Evaluation of the Impact of Compliance with Mitigation Strategies and Frequency of Restaurant Surface Cleaning and Sanitizing on Control of Norovirus Transmission from Ill Food Employees Using an Existing Quantitative Risk Assessment Model.

ABSTRACT: Reduction of foodborne illness caused by norovirus (NoV) continues to be a focus for the food safety community. Using a previously published quantitative risk assessment model, we evaluated more than 60 scenarios examining the impact of implementation of and compliance with risk management strategies identified in the U.S. Food and Drug Administration Food Code for (a) surface cleaning and sanitizing, (b) hand hygiene, (c) exclusion, or (d) restriction of ill employees. Implementation of and compliance with hand hygiene and ill food employee exclusion strategies had the largest impact on the predicted number of highly contaminated food servings and associated consumer illnesses. In scenarios in which gloves were always worn and hand washing compliance was 90%, the model estimated reductions in the number of highly contaminated food servings and ill consumers to 39 and 43% of baseline estimates (i.e., typical practice), respectively. Reductions were smaller when gloves were never worn. Hand washing compliance after using the restroom strongly impacted predicted numbers of highly contaminated servings and consumer illnesses. Ten percent compliance with removing or excluding ill food employees was predicted to increase the number of highly contaminated food servings and ill consumers to 221 and 213% of baseline estimates, respectively. Ninety-four percent compliance with exclusion of ill food employees was predicted to decrease these numbers to 69 and 71% of baseline estimates, respectively. Surface cleaning in food establishments had a relatively small impact on these measures. Restriction of food employees (removed from contact with food and food contact equipment and utensils) was not effective for reducing NoV illness unless this restriction included additional provisions. The results from this study can help risk managers prioritize mitigation strategies and their implementation for controlling the transmission of NoV and subsequent consumer foodborne illness.

Toward a Better Understanding of Listeriosis Risk among Older Adults in the United States: Characterizing Dietary Patterns and the Sociodemographic and Economic Attributes of Consumers with These Patterns.

ABSTRACT: Older adults are at higher risk of invasive listeriosis compared with the general population. Some foods are more likely than others to be contaminated with or to contain high levels of Listeria monocytogenes. The objectives of this study were to (i) determine dietary consumption patterns among older adults in the United States; (ii) evaluate sociodemographic and economic characteristics of older adults associated with each pattern; (iii) determine intake of foods associated with larger relative risk of listeriosis within these patterns; and (iv) rank these patterns based on risk. Data related to older adults (age 60 and older) participating in the cross-sectional National Health and Nutrition Examination Surveys (NHANES) 2009 to 2010, 2011 to 2012, and 2013 to 2014 (n = 4,967) were included in these analyses. Cluster analysis was used to define dietary patterns based on 24-h dietary recalls from day 1 and day 2. Mean intake of foods associated with higher risk of listeriosis was examined within each pattern, and analysis of variance with Dunnett's method of adjustment was used to evaluate significant differences in mean intake of foods. Patterns were ranked based on relative risk of listeriosis, using outbreak illness attribution data. Five distinct dietary patterns were identified. Patterns ranked at highest relative risk of listeriosis, based on U.S. outbreak illness attribution data, were characterized by relatively higher intakes of fruits, vegetables, and cheeses (∼13% respondents) or cereal, milk, and yogurt (∼14% respondents). Individuals consuming these dietary patterns differed in sex, race, food security, self-rated diet quality, and self-rated health. Cluster analysis, despite methodological limitations, provides new information on consumption, sociodemographic, and economic characteristics of subgroups within susceptible populations, which may be used to target educational messages.

A Quantitative Risk Assessment of Human Salmonellosis from Consumption of Pistachios in the United States.

We developed a quantitative risk assessment model to assess the risk of human nontyphoidal salmonellosis from consumption of pistachios in the United States and to evaluate the impact of Salmonella treatments (1- to 5-log reductions). The exposure model estimating prevalence and contamination levels of Salmonella at consumption included steps in pistachio processing such as transport from grower to huller, removal of the hull through wet abrasion, separation of pistachio floaters (immature, smaller nuts) and sinkers (mature, larger nuts) in a flotation tank, drying, storage, and partitioning. The risks of illness per serving and per year were evaluated by including a Salmonella dose-response model and U.S. consumption data. The spread of Salmonella through float tank water, delay in drying resulting in growth, increased Salmonella levels through pest infestation during storage (pre- and posttreatment), and a simulation of the 2016 U.S. salmonellosis outbreak linked to consumption of pistachios were the modeled atypical situations. The baseline model predicted one case of salmonellosis per 2 million servings (95% CI: one case per 5 million to 800,000 servings) for sinker pistachios and one case per 200,000 servings (95% CI: one case per 400,000 to 40,000 servings) for floater pistachios when no Salmonella treatment was applied and pistachios were consumed as a core product (>80% pistachio) uncooked at home. Assuming 90% of the pistachio supply is sinkers and 10% is floaters, the model estimated 419 salmonellosis cases per year (95% CI: 200 to 1,083 cases) when no Salmonella treatment was applied. A mean risk of illness of less than one case per year was estimated when a minimum 4-log reduction treatment was applied to the U.S. pistachio supply, similar to the results of the Salmonella risk assessment for almonds. This analysis revealed that the predicted risk of illness per serving is higher for all atypical situations modeled compared with the baseline, and delay in drying had the greatest impact on consumer risk.

Prevalence of Salmonella in 11 Spices Offered for Sale from Retail Establishments and in Imported Shipments Offered for Entry to the United States.

The U.S. Food and Drug Administration conducted a survey to evaluate Salmonella prevalence and aerobic plate counts in packaged (dried) spices offered for sale at retail establishments in the United States. The study included 7,250 retail samples of 11 spice types that were collected during November 2013 to September 2014 and October 2014 to March 2015. No Salmonella-positive samples (based on analysis of 125 g) were found among retail samples of cumin seed (whole or ground), sesame seed (whole, not roasted or toasted, and not black), and white pepper (ground or cracked), for prevalence estimates of 0.00% with 95% Clopper and Pearson's confidence intervals of 0.00 to 0.67%, 0.00 to 0.70%, and 0.00 to 0.63%, respectively. Salmonella prevalence estimates (confidence intervals) for the other eight spice types were 0.19% (0.0048 to 1.1%) for basil leaf (whole, ground, crushed, or flakes), 0.24% (0.049 to 0.69%) for black pepper (whole, ground, or cracked), 0.56% (0.11 to 1.6%) for coriander seed (ground), 0.19% (0.0049 to 1.1%) for curry powder (ground mixture of spices), 0.49% (0.10 to 1.4%) for dehydrated garlic (powder, granules, or flakes), 0.15% (0.0038 to 0.83%) for oregano leaf (whole, ground, crushed, or flakes), 0.25% (0.03 to 0.88%) for paprika (ground or cracked), and 0.64% (0.17 to 1.6%) for red pepper (hot red pepper, e.g., chili, cayenne; ground, cracked, crushed, or flakes). Salmonella isolates were serotyped, and genomes were sequenced. Samples of these same 11 spice types were also examined from shipments of imported spices offered for entry to the United States from 1 October 2011 to 30 September 2015. Salmonella prevalence estimates (based on analysis of two 375-g composite samples) for shipments of imported spices were 1.7 to 18%. The Salmonella prevalence estimates for spices offered for sale at retail establishments for all of the spice types except dehydrated garlic and basil were significantly lower than estimates for shipments of imported spice offered for entry.

A Quantitative Assessment of the Risk of Human Salmonellosis Arising from the Consumption of Pecans in the United States.

A quantitative risk assessment was conducted to assess the risk of human salmonellosis acquired from consumption of pecans in the United States. The model considered the potential for Salmonella survival, growth, and recontamination of pecans from the sheller to the consumer, including steps such as immersion in water, drying, conditioning, cracking, partitioning, and storage. Five theoretical microbial reduction treatment levels (1 to 5 log CFU) were modeled. Data from the 2010 to 2013 surveys by the National Pecan Shellers Association were used for initial prevalence and contamination levels. The impacts of atypical situations in the pecan production system were also evaluated. Higher initial contamination levels, recontamination during processing, and a delay in drying postconditioning were the modeled atypical situations. The baseline model predicted a mean risk of salmonellosis in the United States from consumption of in-shell and shelled pecans processed by cold conditioning with no microbial reduction treatment and no further home cooking as 1 case per 775,193 servings (95% confidence interval [CI]: 1 case per 1,915,709 to 178,253 servings). This predicted risk per serving was estimated as a mean of 529 cases of salmonellosis per year (95% CI: 213 to 2,295 cases). Hot conditioning for shelled pecans and microbial reduction treatment of both shelled and in-shell pecans had a significant impact on the predicted mean risk of illness. Assuming 77% of the shelled pecans sold at retail (i.e., 80% of the retail supply) received hot conditioning, the mean estimated salmonellosis cases per year from consumption of in-shell and shelled pecans uncooked at home was 203 (95% CI: 81 to 882 cases) if no additional microbial reduction treatment were applied. The predicted risk of illness per serving was higher for all atypical situations modeled compared with the baseline model, and delay in drying had the greatest impact on risk.

A Quantitative Assessment of the Risk of Human Salmonellosis Arising from the Consumption of Almonds in the United States: The Impact of Preventive Treatment Levels.

The presence of Salmonella on almonds continues to result in product-related outbreaks and recalls in the United States. In this study, the impact of microbial reduction treatment levels (1 to 5 log CFU) on the risk of human salmonellosis from the consumption of almond kernels in the United States was evaluated. An exposure model, including major steps in almond processing, was used to estimate prevalence and levels of contamination of Salmonella on almonds at the point of consumption. A Salmonella dose-response model and consumption data for almonds in the United States were used to assess risk of illness per serving and per year, quantifying variability and uncertainty separately. A 3-log reduction treatment resulted in a predicted mean risk of illness of two cases per year for almonds consumed as a core product not cooked at home (95% confidence interval [CI], one to four cases), one case per year for almonds consumed as an ingredient not cooked at home (95% CI, one to two cases), and less than one case per year for almonds consumed as an ingredient cooked at home (95% CI, 7 × 10-7 to 3 × 10-6 cases). A minimum 4-log reduction treatment resulted in an estimated mean risk of illness below one case per year in the United States. This study also includes an assessment of the risk of human salmonellosis as a result of an exceptional situation, which results in higher risk estimates compared with the baseline model. The exceptional situations modeled posttreatment resulted in estimates of mean risk that were not significantly affected by treatment level. Sensitivity analysis results showed initial Salmonella contamination level to be the factor with the most impact on risk per serving estimates, given a certain treatment level. The risk assessment also includes a simulation of the events that occurred in 2001. Treatment levels with a minimum 4-log microbial reduction would have been sufficient to prevent the outbreak cases. The uncertainty range in the estimates indicates that additional information is needed to make more precise predictions of this specific outbreak event.

Prevalence of Salmonella in Cashews, Hazelnuts, Macadamia Nuts, Pecans, Pine Nuts, and Walnuts in the United States.

Nuts have been identified as a vector for salmonellosis. The objective of this project was to estimate the prevalence and contamination level of Salmonella in raw tree nuts (cashews, pecans, hazelnuts, macadamia nuts, pine nuts, and walnuts) at retail markets in the United States. A total of 3,656 samples of six types of tree nuts were collected from different types of retail stores and markets nationwide between October 2014 and October 2015. These samples were analyzed using a modified version of the Salmonella culture method from the U.S. Food and Drug Administration's Bacteriological Analytical Manual. Of the 3,656 samples collected and tested, 32 were culturally confirmed as containing Salmonella. These isolates represented 25 serotypes. Salmonella was not detected in pecans and in-shell hazelnuts. Salmonella prevalence estimates (and 95% confidence intervals) in cashews, shelled hazelnuts, pine nuts, walnuts, and macadamia nuts were 0.55% [0.15, 1.40], 0.35% [0.04, 1.20], 0.48% [0.10, 1.40], 1.20% [0.53, 2.40], and 4.20% [2.40, 6.90], respectively. The rates of Salmonella isolation from major or big chain supermarkets, small chain supermarkets, discount, variety, or drug stores, and online were 0.64% [0.38, 1.00], 1.60% [0.80, 2.90], 0.00% [0.00, 2.40], and 13.64% [2.90, 35.00], respectively (Cochran-Mantel-Haenszel test: P = 0.02). The rates of Salmonella isolation for conventional and organic nuts were not significantly different. Of the samples containing Salmonella, 60.7% had levels less than 0.003 most probable number (MPN)/g. The highest contamination level observed was 0.092 MPN/g. The prevalence and levels of Salmonella in these tree nut samples were comparable to those previously reported for similar foods.