFU) reduction of E. coli , L. innocua , PRD1, and S. aureus , respectively, than a conventional dipper well. In addition, the DWOSS was evaluated under two neglect scenarios to determine its ability to control microbes in 10% skim milk medium on the stainless steel disher and within the dipper well basin itself over an extended period of use (2 h of use per day over 5 days). Considering the efficacy of the DWOSS unit against the microbes evaluated here, the integration of ozone into a dipper well could be a potential critical control point to reduce the incidence of microbial contamination during retail food service. To our knowledge, a dipper well with a cleaning-in-place sanitizing system is not currently available for use in the food service industry; and, thus, this is the first study to evaluate the efficacy of a cleaning-in-place dipper well.

Noroviruses on surfaces: detection, persistence, disinfection and role in environmental transmission

Human noroviruses (HuNoVs), the most common cause of infectious nonbacterial gastroenteritis and the cause of numerous foodborne and hospital outbreaks, are easily transmitted from person-to-person. HuNoVs may persist on surfaces for long periods of time and may be transferred via hands, foods, fomites and air. In this review, studies on methods for detecting HuNoVs on environmental surfaces, such as swabbing, are presented. The review also focuses on recent studies on the efficiency of disinfectants for inactivating HuNoV or its surrogates, such as murine norovirus, on environmental surfaces and hands. Although HuNoV is probably more resistant than MuNoV, this study data adds to the understanding of HuNoV transmission routes and selection of tools for the prevention of HuNoV gastroenteritis outbreaks.

Recovery and Disinfection of Two Human Norovirus Surrogates, Feline Calicivirus and Murine Norovirus, from Hard Nonporous and Soft Porous Surfaces

Human norovirus is a leading cause of foodborne disease and can be transmitted through many routes, including environmental exposure to fomites. In this study, both the recovery and inactivation of two human norovirus surrogates, feline calicivirus (FCV) and murine norovirus (MNV), on hard nonporous surfaces (glass) and soft porous surfaces (polyester and cotton) were evaluated by both plaque assay and reverse transcription quantitative PCR method. Two disinfectants, sodium hypochlorite (8.25%) and accelerated hydrogen peroxide (AHP, at 4.25%) were evaluated for disinfection efficacy. Five coupons per surface type were used to evaluate the recovery of FCV and MNV by sonication and stomaching and the disinfection of each surface type by using 5 ml of disinfectant for a contact time of 5 min. FCV at an initial titer of ca. 7 log PFU/ml was recovered from glass, cotton, and polyester at 6.2, 5.4, and 3.8 log PFU/ml, respectively, compared with 5.5, 5.2, and 4.1 log PFU/ml, respectively, for MNV with an initial titer of ca. 6 log PFU/ml. The use of sodium hypochlorite (5,000 ppm) was able to inactivate both FCV and MNV (3.1 to 5.5 log PFU/ml) below the limit of detection on all three surface types. AHP (2,656 ppm) inactivated FCV (3.1 to 5.5 log PFU/ml) below the limit of detection for all three surface types but achieved minimal inactivation of MNV (0.17 to 1.37 log PFU/ml). Reduction of viral RNA by sodium hypochlorite corresponded to 2.72 to 4.06 log reduction for FCV and 2.07 to 3.04 log reduction for MNV on all three surface types. Reduction of viral RNA by AHP corresponded to 1.89 to 3.4 log reduction for FCV and 0.54 to 0.85 log reduction for MNV. Our results clearly indicate that both virus and surface types significantly influence recovery efficiency and disinfection efficacy. Based on the performance of our proposed testing method, an improvement in virus recovery will be needed to effectively validate virus disinfection of soft porous surfaces.

Norovirus cross-contamination during preparation of fresh produce

Infection with human norovirus (HuNoV) is considered a common cause of foodborne illness worldwide. Foodborne HuNoV outbreaks may result from consumption of food contaminated by an infected food handler in the foodservice environment, in which bare-hand contact, lack of hand washing, and inadequate cleaning and disinfection are common contributing factors. The goal of this study was to examine cross-contamination of a HuNoV surrogate, murine norovirus (MNV-1), during common procedures used in preparing fresh produce in a food service setting, including turning water spigots, handling and chopping Romaine lettuce, and washing hands. MNV-1 transfer % was log-transformed to achieve a normal distribution of the data and enable appropriate statistical analyses to be performed. MNV-1 transfer coefficients varied by surface type, and a greater affinity for human hands and chopped lettuce was observed. For example, greater transfer was observed from a contaminated stainless steel spigot to a clean hand (24% or 1.4-log transfer %) compared to transfer from hand to spigot (0.6% or -0.2-log transfer %). During the chopping of Romaine lettuce, MNV-1 was transferred from either a contaminated cutting board (25% or 1.4-log transfer %) or knife (~100% or 2.0-log transfer %) to lettuce at a significantly greater rate (p>0.05) than from contaminated lettuce to the board (2.1% or 0.3-log transfer %) and knife (1.2% or 0.06-log transfer %). No significant difference (p>0.05) in MNV-1 transfer coefficients was observed between bare hands and Romaine lettuce during handling. For handwashing trials, only one hand was inoculated with MNV-1 prior to washing. The handwashing methods included rubbing hands under tap water for at least 5s (average 2.8-log reduction) or washing hands for at least 20s with liquid soap (average 2.9-log reduction) or foaming soap (average 3.0-log reduction), but no statistical difference between these reductions was achieved (p>0.05). Despite the reductions of MNV-1 observed, residual virions were detected on both hands after washing in every replicate trial. This observation reveals that virions are transferred from one hand to the other during washing with and without soap. Each transfer scenario was repeated at least 9 times, and the data gathered indicate that MNV-1 transfers readily between common surfaces during food preparation. These data are important for the development of quantitative risk analyses, and will assist in the development of appropriate intervention strategies for enteric viruses in food preparation.

Controlling hospital-acquired infection: focus on the role of the environment and new technologies for decontamination

There is increasing interest in the role of cleaning for managing hospital-acquired infections (HAI). Pathogens such as vancomycin-resistant enterococci (VRE), methicillin-resistant Staphylococcus aureus (MRSA), multiresistant Gram-negative bacilli, norovirus, and Clostridium difficile persist in the health care environment for days. Both detergent- and disinfectant-based cleaning can help control these pathogens, although difficulties with measuring cleanliness have compromised the quality of published evidence. Traditional cleaning methods are notoriously inefficient for decontamination, and new approaches have been proposed, including disinfectants, steam, automated dispersal systems, and antimicrobial surfaces. These methods are difficult to evaluate for cost-effectiveness because environmental data are not usually modeled against patient outcome. Recent studies have reported the value of physically removing soil using detergent, compared with more expensive (and toxic) disinfectants. Simple cleaning methods should be evaluated against nonmanual disinfection using standardized sampling and surveillance. Given worldwide concern over escalating antimicrobial resistance, it is clear that more studies on health care decontamination are required. Cleaning schedules should be adapted to reflect clinical risk, location, type of site, and hand touch frequency and should be evaluated for cost versus benefit for both routine and outbreak situations. Forthcoming evidence on the role of antimicrobial surfaces could supplement infection prevention strategies for health care environments, including those targeting multidrug-resistant pathogens.

Wipes coated with a singlet-oxygen-producing photosensitizer are effective against human influenza virus but not against norovirus

Transmission of enteric and respiratory viruses, including human norovirus (hNoV) and human influenza virus, may involve surfaces. In food preparation and health care settings, surfaces are cleaned with wipes; however, wiping may not efficiently reduce contamination or may even spread viruses, increasing a potential public health risk. The virucidal properties of wipes with a singlet-oxygen-generating immobilized photosensitizer (IPS) coating were compared to those of similar but uncoated wipes (non-IPS) and of commonly used viscose wipes. Wipes were spiked with hNoV GI.4 and GII.4, murine norovirus 1 (MNV-1), human adenovirus type 5 (hAdV-5), and influenza virus H1N1 to study viral persistence. We also determined residual and transferred virus proportions on steel carriers after successively wiping a contaminated and an uncontaminated steel carrier. On IPS wipes only, influenza viruses were promptly inactivated with a 5-log10 reduction. D values of infectious MNV-1 and hAdV-5 were 8.7 and 7.0 h on IPS wipes, 11.6 and 9.3 h on non-IPS wipes, and 10.2 and 8.2 h on viscose wipes, respectively. Independently of the type of wipe, dry cleaning removed, or drastically reduced, initial spot contamination of hNoV on surfaces. All wipes transferred hNoV to an uncontaminated carrier; however, the risk of continued transmission by reuse of wipes after 6 and 24 h was limited for all viruses. We conclude that cleaning wet spots with dry wipes efficiently reduced spot contamination on surfaces but that cross-contamination with noroviruses by wiping may result in an increased public health risk at high initial virus loads. For influenza virus, IPS wipes present an efficient one-step procedure for cleaning and disinfecting contaminated surfaces.

Inactivation of norovirus on dry copper alloy surfaces

Noroviruses (family Caliciviridae) are the primary cause of viral gastroenteritis worldwide. The virus is highly infectious and touching contaminated surfaces can contribute to infection spread. Although the virus was identified over 40 years ago the lack of methods to assess infectivity has hampered the study of the human pathogen. Recently the murine virus, MNV-1, has successfully been used as a close surrogate. Copper alloys have previously been shown to be effective antimicrobial surfaces against a range of bacteria and fungi. We now report rapid inactivation of murine norovirus on alloys, containing over 60% copper, at room temperature but no reduction of infectivity on stainless steel dry surfaces in simulated wet fomite and dry touch contamination. The rate of inactivation was initially very rapid and proportional to copper content of alloy tested. Viral inactivation was not as rapid on brass as previously observed for bacteria but copper-nickel alloy was very effective. The use of chelators and quenchers of reactive oxygen species (ROS) determined that Cu(II) and especially Cu(I) ions are still the primary effectors of toxicity but quenching superoxide and hydroxyl radicals did not confer protection. This suggests Fenton generation of ROS is not important for the inactivation mechanism. One of the targets of copper toxicity was the viral genome and a reduced copy number of the gene for a viral encoded protein, VPg (viral-protein-genome-linked), which is essential for infectivity, was observed following contact with copper and brass dry surfaces. The use of antimicrobial surfaces containing copper in high risk closed environments such as cruise ships and care facilities could help to reduce the spread of this highly infectious and costly pathogen.

Swabs as a tool for monitoring the presence of norovirus on environmental surfaces in the food industry

Human norovirus (HuNoV), which causes gastroenteritis, can be transmitted to food and food contact surfaces via viruscontaminated hands. To investigate this transmission in food processing environments, we developed a swabbing protocol for environmental samples, evaluated the stability of HuNoV in the swabs, and applied the method in the food industry. Swabs made of polyester, flocked nylon, cotton wool, and microfiber were moistened in either phosphate-buffered saline (PBS) or glycine buffer (pH 9.5) and used to swab four surfaces (latex, plastic, stainless steel, and cucumber) inoculated with HuNoV. HuNoV was eluted with either PBS or glycine buffer and detected with quantitative reverse transcription PCR. HuNoV recoveries were generally higher with an inoculation dose of 100 PCR units than 1,000 PCR units. The highest recoveries were obtained when surfaces were swabbed with microfiber cloth moistened in and eluted with glycine buffer after a HuNoV inoculation dose of 100 PCR units: 66% ± 18% on latex, 89% ±2% on plastic, and 79% ±10% on stainless steel. The highest recovery for cucumber, 45% ±5%, was obtained when swabbing the surface with microfiber cloth and PBS. The stability of HuNoV was tested in microfiber cloths moistened in PBS or glycine buffer. HuNoV RNA was detected from swabs after 3 days at 4 and 22°C, although the RNA levels decreased more rapidly in swabs moistened with glycine buffer than in those moistened with PBS at 22°C. In the field study, 172 microfiber and 45 cotton wool swab samples were taken from environmental surfaces at three food processing companies. Five (5.6%) of 90 swabs collected in 2010 and 7 (8.5%) of 82 swabs collected in 2012 were positive for HuNoV genogroup II; all positive samples were collected with microfiber swabs. Three positive results were obtained from the production line and nine were obtained from the food workers' break room and restroom areas. Swabbing is a powerful tool for HuNoV RNA detection from environmental surfaces and enables investigation of virus transmission during food processing.

Norovirus transfer between foods and food contact materials

Human infective noroviruses (NoVs) are a worldwide leading cause of foodborne illness and are frequently spread via infected food handlers preparing and manipulating food products such as deli sandwiches. The objective of the current study was to determine the efficiencies whereby NoV could be transferred between surfaces associated with the preparation of manually prepared foods such as deli sandwiches. Nonfood surfaces included gloves and stainless steel discs, and boiled ham, lettuce, and a sandwich bun were the ingredients of the deli sandwich. Both NoV GII.4 and the murine NoV 1 (MNV-1, a cultivable human NoV surrogate) were included in the presented study. Transfer of NoV GII.4 and MNV-1 between surfaces was performed by pressing an inoculated donor surface against an acceptor surface. To evaluate the effect of subsequent contact, donor surfaces were pressed a second time to an identical acceptor surface. Subsequently, NoV GII.4 and MNV-1 were detected using real-time reverse transcription PCR assays and plaque assays, respectively. Transfer of both viruses from gloves to stainless steel was inefficient, and virus transfer from food products to stainless steel occurred with more variability for NoV GII.4 than for MNV-1. Virus transfer from the stainless steel discs to the gloves was substantially more efficient than from the gloves to the stainless steel. NoV GII.4 and MNV-1 transfer from food products to the gloves occurred with varying efficiencies, although this variation was more evident for NoV GII.4. The MNV-1 inoculum was significantly less efficiently transferred to the acceptor surface at the second contact, which was not the case for NoV GII.4. The obtained transfer efficiency data may provide insights into the transfer of NoV during preparation of foods and can be included in risk assessment models describing the transmission of NoVs in this context.

Sanitizer efficacy against murine norovirus, a surrogate for human norovirus, on stainless steel surfaces when using three application methods

Human noroviruses are major etiologic agents of epidemic gastroenteritis. Outbreaks are often accompanied by contamination of environmental surfaces, but since these viruses cannot be routinely propagated in laboratory cultures, their response to surface disinfectants is predicted by using surrogates, such as murine norovirus 1 (MNV-1). This study compared the virucidal efficacies of various liquid treatments (three sanitizer liquids, 5% levulinic acid plus 2% SDS [LEV/SDS], 200 ppm chlorine, and an isopropanol-based quaternary ammonium compound [Alpet D2], and two control liquids, sterile tap water and sterile tap water plus 2% SDS) when delivered to MNV-1-inoculated stainless steel surfaces by conventional hydraulic or air-assisted, induction-charged (AAIC) electrostatic spraying or by wiping with impregnated towelettes. For the spray treatments, LEV/SDS proved effective when applied with hydraulic and AAIC electrostatic spraying, providing virus reductions of 2.71 and 1.66 log PFU/ml, respectively. Alpet D2 provided a 2.23-log PFU/ml reduction with hydraulic spraying, outperforming chlorine (1.16-log PFU/ml reduction). Chlorine and LEV/SDS were equally effective as wipes, reducing the viral load by 7.05 log PFU/ml. Controls reduced the viral load by <1 log with spraying applications and by >3 log PFU/ml with wiping. Results indicated that both sanitizer type and application methods should be carefully considered when choosing a surface disinfectant to best prevent and control environmental contamination by noroviruses.

Bacteriophages in food fermentations: new frontiers in a continuous arms race

Phage contamination represents an important risk to any process requiring bacterial growth, particularly in the biotechnology and food industries. The presence of unwanted phages may lead to manufacturing delays, lower quality product, or, in the worst cases, total production loss. Thus, constant phage monitoring and stringent application of the appropriate control measures are indispensable. In fact, a systematic preventive approach to phage contamination [phage analysis and critical control points (PACCP)] should be put in place. In this review, sources of phage contamination and novel phage detection methods are described, with an emphasis on bacterial viruses that infect lactic acid bacteria used in food fermentations. Recent discoveries related to antiphage systems that are changing our views on phage-host interactions are highlighted. Finally, future directions are also discussed.

Residual viral and bacterial contamination of surfaces after cleaning and disinfection

Environmental surfaces contaminated with pathogens can be sources of indirect transmission, and cleaning and disinfection are common interventions focused on reducing contamination levels. We determined the efficacy of cleaning and disinfection procedures for reducing contamination by noroviruses, rotavirus, poliovirus, parechovirus, adenovirus, influenza virus, Staphylococcus aureus, and Salmonella enterica from artificially contaminated stainless steel surfaces. After a single wipe with water, liquid soap, or 250-ppm free chlorine solution, the numbers of infective viruses and bacteria were reduced by 1 log(10) for poliovirus and close to 4 log(10) for influenza virus. There was no significant difference in residual contamination levels after wiping with water, liquid soap, or 250-ppm chlorine solution. When a single wipe with liquid soap was followed by a second wipe using 250- or 1,000-ppm chlorine, an extra 1- to 3-log(10) reduction was achieved, and except for rotavirus and norovirus genogroup I, no significant additional effect of 1,000 ppm compared to 250 ppm was found. A reduced correlation between reduction in PCR units (PCRU) and reduction in infectious particles suggests that at least part of the reduction achieved in the second step is due to inactivation instead of removal alone. We used data on infectious doses and transfer efficiencies to estimate a target level to which the residual contamination should be reduced and found that a single wipe with liquid soap followed by a wipe with 250-ppm free chlorine solution was sufficient to reduce the residual contamination to below the target level for most of the pathogens tested.