Reacting coping and preventing

During the first several decades of the twentieth century, food safety in the industrialized world could be largely categorized as a cycle of reacting and coping -reacting to outbreaks and coping with sporadic illnesses. However, by the latter two decades a much greater emphasis was placed on prevention of all disease, both outbreak-related and sporadic. From the food safety toolbox (Table 8.6), a variety of tools have been used to decrease the morbidity, mortality, and costs of food-borne disease. Current analyses are focusing on the relative effectiveness and impact of each tool.

Sporadic infections account for the vast majority of food-borne illnesses. Of the total burden of food-borne disease in the United States, there is no identified agent in 81 percent of cases (Mead et al., 1999), although many of these may be due to viral causes. While outbreaks may not be a large proportion of the total disease burden of food-borne illness, they are extremely important for the focus they bring to food safety efforts.

Food-borne outbreaks have been important catalysts of regulatory change, such as required time and temperature conditions for precooked roast beef following Salmonella outbreaks (IOM, 2003b), pathogen reduction steps such as pasteurization for apple cider and fresh juices because of associated E. coli O157:H7 (cider) and Salmonella (juice) infections (IOM, 2003b), and new processing requirements for ready-to-eat poultry and meat products after a large

Table 8.6 The food safety toolbox and future needs

Tool

Twenty-first century need

Surveillance

More real-time data analysis

• Syndromal

Enhanced virtual networks for public

health communication

• Pathogen-specific

• Computer analyzed

Greater international participation

"Farm to fork" continuum

Tighter vertical integration

• Conceptual approach

Regulatory framework

Eliminate fragmented statutory foundation

• Inspection

• Microbial sampling

Creation of science-based standards

• Microbial standards

Regulatory flexibility

• Performance standards

HACCP

More extensive use

Education and behavioral change

Improve effectiveness

• Consumers

Broader reach

• Food producers, processors

Traceability

Broader application

Greater depth for traceback

Irradiation

Broader commodity approval

Greater public acceptance

Quantitative microbial risk assessment

Inform food safety objectives

Lawsuits and legal liability

multi-state outbreak of listeriosis due to turkey deli meat (Gottlieb et al, 2006). The large-scale E. coii O157:H7 outbreak in the western United States (Bell et al., 1994) spurred the Pathogen Reduction/Hazard Analysis Critical Control Program regulation by the United States Food Safety Inspection Service (FSIS). HACCP is an engineering control, aiming to prevent contamination rather than inspecting to remove defective product. Originally implemented and validated in processed foods, HACCP was implemented in 1996 for meat and poultry slaughter facilities, and modified HACCP approaches are being used in seafood and food service.

Surveillance has been, and will remain, the cornerstone of the foundation of food safety in particular, and public health in general. At one time, surveillance was pathogen-specific and almost synonymous with postcards, bulging filing cabinets, and dreary reports lacking timeliness and filled with minutiae. Today, surveillance is increasingly electronic, and not just for a specific pathogen but also for a syndrome or illness. Particularly in food-borne disease, surveillance is being used not just to find outbreaks and remove contaminated vehicles from commerce, but also to drive applied research for prevention measures. Molecular subtyping of E. coli O157:H7 over a two-year period in Minnesota showed multiple subtypes, identifying only four outbreaks during the period of the study (Bender et al., 1997). The data were suggestive that there may be multiple "mini-outbreaks," with different sources, moving transiently and quickly through the food supply. The attendant implication is that control measures need to be multifactorial.

"FoodNet" has been a cooperative effort in the United States to conduct population-based studies of sporadic food-borne disease (Allos et al., 2004). It has provided an improved, more precise estimate of actual disease occurrence - for example, that 39 symptomatic cases of Salmonella infection occur for every one case that is cultured and reported (Voetsch et al., 2004). Now in its tenth year, FoodNet has allowed comparison of disease trends over time (CDC, 2006a), and has been used to measure the impact of regulatory changes aimed at prevention of food-borne infection. While Campylobacter, E. coli O157:H7, Listeria, and Salmonella infections have all decreased since 1996, seemingly correlated with the Pathogen Reduction and Hazard Analysis Critical Control Program (HACCP), most of that decrease was in the first four years after its implementation. For E. coli O157:H7 the incidence at FoodNet sites has been the same for the past three years, and may reflect non-food-borne transmission.

For egg-associated Salmonella enteriditis there has been only a partial success in the convergence of measures to control the problem, including on-farm egg quality assurance programs, continuous refrigeration of shell eggs, and education for consumers, restaurants, and retail and institutional kitchens. While the incidence has decreased from a high of 3.9 per 1,000,000 in 1994 (10 in the New England states) to 2.2 per 1,000,000 in 2003, the latter is double the incidence in the 1980s (Braden, 2006).

"PulseNet" is a national network of state public health laboratories in which molecular genetic analysis ("DNA fingerprinting") of food-borne pathogens is digitized and shared via a secured electronic network. By showing which cases have the same subtype, PulseNet has repeatedly speeded recognition of geographically diffuse, low-level outbreaks, as well as separating outbreak from sporadic background cases - in both circumstances providing direction for epidemiologic investigation and source ascertainment. Similar laboratory networks for food-borne pathogens exist in Canada and Europe ("EnterNet"). The challenges in bringing these networks together and adding additional world regions include the use of standardized protocols for molecular analysis and interpretation, transparency in data sharing, and compatibility of the computer networks.

A recent outbreak of salmonellosis illustrates the convergence of several trends to find a notable weak spot in food protection in the United States. Many case-patients were Latino or Asian - a clue that led to the identification that illness was linked to the consumption of imported mangos. This exotic fruit must be disinfested to prevent the importation of the Mediterranean fruit fly. A hot-water dip technique was used, but the water was not chlorinated or filtered; the technique had been mandated by USDA and was widely used, but had not been assessed for microbiological implications (Sivapalasingam et al., 2003). The hot-water dip method was implemented in order to move away from a fumigation method with carcinogenic potential, but it had not been fully evaluated for microbiological effectiveness, thus fulfilling the "law of unintended consequences" (Jones and Schaffner, 2003).

Irradiation of foods (including the aforementioned mangos) could substantially reduce food-borne infections (Tauxe, 2001; Osterholm, 2004; Osterholm and Norgren, 2004). It is supported by a wealth of data on safety, as well as by federal agencies in the United States (CDC, USDA, FDA), a variety of medical and public health organizations, food processing groups, and international organizations (WHO, FAO). Although approved for use in the United States on meat, poultry, fruits, and vegetables, it is used in <0.002 percent of these commodities (US General Accounting Office, 2000). The barriers to its broader use are related to ignorance, lack of consumer acceptance, and subsequent small market share for irradiated product.

Legal liability and lawsuits have had some effect on food companies, although this has been difficult to quantify. Restaurants were the targets of one-third of the lawsuits from 1988 to 1997 (Buzby et al., 2001). Parent companies were the next largest category targeted. Of those that went to court, only 31 percent were won by the plaintiff, with a median award of $25,560 in 1998 dollars. The data are distorted by the fact that many claims are settled out of court, the details are not publicly available, and (probably) the weaker claims go to court. As food tracing systems become deeper and more effective at traceback, the ability to identify the point of contamination improves. This increases the potential for product liability to be assigned to a specific company, and would be a direct legal incentive to produce safer foods.

An outbreak of E. coli O157:H7 infections in the late summer of 2006 is illustrative of the problems with the current tools for food safety when viewed in the context of modern trends in food-borne disease. Nearly 200 cases occurred, spread over more than half of the 50 states and Canada. Infection was acquired by the consumption of a "healthy" food, raw bagged spinach (CDC, 2006b). The spinach was traced under multiple brand names and through distributors to production within three counties in southern California; the ultimate source of the contamination is unknown as this chapter is going to press. This latest outbreak illustrates that problems with food-borne pathogens in produce cannot be lopsidedly assigned only to imported produce. Regulations such as microbial standards would need to be applied equally to imported as well as domestic product, if they are to be effective in reducing disease, and avoid constituting a trade barrier.

A major shortcoming in many food-borne disease outbreaks is that they represent "too much, too late." The outbreak unfolds in the rearview mirror, with retrospective construction of the chain of events that led to contamination and the spread of illness. Recalls of contaminated product not infrequently occur too late to affect the epidemic curve, because the contaminated vehicle quickly cleared through the food distribution system. Chasing the horse after it is out of the barn is a costly consumption of scarce public health resources, and re-emphasizes the primacy of prevention strategies.

What are the needs for the twenty-first century in food safety, and how should the tools in the toolbox (Table 8.6) be used? The populations in the industrialized countries will continue to grow, with more elderly persons, greater ethnic diversity in younger populations, and more people living longer with immuno-compromising conditions (see Figure 8.4). The emphasis will remain on dietary patterns to prevent cardiovascular disease, cancer, osteoporosis, and obesity, with less red meat and saturated fats, and more fresh fruits, vegetables, grains, poultry, and fish. A large proportion of the foods consumed will be imported, prepared outside the home, and/or consumed at restaurants or other commercial food-service locations. Food safety in the industrialized nations will exist in a new equilibrium with the health and environmental conditions in the developing world. New pathogens will be identified and others will re-emerge into new ecological niches.

The regulatory framework in the United States has been a patchwork of statutory regulations developed using science that is now considered outdated, such as the organoleptic basis for meat inspection (IOM, 2003b). A move toward science-based standards that utilize the tools of modern molecular biology coupled with greater regulatory flexibility would keep pace with the shift in population demographics. Tighter vertical integration along the farm-to-fork continuum would foster greater awareness of microbial hazards among food producers, processors, retailers, and consumers, and would be expected to drive markets. Real-time surveillance, already feasible, would need to be coupled with realtime analysis and appropriate action. This is particularly germane to preparedness for a bioterrorist attack through the food supply.

Food safety objectives (FSOs) provide an integration of risk assessment and public health objectives translated into a numerical goal. FSOs work in reverse, from the public health objective (e.g. reducing the incidence of pathogen x-related illness to a specified level or by a specified proportion at a defined time) to a target for food processors (e.g. that no more than y cfu/gram of pathogen x can be present in the serving at the time of consumption). The FSO defines the acceptable level of protection (ALOP), a numerical value left undefined in HACCP (IOM, 2003b). The future of food safety is coming into focus in risk

I I Baby Boom

Male

(Age) 85+ 80-84 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4

85+ 80-84 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4

85+ 80-84 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4

Female

Percentage of total population Percentage of total population

Figure 8.4 United States population age structure 1960-2020. Source: US Bureau of the Census, www.census.gov/ipc/prod/97agewc.pdf.

management economics, an emerging field. When the cost of the intervention(s) is integrated with the benefit(s) to society as a whole, an appropriate level of protection (ALOP) can be calculated (IOM, 2003b). In this approach, as the level of food safety increases, there is greater marginal cost to society (Figure 8.5). It can also be deduced that with tighter control of the food supply for microbial pathogens, additional interventions to "enhance" food safety come with less benefit and greater cost.

Figure 8.5 Toward a public health goal: relating an appropriate level of protection (ALOP) to marginal social benefit and cost. Reproduced with permission of the Institute of Medicine.
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