Efficacy of chemical disinfectant compounds against human norovirus

Antimicrobial Activity of Hydrogen Peroxide for Application in Food Safety and COVID-19 Mitigation: An Updated Review

Hydrogen peroxide (H2O2) is a well-known agent with a broad-spectrum antimicrobial activity against pathogenic bacteria, fungi, and viruses. It is a colorless liquid and commercially available in aqueous solution over a wide concentration range. It has been extensively used in the food industry by virtue of its strong oxidizing property and its ability to cause cellular oxidative damage in microbial cells. This review comprehensively documents recent research on the antimicrobial activity of H2O2 against organisms of concern for the food industry, as well as its effect against SARS-CoV-2 responsible for the COVID-19 pandemic. In addition, factors affecting the antimicrobial effectiveness of H2O2, different applications of H2O2 as a sanitizer or disinfectant in the food industry as well as safety concerns associated with H2O2 are discussed. Finally, recent efforts in enhancing the antimicrobial efficacy of H2O2 are also outlined.

Evaluating the Potential of Ozone Microbubbles for Inactivation of Tulane Virus, a Human Norovirus Surrogate

This study investigated the efficacy of low-dose ozone microbubble solution and conventional aqueous ozone as inactivation agents against Tulane virus samples in water over a short period of time. Noroviruses are the primary cause of foodborne illnesses in the US, and the development of effective inactivation agents is crucial. Ozone has a high oxidizing ability and naturally decomposes to oxygen, but it has limitations due to its low dissolution rate, solubility, and stability. Ozone microbubbles have been promising in enhancing inactivation, but little research has been done on their efficacy against noroviruses. The study examined the influence of the dissolved ozone concentration, inactivation duration, and presence of organic matter during inactivation. The results showed that ozone microbubbles had a longer half-life (14 ± 0.81 min) than aqueous ozone (3 ± 0.35 min). After 2, 10, and 20 min postgeneration, the ozone concentration of microbubbles naturally decreased from 4 ppm to 3.2 ± 0.2, 2.26 ± 0.19, and 1.49 ± 0.23 ppm and resulted in 1.43 ± 0.44, 0.88 ± 0.5, and 0.68 ± 0.53 log10 viral reductions, respectively, while the ozone concentration of aqueous ozone decreased from 4 ppm to 2.52 ± 0.07, 0.43 ± 0.05, and 0.09 ± 0.01 ppm and produced 0.8 ± 0.28, 0.29 ± 0.41, and 0.16 ± 0.21 log10 reductions against Tulane virus, respectively (p = 0.0526), suggesting that structuring of ozone in the bubbles over the applied treatment conditions did not have a significant effect, though future study with continuous generation of ozone microbubbles is needed.

Innovative nonthermal technologies for inactivation of emerging foodborne viruses

Various foodborne viruses have been associated with human health during the last decade, causing gastroenteritis and a huge economic burden worldwide. Furthermore, the emergence of new variants of infectious viruses is growing continuously. Inactivation of foodborne viruses in the food industry is a formidable task because although viruses cannot grow in foods, they can survive in the food matrix during food processing and storage environments. Conventional inactivation methods pose various drawbacks, necessitating more effective and environmentally friendly techniques for controlling foodborne viruses during food production and processing. Various inactivation approaches for controlling foodborne viruses have been attempted in the food industry. However, some traditionally used techniques, such as disinfectant-based or heat treatment, are not always efficient. Nonthermal techniques are considered a new platform for effective and safe treatment to inactivate foodborne viruses. This review focuses on foodborne viruses commonly associated with human gastroenteritis, including newly emerged viruses, such as sapovirus and Aichi virus. It also investigates the use of chemical and nonthermal physical treatments as effective technologies to inactivate foodborne viruses.

Efficacy of EPA-registered disinfectants against two human norovirus surrogates and Clostridioides difficile endospores

AIMS

To determine the efficacy of a panel of nine EPA-registered disinfectants against two human norovirus (HuNoV) surrogates (feline calicivirus [FCV] and Tulane virus [TuV]) and Clostridioides difficile endospores.

METHODS AND RESULTS

Nine EPA-registered products, five of which contained H2 O2 as active ingredient, were tested against infectious FCV, TuV and C. difficile endospores using two ASTM methods, a suspension and carrier test. Efficacy claims against FCV were confirmed for 8 of 9 products. The most efficacious product containing H2 O2 as ingredient achieved a >5.1 log reduction of FCV and >3.1 log reduction of TuV after 5 min, and >6.0 log reduction of C. difficile endospores after 10 min. Of the five products containing H2 O2 , no strong correlation (R2  = 0.25, p = 0.03) was observed between disinfection efficacy and H2 O2 concentration. Addition of 0.025% ferrous sulphate to 1% H2 O2 solution improved efficacy against FCV, TuV and C. difficile.

CONCLUSION

Disinfectants containing H2 O2 are the most efficacious disinfection products against FCV, TuV and C. difficile endospores. Product formulation, rather than the concentration of H2 O2 in a product, impacts the efficacy of a disinfection product.

SIGNIFICANCE AND IMPACT OF STUDY

H2 O2 -based disinfectants are efficacious against surrogate viruses for HuNoV and C. difficile endospores.

Comparative Assessment of the Efficacy of Commercial Hand Sanitizers Against Human Norovirus Evaluated by an in vivo Fingerpad Method

Human noroviruses (hNoV) are the leading cause of acute non-bacterial gastroenteritis worldwide and contaminated hands play a significant role in the spread of disease. Some hand sanitizers claim to interrupt hNoV transmission, but their antiviral efficacy on human hands is poorly characterized. The purpose of this work was to characterize the efficacy of representative commercial hand sanitizers against hNoV using an in vivo fingerpad method (ASTM E1838-17). Eight products [seven ethanol-based and one benzalkonium chloride (BAK)-based], and a benchmark 60% ethanol solution, were each evaluated on 10 human volunteers using the epidemic GII.4 hNoV strain. Virus titers before and after treatment were evaluated by RT-qPCR preceded by RNase treatment; product efficacy was characterized by log₁₀ reduction (LR) in hNoV genome equivalent copies after treatment. The benchmark treatment produced a 1.7 ± 0.5 LR, compared with Product A (containing 85% ethanol) which produced a 3.3 ± 0.3 LR and was the most efficacious (p < 0.05). Product B (containing 70% ethanol), while less efficacious than Product A (p < 0.05), performed better than the benchmark with a LR of 2.4 ± 0.4. Five of the other ethanol-based products (labeled ethanol concentration ranges of 62–80%) showed similar efficacy to the 60% ethanol benchmark with LR ranging from 1.3 to 2.0 (p > 0.05). Product H (0.1% BAK) was less effective than the benchmark with a LR of 0.3 ± 0.2 (p < 0.05). None of the products screened were able to completely eliminate hNoV (maximum assay resolution 5.0 LR). Product performance was variable and appears driven by overall formulation. There remains a need for more hand sanitizer formulations having greater activity against hNoV, a virus that is comparatively recalcitrant relative to other pathogens of concern in community, healthcare, and food preparation environments.

Comparison of virucidal efficacy of sodium hypochlorite, chlorine dioxide, peracetic acid, and ethanol against hepatitis A virus by carrier and suspension tests

A carrier (stainless steel disc as a default carrier) testing method is very needed for use in the actual food-processing fields by following the standard guideline. Here, we aimed to compare the virucidal efficacy of four commercial liquid disinfectants, including sodium hypochlorite (NaOCl), chlorine dioxide (ClO₂), and peracetic acid (PAA) against hepatitis A virus (HAV) following the OECD guideline protocol based on the quantitative carrier testing method and compared carrier testing results with the suspension testing results. The OECD method specifies a test for establishing whether a chemical disinfectant or a microbicide has a virucidal activity on hard non-porous surfaces. The antiviral efficacy was evaluated by plaque assays, and disinfectants were considered effective if the virus reduction was greater than or equal to 3 log₁₀ (99.9% decrease) for carrier or 4 log₁₀ (99.99% decrease) for suspension tests. Results indicated that ClO₂ above 500 ppm and 50% ethanol were effective in the carrier test method. In contrast, more than 200 ppm NaOCl and 50 ppm ClO₂ for all exposure times and 70% ethanol with contact for more than 5 min were effective in suspension tests. Treatment with PAA (80-2500 ppm) were not effective in carrier or suspension tests. Therefore, we recommend the use of more than 500 ppm ClO₂ or 50% ethanol with exposure for 10 min to disinfect surfaces that may be contaminated with HAV. Thus, these results could be effective in establishing official antiviral efficacy testing methods and basic data.

Application of Chitosan Microparticles against Human Norovirus

ABSTRACT

Human norovirus (HuNoV) is the leading cause of foodborne illness outbreaks and the second most common cause of waterborne infections in the United States. The goal of this research was to investigate the antiviral activity of chitosan microparticles (CMs) against HuNoV GII.4 Sydney and its cultivable surrogate Tulane virus (TuV) in suspensions mimicking fecally contaminated water. CMs were prepared by cross-linking chitosan molecules with sodium sulfate, and the antiviral activity of CMs was assessed with an infectivity assay on TuV and by quantitative reverse transcription PCR on TuV and HuNoV. A 3% CM suspension in phosphate-buffered saline (pH 7.2) bound to TuV particles but had a negligible impact on virus infectivity (P > 0.05). A 10-min contact time resulted in a 1.5-log reduction in genomic copies per mL of TuV and HuNoV in fecal suspensions (P < 0.05). Despite the negligible impact on viral infectivity, CMs can moderately bind to infectious virus particles and help purify environmental water by removing these particles. In this study, TuV was a suitable surrogate for HuNoV with similar log reductions in fecal suspension. These findings highlight the potential application of CM as a novel treatment to minimize the spread of waterborne viral pathogens.

HIGHLIGHTS

Optimizing Operating Parameters of Electric Ultra-Low Volume Sprayer with Slightly Acidic Electrolyzed Solution for Efficient Virucidal Activity on Environmental Surfaces

Recently, and considering the COVID-19 pandemic, there has been a growing consensus that the disinfection of surfaces contaminated with pathogenic viral particles is essential. Chemical disinfectant sprays are effective at preventing the spread of infectious human noroviruses (Hu-NoVs) in healthcare and public areas. We assessed the virucidal activity of slightly acidic electrolyzed water (SAEW) spray on fomite surfaces. A multivariate statistical assessment that combined a response surface methodology (RSM) and a Box–Behnken design (BBD) was performed to define the optimal parameters of, and correlations among, experimental conditions. Spraying SAEW disinfectant (oxidation-reduction potential: 1123 mV, pH range: 5.12, available chlorine concentration: 33.22 ppm) resulted in the successful decontamination of Hu-NoV, with a 4-log reduction in viral particles on polyvinyl chloride, stainless steel, ceramic tile, and glass surfaces. Our experimental data revealed optimized treatment conditions for decontaminating Hu-NoV GI.6 and GII.4, using the numerical multiple optimized method (spraying rate: 218 mL/min, spraying time: 4.9 s, spraying distance: 0.9 m). These findings offer significant insights for designing optimal strategic control practices to prevent infectious disease, particularly Hu-NoV, transmission.

COVID-19 and environment: a poignant reminder of sustainability in the new normal

The nexus of COVID-19 and environment is conspicuously deep-rooted. The roles of environmental factors in the origin, transmission and spread of COVID-19 and the mutual impact of the pandemic on the global environment have been the two perspectives to view this nexus. The present paper attempts to systematically review the existing literature to understand and explore the linkages of COVID-19 with environment and proposes conceptual frameworks to underline this nexus. Our study indicates a critical role of meteorological factors, ambient air pollutants and wastewater in severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) transmission-spread dynamics. The study also focuses on the direct and indirect impacts of COVID-19 on the regional and global environment. Most of the indirect environmental effects of COVID-19 were attributed to global human confinement that resulted from the implementation of the pandemic containment measures. This worldwide anthropogenic 'pause' sent ripples to all environmental compartments and presented a unique test bed to identify anthropogenic impacts on the earth's natural systems. The review further addresses emerging sustainability challenges in the new normal and their potential solutions. The situation warrants critical attention to the environment-COVID-19 nexus and innovative sustainable practices to address the ramifications of short- and long-term environmental impacts of the COVID-19 pandemic.

Graphical abstract

Kinetic Modeling of Slightly Acidic Electrolyzed Water Decay Characteristics in Fresh Cabbage Disinfection Against Human Norovirus

To consistently disinfect fresh vegetables efficiently, the decay of disinfectants such as chlorine, electrolyzed oxidizing water (EOW), ozonated water, and plasma-activated water during the disinfection maintenance stage needs to be understood. The aim of our study was to evaluate the changes in the inactivation kinetics of slightly acidic electrolyzed water (SAEW) against human norovirus (HuNoV), based on the cabbage-to-SAEW ratio. After disinfection of fresh cabbage with disinfected SAEW solution, SAEW samples were collected and analyzed for physicochemical properties such as pH, available chlorine concentrations (ACCs), and oxidation-reduction potential (ORP). SAEW virucidal effects were evaluated. We confirmed the decay of post-disinfection SAEW solution and demonstrated the different patterns of the decay kinetic model for HuNoV GI.6 and GII.4. In addition, the goodness of fit of the tested models based on a lower Akaike information criterion, root-mean-square error (RMSE), and residual sum of squares (RSS) was close to zero. In particular, the change in both the HuNoV GI.6 and GII.4 inactivation exhibited a strong correlation with the changes in the ACC of post-disinfection SAEW. These findings demonstrate that physicochemical parameters of SAEW play a key role in influencing the kinetic behavior of changes in the disinfection efficiency of SAEW during the disinfection process. Therefore, to optimize the efficiency of SAEW, it is necessary to optimize the produce-to-SAEW ratio in future studies.

Contamination, bioaccumulation mechanism, detection, and control of human norovirus in bivalve shellfish: A review

Human norovirus (HuNoV) is a major foodborne pathogen that causes acute viral gastroenteritis, and bivalve shellfish are one of the main carriers of HuNoV transmission. A comprehensive understanding of bivalve shellfish-related HuNoV outbreaks focusing on contamination factors, bioaccumulation mechanisms, and pre- and post-harvest interventions is essential for the development of effective strategies to prevent contamination of shellfish. This review comprehensively surveys the current knowledge on global contamination and non-thermal treatment of HuNoV in bivalve shellfish. HuNoV contamination in bivalve shellfish is significantly related to the season and water. While evaluating the water quality of shellfish-inhabited waters is a key intervention, the development of non-heat treatment technology to effectively inactivate the HuNoV in bivalve shellfish while maintaining the flavor and nutrition of the shellfish is also an important direction for further research. Additionally, this review explores the bioaccumulation mechanisms of HuNoV in bivalve shellfish, especially the mechanism underlying the binding of histo-blood group antigen-like molecules and HuNoV. The detection methods for infectious HuNoV are also discussed. The establishment of effective methods to rapidly detect infectious HuNoV and development of biological components to inactivate or prevent HuNoV contamination in shellfish also need to be studied further.

Photocatalytic inactivation of viral particles of human norovirus by Cu-doped TiO2 non-woven fabric under UVA-LED wavelengths

Metal-doped TiO₂ photocatalysis are recognized as effective materials for eliminating human norovirus (HuNoVs). In recent years, the airborne transmission of viral particles of HuNoVs has been a cause for concern. In this study, we evaluated the virucidal effects of a Cu/TiO₂ non-woven fabric (NWF) on viral particles of HuNoV genogroup II genotype 4 (HuNoV GII.4) under an ultraviolet A light-emitting diode (UVA-LED) source. For the optimized parameters, a multivariate statistical analysis using the Box-Behnken design (BBD) technique combined with the response surface methodology (RSM) was applied. The experimental results showed that the Cu/TiO₂-based NWF degraded HuNoV viral particles in the air samples. The BBD-based RSM indicated that the optimum treatment conditions for inactivating the HuNoV GII.4 droplets with the Cu/TiO₂ NWF were a 1:7.7 ratio of Cu:TiO₂ and the use of a 373-nm UVA-LED source for 48.08 min. The optimal conditions for the photocatalytic efficacy in HuNoV GII.4 of Cu/TiO₂ NWF were verified experimentally, giving a value of 2.89 ± 0.11 log₁₀ genomic copies, which was the same as the predicted value (2.91611) within experimental uncertainty. This result adequately validated the predicted model and confirmed that viral particles of HuNoVs could efficiently be disinfected using Cu/TiO₂ NWF stimulated by UVA-LED light.

Virucidal efficacy of food additive grade calcium hydroxide against surrogate of human norovirus

An alkaline agent, namely, food additive grade calcium hydroxide (FdCa(OH)₂) in the solution, powder and suspension forms was evaluated as a virucidal agent, using a murine norovirus (MNV) as the surrogate for human norovirus. The main constituent of FdCa(OH)₂ is Ca(OH)₂, which has pH 13 in 0.17% solution. The results showed that 0.17% FdCa(OH)₂ solution could inactivate MNV within 30s even in the presence of organic materials (5% fetal bovine serum (FBS)). In a contaminated surface experiment, MNV with 5% FBS was inoculated on rayon sheets, and the result showed FdCa(OH)₂ solution could markedly reduce virus titer within 1min. When mouse feces were spiked with MNV and FdCa(OH)₂ powder as 10% and 20% w/w was added to the feces, these concentrations could inactivate the virus within 30min and 15min, respectively. Whereas, FdCa(OH)₂ suspension at 2.5% and 5% could inactivate the virus within 30min and at 1% within 45min. These and additional results obtained here indicate that FdCa(OH)₂ is an effective virucidal agent against MNV, and can serve as a useful alternative disinfectant for inactivation and prevention of human norovirus in house and hospital.