Letter Report on the Review of the Food Safety and Inspection Service Proposed Risk-Based Approach to and Application of Public-Health Attribution (2009) / Chapter Skim
Currently Skimming:
Letter Report
Letter Report
Pages 1-27
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 1... ...
The committee was selected to include expertise in food science, food safety, meat processing, microbiology, biostatistical sampling, microbial-risk assessment, foodborne-disease epidemiology, and disease attribution. The committee was tasked with evaluating the proposed FSIS methodology and the adequacy of the data used to estimate foodborne-disease attribution for the purpose of ranking slaughtering and processing establishments according to public-health risk.
|
From page 2... ...
Bailar III, Chair Committee for Review of the Food Safety and Inspection Service Risk-Based Approach to Public-Health Attribution 2
|
From page 3... ...
outbreak data and expert elicitations to develop betterinformed attribution estimates. For example, the CDC outbreak database can be mined further to obtain additional information on sources of contamination.
|
From page 4... ...
stated, "the Committee concludes that science-based food safety criteria must be clearly linked to the public health problem they are designed to address. To accomplish this, a cause/effect relationship needs to be established between contaminants in foods and human disease, that is, to allocate the burden of foodborne disease among foods and food groups" (p.
|
From page 5... ...
Dreyling, FSIS, unpublished material, January 6, 2009) are not consistent, so attribution estimates based on the two documents differ.2 FSIS presented the attribution estimates derived from the two expert elicitations and the CDC outbreak data and then compared them; finding excellent agreement among the three estimates.
|
From page 6... ...
, in particular the CDC outbreak data. FSIS combined the three data sets to develop their attribution estimates.
|
From page 7... ...
Attribution Estimates for Developing Performance Objectives FSIS also intends to use public-health attribution data to develop performance objectives on the basis of CDC Healthy People 2010 goals for E coli O157:H7 in ground beef, L
|
From page 8... ...
isolated from animal and food sources and from human clinical specimens. The subtyping information is often collated with results of epidemiologic surveillance programs and mathematical modeling to estimate attribution.
|
From page 9... ...
, which, in addition to active surveillance, conducts case-control studies of sporadic illnesses and population surveys to determine background rates of diarrheal illness and exposure to various food items. Trends in the occurrence of foodborne diseases under active surveillance by FoodNet since 1996 have been important in establishing consistent methods for capturing data on foodborne illness.
|
From page 10... ...
risk factors for disease; design, including ability to limited resolution for commonly persons with respect to calculation of population- explore multiple exposures consumed foods, establishing previous exposures; relative attributable to estimate (specific foods, food-preparation temporality; many cases required role of exposure is determined relative importance of practices, cross-contamination, for adequate statistical power; by comparing frequencies in different exposures travel, other risk factors) usually limited to single cases and controls microorganism rather than multiple agents; expensive Microbial subtyping Integrated, active surveillance Best suited for pathogens that are Usually applied to single Hald et al.
|
From page 11... ...
2008 Yields mathematically derived and uncertainty distributions commodities; theoretically, can accompanied by uncertainty estimates of risk for estimates; logic model of integrate data obtained from analysis) ; resource-intensive how parameters are related to national surveillance programs each other Expert elicitation More explicit, structured, Best suited for filling in data Subjective in nature; potential for Hoffmann et al.
|
From page 12... ...
Those criteria substantially increase the specificity of the definition of an outbreak and help to reduce the number of foodborne-illness complaints that are reported as outbreaks. Because epidemiologic investigation is needed to confirm a food-related outbreak, outbreak databases constitute a useful source of information, because the grouping of cases as part of an outbreak allows the comparison of exposure histories (that is, information on who is being exposed and the level of exposure)
|
From page 13... ...
2007) generally support the use of outbreak data for attribution purposes in large part because the primary vehicles associated with the outbreaks are also identified as contributors to the occurrence of the sporadic infections.
|
From page 14... ...
Use of Molecular Subtyping Information on Salmonella to Enhance Attribution Efforts Background Serotyping, a method used to classify microorganisms on the basis of their cell-surface antigens, has been used for several decades to characterize Salmonella isolates. More than 2,500 Salmonella serotypes have been reported, but only about 20 are responsible for about 70% of cases of human salmonellosis in the United States (CDC 2008b)
|
From page 15... ...
However, assembling sufficiently large datasets for alternate subtyping methods for source attribution may be time and cost intensive.) Because both food and nonfood vehicles can be sources of human Salmonella infections, there is considerable interest in developing accurate estimates of the relative contributions of different exposures to the total number of human cases.
|
From page 16... ...
How closely the QMRA model describes the actual scenario being studied will also affect the accuracy of the conclusions. QMRA risk estimates may be validated by using epidemiologic data; however, the usefulness of epidemiologic data is often limited, especially if QMRA considers specific food products in a larger food-product category (such as ground beef in the beef category)
|
From page 17... ...
2007a) used structured expert elicitation to estimate the association of pathogens with specific food commodities, and Karns et al.
|
From page 18... ...
Interventions that reduce the likelihood and magnitude of contamination in raw meats would also reduce cross-contamination risks, but these were not considered in either expertelicitation study. Comparisons of Expert Elicitation and Outbreak Data Descriptions of how well expert opinion correlated with outbreak data are provided by Hoffmann et al.
|
From page 19... ...
FSIS (2008c) , likewise, acknowledges that no single source of information can provide a comprehensive picture of food-source attribution and has identified several datasets that could be used to establish improved attribution estimates, including CDC outbreak data; results of FoodNet case-control studies; FSIS and FDA risk assessments; CDC, FDA, and FSIS Salmonella serotype data; and expert elicitation.
|
From page 20... ...
Although the committee was tasked with examining only the "public-health impact" calculation that feeds into the public-health risk ranking, it considers that because the "indicators of process control" and the LOI categorization are intimately linked with the "public-health impact" (the product of attribution and fractional volume) , it is difficult to evaluate the effectiveness of ranking by attribution and fractional volume without also evaluating the LOI categorization.
|
From page 21... ...
coli O157:H7 cases attributable to specific FSIS product categories was revised in the January 7 version; the greatest changes were in ground beef and other raw ground meat. The public-health risk ranking of establishments changed with the change in attribution estimates.
|
From page 22... ...
The validity of the algorithm depends on an evaluation of the assumptions in the model, which includes an evaluation of the LOI categorization and how it interacts with the potential public health impact. BOX 4 llustration of Interaction of Fractional Volume and Pathogen Attribution Estimates in Estimating Public Health Impact for Plant Number 2 RTE Ground Beef Other Ground Meat Salm.
|
From page 23... ...
Use of Salmonella Serotype Data for Estimating Attribution Comprehensive Salmonella surveillance -- including characterization of human, food, animal, and environmental isolates with a combination of serotyping and molecular subtyping methods -- is critical for improving our understanding of Salmonella transmission and facilitating, in the long term, science-based approaches to Salmonella attribution. In particular, population and commodity-specific subtype data are required for the development of mathematical models for attribution of Salmonella to either different reservoirs (for example specific animal-host species)
|
From page 24... ...
Subtype-based attribution estimates thus need to be updated regularly to be accurate and useful. Finally, the Danish model used both serotype data and phage-typing data for a subset of serotypes, while the proposed FSIS approaches only use serotype data, thus relying on more limited subtype discrimination, particularly among the common Salmonella serotypes (for example, Typhimurium)
|
From page 25... ...
FSIS has not used some data that are readily available to supplement the CDC outbreak data and expert elicitations. This could help in the development of better-informed attribution estimates.
|
From page 26... ...
In addition, FSIS should articulate the metrics that it will use to demonstrate public-health outcomes; the metrics should be evaluated by using data sources that are independent of those generated by USDA. If FSIS continues to include attribution as a component in its PHRBIS, FSIS in conjunction with CDC staff and others, should review the CDC outbreak database, including information not considered in the initial FSIS attribution model, to improve attribution of illnesses to regulated food products.
|
From page 27... ...
Recognizing that food-attribution data are of interest to many agencies, FSIS should work collaboratively with CDC, FDA, and other federal and state agencies to develop a common set of definitions for microbial foodborne-disease attribution; a coordinated approach to improve the quality and consistency of data used among agencies in determining food-attribution estimates; a process that allows for regular updating of attribution estimates; and a standardized coding scheme for food vehicles, including multi-component foods. FSIS should continue to collaborate with CDC and other appropriate organizations in the serotyping and molecular subtyping of all Salmonella isolates, with emphasis on those obtained from specific food products.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.