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.

Environmental persistence and transfer of enteric viruses.

Non-enveloped enteric viruses, such as Human Norovirus and Hepatitis A Virus, are readily transmitted via the fecal-oral route. Outbreaks are often prolonged due to the ability of these viruses to survive on environmental surfaces, on foods, and in water. Delineation of properties impacting enteric virus transfer and persistence in the environment has been the focus of several recent publications and is the topic of this review. Such information is important for modeling transmission scenarios, identifying risks of food-borne and water-borne virus contamination, and targeting prevention and control efforts for risk mitigation.

Human norovirus transfer to stainless steel and small fruits during handling.

Human noroviruses (NoVs) cause an estimated 58% of foodborne illnesses in the United States annually. The majority of these outbreaks are due to contamination by food handlers. The objective of this study was to quantify the transfer rate and degree of contamination that occurs on small fruits (blueberries, grapes, and raspberries) and food contact surfaces (stainless steel) when manipulated with NoV-contaminated hands. Human NoVs (genogroups I and II [GI and GII]) and murine norovirus (MNV-1) were inoculated individually or as a three-virus cocktail onto donor surfaces (gloved fingertips or stainless steel) and either immediately interfaced with one or more recipient surfaces (fruit, gloves, or stainless steel) or allowed to dry before contact. Viruses on recipient surfaces were quantified by real-time quantitative reverse transcriptase PCR. Transfer rates were 58 to 60% for GII NoV from fingertips to stainless steel, blueberries, and grapes and 4% for raspberries under wet conditions. Dry transfer occurred at a much lower rate (<1%) for all recipient surfaces. Transfer rates ranged from 20 to 70% from fingertips to stainless steel or fruits for the GI, GII, and MNV-1 virus cocktail under wet conditions and from 4 to 12% for all viruses under dry transfer conditions. Fomite transfer (from stainless steel to fingertip and then to fruit) was lower for all viruses, ranging from 1 to 50% for wet transfer and 2 to 11% for dry transfer. Viruses transferred at higher rates under wet conditions than under dry conditions. The inoculum matrix affected the rate of virus transfer, but the majority of experiments resulted in no difference in the transfer rates for the three viruses. While transfer rates were often low, the amount of virus transferred to recipient surfaces often exceeded 4- or 5-log genomic copy numbers, indicating a potential food safety hazard. Quantitative data such as these are needed to model scenarios of produce contamination by food handling and devise appropriate interventions to manage risk.