Studies on heat inactivation of hepatitis A virus with special reference to shellfish: Part 1. Procedures for infection and recovery of virus from laboratory-maintained cockles

Contaminated food is a significant vehicle for human norovirus transmission. The present study determined the effect of physicochemical treatments on the tenacity of infective human norovirus genogroup II in selected foods. Artificially contaminated produce was subjected to a number of processes used by the food industry for preservation and by the consumer for storage and preparation. Virus recovery was carried out by using ultrafiltration and was monitored by using bacteriophage MS2 as an internal process control. Norovirus was quantified by using monoplex one-step TaqMan real-time reverse transcription (RT)-PCR and an external standard curve based on recombinant RNA standards. An RNase pretreatment step was used to avoid false-positive PCR results caused by accessible RNA, which allowed detection of intact virus particles. Significant reductions in titers were obtained with heat treatments usually applied by consumers for food preparation (baking, cooking, roasting). Generally, processes used for preservation and storage, such as cooling, freezing, acidification (>pH 4.5), and moderate heat treatments (pasteurization), appear to be insufficient to inactivate norovirus within a food matrix or on the surface of food. Besides data for persistence in processed food, comparable data for individual matrix-specific protective effects, recovery rates, and inhibitory effects on the PCRs were obtained in this study. The established procedure might be used for other noncultivable enteric RNA viruses that are connected to food-borne diseases. The data obtained in this study may also help optimize the process for inactivation of norovirus in food by adjusting food processing technologies and may promote the development of risk assessment systems in order to improve consumer protection.Norovirus (NV) (formerly Norwalk-like virus) is a member of the family Caliciviridae and is a nonenveloped virus with a single-stranded RNA (ssRNA) genome. Genetically, the human noroviruses are subdivided into three distinct genogroups (genogroup I [GGI], GGII, and GGIV) and into at least 31 genetic clusters or genotypes (53). Noroviruses have emerged as the most common cause of food-borne outbreaks and sporadic cases of acute nonbacterial gastroenteritis worldwide (62,87).In addition to direct person-to-person infection, transmission via environmental contamination (70) and transmission via foods and drinking water (primary and secondary contamination) are known. Food can be contaminated by contact with sewage or sewage water before harvest; e.g., shellfish (3,52,58,60,81) and raspberries (33, 72) have been reported to be vehicles of NV infection. Food is often directly contaminated during production, storage, distribution, and preparation by infected persons (22); e.g., ill or asymptomatic food handlers have been identified as sources of virus contamination of fresh produce and ready-to-eat foods (25, 69). The percentage of cases that can be attributed to food-or waterborne transmission is estimated to be between 16% (56) and 57% (34). Hu...

Section: Discussionsupporting

confidence: 91%

mentioning

confidence: 99%

Effects of Technological Processes on the Tenacity and Inactivation of Norovirus Genogroup II in Experimentally Contaminated Foods

Mormann¹,

Dabisch²,

Becker³

2010

“…In order to evaluate the effects of food matrix composition on thermal inactivation, the levels of resistance of HAV were compared in several food samples. Thermal inactivation studies for HAV have involved cell culture medium, spinach, shellfish, mussels, clams, cockles, and milk; reported D values for HAV in the range of 50 to 100°C were 0.01 to 385 min (26,27,(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50). According to the product description, the composition of the turkey deli meat included sodium (10 mg/g), fat (0.8%), carbohydrates (1.7%), protein (19%), and moisture (77%).…”

Section: Resultsmentioning

confidence: 99%

Thermal Inactivation Kinetics of Human Norovirus Surrogates and Hepatitis A Virus in Turkey Deli Meat

Bozkurt

D’Souza

Davidson

2015

4), in a publication on the incidence and causes of foodborne illnesses in the United States, reported that a large number of outbreaks are caused by HNoV (58%). Additionally, relatively high hospitalization and death rates are associated with HAV infection (32% and 2%, respectively) (1, 4).According to the U.S. Food and Drug Administration (FDA) and U.S. Department of Agriculture Food Safety and Inspection Service (FSIS), deli meat has posed the highest per annum risk of illness and death among poultry products (5). Additionally, in other studies, Gould et al. (6) and Painter et al. (7) studied surveillance and attribution of foodborne disease outbreaks in the United States from 1998 to 2008. They found that, among individual food categories, poultry was the most commonly reported food vehicle of disease, causing 17% of outbreaks of foodborne illness (6), and that the proportions of poultry-associated foodborne illnesses, hospitalizations, and deaths caused by human noroviruses and HAV were 28%, 14%, and 4%, respectively (7). In 1998 through 2002 alone, three large outbreaks were linked to the consumption of turkey delicatessen meat contaminated during processing (7). Since ready-to-eat (RTE) meat and poultry deli products can be consumed without further cooking, these products should be free of non-spore-forming pathogens following the industrial thermal process. However, they can become contaminated before packaging in the final retail wrap and thus pose a safety threat for consumers (8,9). Viral contamination of RTE and prepared foods most frequently comes from poor hand-washing practices of food handlers after toilet use. Fecal material can be left on hands or even under nails which then can come in contact with food products (10). Handling cooked products with bare hands has been identified as a major factor for pathogen transfer to RTE foods (11), and there is presumed to be a direct correlation between the number of pathogenic organisms on a food employee's hands and the probability of microbial transfer from hands to cooked food products (12). Since the contamination most likely occurs at the surface, it seems advisable to decontaminate the outer layer of products. For this purpose, postpackage pasteurization technologies could be practiced as a method for reducing surface contamination by food pathogens (9). One of the challenges for the industry would be to assess the required time and temperature combination, which would depend on the thermal inactivation kinetics of the target microorganism (13). It has been reported that foodborne enteric viruses are more heat resistant than most non-spore-forming bacterial foodborne pathogens (14); thus, processing recommendations based on the data for non-spore-forming bacteria may not eliminate similar numbers of foodborne enteric viruses. Since there is no specific federal regulation covering the minimum time-temperature combinations for inactivating virus in contaminated deli meat, establishment of potential thermal processes for inactivating human norovirus...

“…Remarkably, Slomka and Appleton (39) reported a comparable 3 D inactivation in 0.5 to 1 min of FeCV in contaminated cockles at 80°C, indicating that FeCV, unlike hepatitis A virus (2,29), is not significantly stabilized by factors such as fat and high protein content.…”

Section: Discussionmentioning

confidence: 97%

Inactivation of Caliciviruses

Duizer

Bijkerk

Rockx

et al. 2004

328

246

The viruses most commonly associated with food-and waterborne outbreaks of gastroenteritis are the noroviruses. The lack of a culture method for noroviruses warrants the use of cultivable model viruses to gain more insight on their transmission routes and inactivation methods. We studied the inactivation of the reported enteric canine calicivirus no. 48 (CaCV) and the respiratory feline calicivirus F9 (FeCV) and correlated inactivation to reduction in PCR units of FeCV, CaCV, and a norovirus. Inactivation of suspended viruses was temperature and time dependent in the range from 0 to 100°C. UV-B radiation from 0 to 150 mJ/cm 2 caused dose-dependent inactivation, with a 3 D (D ‫؍‬ 1 log 10 ) reduction in infectivity at 34 mJ/cm 2 for both viruses. Inactivation by 70% ethanol was inefficient, with only 3 D reduction after 30 min. Sodium hypochlorite solutions were only effective at >300 ppm. FeCV showed a higher stability at pH <3 and pH >7 than CaCV. For all treatments, detection of viral RNA underestimated the reduction in viral infectivity. Norovirus was never more sensitive than the animal caliciviruses and profoundly more resistant to low and high pH. Overall, both animal viruses showed similar inactivation profiles when exposed to heat or UV-B radiation or when incubated in ethanol or hypochlorite. The low stability of CaCV at low pH suggests that this is not a typical enteric (calici-) virus. The incomplete inactivation by ethanol and the high hypochlorite concentration needed for sufficient virus inactivation point to a concern for decontamination of fomites and surfaces contaminated with noroviruses and virus-safe water.