Scientific Criteria to Ensure Safe Food (2003) / Chapter Skim
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2 The Science of Public Health Surveillance
2 The Science of Public Health Surveillance
Pages 28-68
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From page 28... ...
Outbreak investigations can also identify critical gaps in knowledge, leading to applied research and ultimately to better long-term prevention as unsafe food handling processes are corrected or new food hazards are identified and controlled. The information gathered through surveillance and subsequent investigations of outbreaks and of sporadic cases can reveal the magnitude and trends of foodborne diseases, which helps policy makers target prevention strategies.
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From page 29... ...
Increased concern following the large Escherichia cold 0157:H7 outbreak in 1993 associated with consumption of undercooked ground beef (Bell et al., 1994) stimulated enhancements in surveillance for foodborne infections (FSIS, 1998c)
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From page 30... ...
For example, the network of state public health laboratories detected a multistate cluster of Salmonella Newport infections that had the same pulsed-field gel electrophoresis profile. As a result of the investigation of genetic profiles, 78 infections in 13 states were linked to consumption of imported mangoes (Sivapalasingam et al., 2000~.
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From page 31... ...
The following sections describe how these strategies are utilized in both nationwide and sentinel site surveillance by public health agencies in the United States. Specialized surveys that relate the contribution of consumer behavior to the level of specific foodborne illness risk are described as well.
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From page 32... ...
This website is a new mechanism for the global surveillance of foodborne diseases. Molecular subtyping is now expanding the power of surveillance to detect outbreaks that appear as sporadic cases and is improving the ability of public health authorities to investigate outbreaks by comparing the molecular "fingerprint" of bacterial strains associated with sporadic cases of a foodborne disease.
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From page 33... ...
In some situations, serotyping and subtyping of pathogens, coupled with nationwide surveillance, provide an ideal system to link a cluster of cases. Considering that state and local public health systems provide the only nationwide population-based surveillance for foodborne diseases, and that outbreak investigations are critical to identify new pathogens and new food safety hazards, the committee recommends that foodborne outbreak investigation and reporting by state and local health departments be enhanced.
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From page 34... ...
Foodborne Outbreak Reporting A foodborne outbreak is a cluster of two or more similar infections that are shown by investigation to result from ingestion of the same food (Olsen et al., 2000~. Local and state health departments conduct most foodborne outbreak investigations.
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illness and the likelihood of seeking medical care for a diarrhea! illness; this information was critical to develop a general estimate of the burden of foodborne disease (Herikstad et al., 2002b; Mead et al., 1999~.
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From page 36... ...
In an outbreak setting, where careful comparison of food consumption patterns of a group of ill persons with those of a group who remained well can identify the immediate food vehicle, it is still difficult sometimes to determine which of the various ingredients was the source of the illness. However, many outbreak investigations are definitive, and comparison of patterns observed among groups of outbreaks can help define patterns.
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From page 37... ...
These pathogen-based point estimates can provide a benchmark for assessing the economic impact of foodborne diseases, such as the $6.9 billion estimated cost to society from the diseases caused by the major foodborne bacterial pathogens (Buzby and Roberts, 1996~. Some foodborne infections can also cause chronic complications in a small percentage of cases; for example, kidney failure related to E
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From page 38... ...
The burden of reported foodborne outbreaks can also be measured. National foodborne outbreak reporting from 1998 through 2000 gave a combined annual incidence of 4.8 outbreaks per 1 million persons in the population (FDDB, 2002a)
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From page 39... ...
Trends in Foodborne Disease Standard case surveillance data, such as that collected from the national Salmonella surveillance program, provide nationwide data on the prevalence and trends of specific serotypes of Salmonella. However, unreported cases due to not seeking medical attention or not performing the diagnostic occur.
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From page 40... ...
. Systematic review of the Salmonella surveillance data through 1997 indicates that there have been important declines in several serotypes associated with swine and with poultry, and increases in serotypes associated with reptiles (such as pet turtles and snakes)
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From page 41... ...
, increased attention to fresh produce safety, implementation of HACCP in the seafood industry, application of HACCP to juice processing, and heightened awareness about the importance of food safety controls for imported foods. Changes in slaughter and processing procedures and sanitation are likely to have played an important role in reducing the incidence of four important foodborne diseases between 1996 and 2001.
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From page 42... ...
For example, the number of foodborne outbreaks reported to CDC increased sharply in 1998 from 400 to 500 per year (1990-1993) to 1,300 to TABLE 2.2 Incidence of Selected Foodborne Diseases in FoodNet, 2001, and the Healthy People 2010 Goals Pathogen Incidence, 2001a (per 100,000)
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CDC initiates improved | reporting ,; 1990 1992 1994 1996 1998 2000 2002 Year FIGURE 2.4 Foodborne disease outbreaks reported to the Centers for Disease Control and Prevention, January 1, 1990, through March 15, 2002.
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From page 44... ...
and to foods such as cold salads and sandwiches that are handled extensively in the kitchen (and to direct contamination from ill food handlers) (Kohn et al., 1995; Parashar and TABLE 2.3 Specific Association of Commodity Food Groups and Pathogens Food Group Pathogens Beef Salmonella, Escherichia cold 0157:H7 Poultry Campylobacter, Salmonella Pork Staphylococcus aureus, Yersinia enterocolitica, Salmonella, Toxoplasma, Trichinella Ready-to-eat meats Listeria monocytogenes Dairy L
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From page 45... ...
Data on outbreaks associated with foods, supplemented with data from sporadic cases, provide the most readily available public health information for allocating the burden of specific infections across food groups. For example, between 1993 and 1997, 1,152 foodborne disease outbreaks with a determined food vehicle, which involved 46,453 illnesses, were reported in the United States (updated from Olsen et al., 2000~.
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From page 46... ...
Other food safety surveys were conducted by FDA in 1988, 1993,1998, and 2001 to gather data on consumer food-safety practices related to crosscontamination and consumption of potentially risky foods (Consumer Studies Branch, 2002~. The data showed large improvements consisting of the reduction
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From page 47... ...
Overall, consumer behavior surveys indicate that although some changes in consumer behavior have occurred, consumer habits are still frequently less than optimal. The committee recommends periodic repetition of such surveys to help document behavioral changes concerning food safety in the population at large as a result of consumer education efforts, and to target food safety messages to subgroups of the population that engage in risky food-preparation and consumption behavior.
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From page 48... ...
Because systematic monitoring is a powerful tool for tracking specific microbial hazards, particularly if coupled with molecular subtyping, the committee recommends expansion of this type of monitoring to all high-risk food groups. For meat and poultry, although not designed to be an optimal surveillance system, product sampling as part of PR/HACCP verification provides some information about the frequency of Salmonella in specific meat and poultry products, about the impact of plant size on contamination levels, and about trends in specific serotypes (Rose et al., 2002; RTI, 2002b)
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From page 49... ...
Conducting additional studies on pathogen prevalence in animals arriving at processing plants would be a critical component for progress in foodborne disease prevention. The contamination is not likely to be random.
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From page 50... ...
were positive for Salmonella and an equal percentage were positive for Shigella. Considering the increasing importance of raw produce as a vehicle of foodborne infections in the United States, the committee recommends that high-risk (i.e., known to be frequently associated with foodborne infections)
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From page 51... ...
expand the scope of participation by food safety laboratories in eLEXNET. Association of Human Diseases with Specific Reservoirs Comparing information from monitoring and surveillance in animals, foods, and humans can document and even quantify the flow of specific pathogens from particular reservoirs to humans.
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From page 52... ...
While food safety policy may be guided by monitoring hazard levels in animals or foods, and contaminated food certainly is associated with human illness, the relationships that link contamination levels in foods at processing with incidences of human illness is likely to be more complex than a simple oneto-one linear correspondence. Factors such as multiplication of microorganisms during distribution and preparation undoubtedly affect this relationship.
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From page 53... ...
more complete and accurate. There is a dose-response relationship for many foodborne infections.
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From page 54... ...
Knowledge about food choices, cleanliness, storage, preparation, cooking, and serving practices can help reduce the risk posed to the host by microbial hazards in foods. USE OF PUBLIC HEALTH DATA TO IMPROVE FOOD SAFETY: SPECIFIC EXAMPLES Preventing foodborne disease is complex, requiring attention and intervention from farm or fishery to table (TOM/NRC, 1998~.
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From page 55... ...
Escherichia cold 0157:H7 and Apple Cider In 1992, investigation of an outbreak of E cold 0157:H7 infections in Massachusetts linked this pathogen to apple cider for the first time (Besser et al., 1993~.
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From page 56... ...
In the early l990s, a pilot project to develop flock-based screening and control measures was begun: the Pennsylvania Egg Quality Assurance Program (Schlosser et al., 1999~. This project became the model for other states' egg quality assurance programs.
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From page 57... ...
cold 0157:H7, and Alfalfa Sprouts Like S Enteritidis in eggs, the new food safety problem with alfalfa sprouts is not an emerging pathogen, but rather the emergence of well-known pathogens in a different food.
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From page 58... ...
Later that year, an outbreak in Connecticut was traced to traditional cheese made from insufficiently pasteurized milk from Massachusetts dairy farms (McCarthy et al., 2002~. In 2002, an investigation of a multistate cluster of cases in the Northeast linked the illness to eating ground beef traced to meat from a single slaughter plant (Zansky et al., 2002~.
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From page 59... ...
Riskmanagement policies applied throughout the food system on farms, fisheries, and orchards; in slaughter facilities and processing plants; during transportation and storage; and in retail food stores, food service establishments, and homesare all key parts of food safety. For certain products, it may be possible to define varying levels of processing depending on microbiological and other markers of the risk that they are contaminated.
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From page 60... ...
1994. A multistate outbreak of Escherichia cold 0157:H7 Associated bloody diarrhea and hemolytic uremic syndrome from hamburgers.
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2001. A multistate outbreak of Escherichia cold 0157:H7 infections linked to alfalfa sprouts grown from contaminated seeds.
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Morb Mortal Wkly Rep 51:1149-1152. CFSAN (Center for Food Safety and Applied Nutrition)
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From page 63... ...
Presented at the International Conference on Emerging Infectious Diseases, CDC, Atlanta, GA, July 16-19. FSIS (Food Safety and Inspection Service)
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From page 64... ...
Emerg Infect Dis 8:490-495. Hennessy TW, Hedberg CW, Slutsker L, White KE, Besser-Wiek JM, Moen ME, Feldman J
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From page 65... ...
Emerg Infect Dis 3:395-400. IOM/NRC (Institute of Medicine/National Research Council)
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Emerg Infect Dis 5:607-625.
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From page 67... ...
Emerg Infect Dis 7:382-389.
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From page 68... ...
2001. Food safety and irradiation: Protecting the public health from foodborne infections.
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